Markedly improving lipase-mediated asymmetric ammonolysis of D,L-p-hydroxyphenylglycine methyl e

唾液酸化修饰的英语英文回答：Saliva is a complex fluid that plays a crucial role in maintaining oral health. It contains a variety of proteins, enzymes, and other molecules that help to protect the teeth and gums from damage. One of the most important functions of saliva is to neutralize acids that are produced by bacteria in the mouth. This helps to prevent tooth decay and other oral health problems.In addition to its buffering capacity, saliva also contains a number of antimicrobial substances that help to kill bacteria. These substances include lysozyme, lactoferrin, and immunoglobulins. Lysozyme is an enzymethat breaks down the cell walls of bacteria, while lactoferrin is a protein that binds to iron, which is essential for bacterial growth. Immunoglobulins are antibodies that recognize and bind to specific bacteria, helping to neutralize them.Saliva also plays a role in taste perception. The proteins in saliva bind to taste molecules and carry them to the taste buds on the tongue. This allows us to perceive the different tastes of food and drink.The composition of saliva can vary depending on a number of factors, including age, diet, and health status. For example, the saliva of young children contains more antimicrobial substances than the saliva of adults. This is because young children are more susceptible to oral infections. The saliva of people who eat a healthy diet is also more likely to contain antimicrobial substances than the saliva of people who eat a diet high in sugar and processed foods.Saliva is an essential fluid for oral health. It helps to protect the teeth and gums from damage, kill bacteria, and perceive taste. The composition of saliva can vary depending on a number of factors, but it is always an important part of a healthy mouth.中文回答：唾液是维持口腔健康的重要液体。

mediator蛋白植物特异亚基mediator蛋白是一类在生物体内发挥重要调控作用的蛋白质。

它在植物中具有特异亚基，这也是植物体内调控过程中的重要组成部分。

本文将重点介绍mediator蛋白特异亚基在植物中的功能和作用。

mediator蛋白是一种多亚基复合物，参与了转录调控过程中的多个环节。

它通过与转录因子和RNA聚合酶II相互作用，调控基因的转录过程。

mediator蛋白的特异亚基在植物中有着重要的功能，它们能够与不同的转录因子相互作用，从而调控特定基因的表达。

mediator蛋白特异亚基在植物的生长发育过程中起着重要作用。

例如，在根的生长发育中，mediator蛋白的特异亚基能够与根发育相关的转录因子相互作用，调控根的生长和分化。

此外，在花器官的发育中，mediator蛋白的特异亚基也能够与花发育相关的转录因子相互作用，调控花器官的形成和发育。

mediator蛋白特异亚基在植物的应答逆境胁迫过程中发挥重要作用。

植物在面临逆境胁迫时，需要调节一系列与逆境应答相关的基因的表达。

mediator蛋白的特异亚基可以与逆境应答转录因子相互作用，从而调控逆境应答相关基因的表达。

例如，在干旱胁迫下，mediator蛋白的特异亚基与干旱应答转录因子相互作用，调控干旱应答相关基因的表达，从而增强植物的耐旱能力。

mediator蛋白特异亚基还在植物的激素信号传导中扮演重要角色。

激素是植物生长和发育的重要调节因子，而mediator蛋白的特异亚基能够与激素信号转录因子相互作用，调控激素信号相关基因的表达。

例如，auxin是一种重要的植物生长素，mediator蛋白的特异亚基能够与auxin信号转录因子相互作用，调控auxin信号相关基因的表达，从而调节植物的生长和发育过程。

mediator蛋白的特异亚基在植物的生长发育、逆境应答和激素信号传导等过程中发挥着重要作用。

它们通过与特定转录因子相互作用，调控特定基因的表达，从而影响植物的生理过程。

翻译后修饰方式调控动脉粥样硬化发病机制的研究动脉粥样硬化是一种常见的心血管疾病，其可引发心脑血管事件，影响人们的生活质量以及寿命长度。

目前医学领域对于动脉粥样硬化的研究正在进行，其中最新的一项研究旨在通过翻译后修饰方式调控动脉粥样硬化发病机制，以期开发出更为高效的治疗方法。

翻译后修饰是指由翻译后的蛋白质修饰酶进行的以改变蛋白质结构和功能的修饰作用，包括糖基化、磷酸化、乙酰化等。

这种修饰机制对于疾病的发生、发展和治疗都有着重要的作用，因此，翻译后修饰已成为医学领域研究的热点之一。

动脉粥样硬化的发病过程与一系列炎症反应和氧化应激有关，而这些过程又会受到翻译后修饰的影响。

因此，通过调控翻译后修饰方式，可以有效地改善动脉粥样硬化的发病机制。

糖基化是翻译后修饰方式中最为常见的一个，它与许多疾病的发病有着密切的关联，其中也包括动脉粥样硬化。

糖基化的主要作用是改变蛋白质的物理化学性质和功能，进而影响其与其他生物分子的相互作用和信号转导。

针对动脉粥样硬化，糖基化修饰可以影响血管内皮细胞的正常功能，导致血管内皮细胞增生，细胞附着和纤维蛋白形成增加，从而进一步促进动脉粥样硬化的进程。

因此，在治疗动脉粥样硬化时，抑制糖基化修饰可以是一个有效的策略。

除了糖基化，乙酰化和磷酸化等修饰方式也被广泛研究，并被认为在动脉粥样硬化的发病机制中起着重要作用。

乙酰化修饰可以通过调节蛋白质表达和转录因子活性等多种途径，影响动脉粥样硬化的发病。

而磷酸化修饰则可以通过改变蛋白质的酶活性、结构以及稳定性，对动脉粥样硬化的进展产生积极或消极的作用。

综上所述，翻译后修饰方式调控动脉粥样硬化发病机制的研究已经成为医学领域的热门研究方向。

针对不同的修饰方式，开发针对性的治疗方法可以有效地减缓疾病的进展和发展，提高治疗效果。

未来，随着技术和研究的不断进步，翻译后修饰方式调控的临床应用将会更加广泛和深入。

Inositol lipid regulation of lipid transferin specialized membrane domainsCell 2013 2 9在特异的膜域肌醇脂质调控脂质的转运The highly dynamic membranous network of eukaryotic cells allows spatial organization of biochemical reactions to suit the complex metabolic needs of the cell.真核细胞内高度动态化的膜网络结构提供生物化学反应的空间组织以适应细胞复杂代谢活动的需求.The unique lipid composition of organelle membranes in the face of dynamic membrane activities assumes that lipid gradients are constantly generated and maintained.在面对动态膜活动的脂质梯度的假说中细胞器膜的特异性脂质成分在不断的形成并且维持稳定。

Important advances have been made in identifying specialized membrane compartments and lipid transfer mechanisms that are critical for generating and maintaining lipid gradients.在确定专业膜隔间和脂质转运机制已经取得重要进展,脂质转运是至关重要的对于脂质梯度的产生与维持。

Remarkably, one class of minor phospholipids – the phosphoinositides – is emerging as important regulators of these processes.值得注意的是，一类小的磷脂磷酸肌醇正在被认识,他们是这些过程的重要调节器。

蛋白质翻译后修饰技术及在药物研发中的应用随着生物医学领域的快速发展，越来越多的药物正在被开发和研究。

其中，蛋白质药物占据了越来越大的份额。

而蛋白质的翻译后修饰技术在药物研发中也起着至关重要的作用。

蛋白质翻译后修饰技术是指在蛋白质翻译完成之后，通过特定的酶加工和修饰蛋白质分子。

这些加工和修饰可以改变蛋白质的结构、功能和活性，并且可以增加蛋白质的生物物理稳定性、溶解度和药代动力学特性，从而提高药物的治疗效果和安全性。

目前，常用的蛋白质翻译后修饰技术主要包括：糖基化、磷酸化、乙酰化、甲基化、乙酰化、甲基化、磺酸化、脂肪酰化、硫酸化、羟化等。

糖基化是一种常见的蛋白质修饰方式，主要是指在蛋白质分子上结合糖分子。

糖基化可以改变蛋白质的溶解度、易降解性、稳定性和免疫原性，对蛋白质的功能和生物学活性有重要影响。

目前，已有很多糖基化蛋白质药物被用于临床治疗。

磷酸化是指磷酸酶通过水解ATP，将磷酸基团添加到蛋白质分子上。

磷酸化可以改变蛋白质的生物学功能、转运、相互作用和信号传导，是一种重要的蛋白质修饰方式。

通过磷酸化的蛋白质药物也越来越多应用于临床治疗。

乙酰化是指乙酰转移酶将乙酰基团添加到蛋白质分子上。

乙酰化可以调节蛋白质的结构、功能和活性，对消化、代谢和信号传导等生物学过程有重要影响。

甲基化是指甲基转移酶将甲基基团添加到蛋白质分子上。

甲基化可以改变蛋白质的结构、功能和亲和性，对生物学过程有重要影响。

一些和癌症相关的蛋白质也经常发生甲基化修饰。

在药物研发中，蛋白质翻译后修饰技术非常重要。

通过这些方式对蛋白质分子进行合理的修改，可以提高药物的稳定性、溶解度、口感、经济性和持续时间等药代动力学特征，同时影响药物的吸收和分布，从而提高药物的疗效和安全性。

目前，各类蛋白质药物在临床中的应用越来越普遍。

在药物对抗肿瘤、心血管疾病、免疫反应等重大疾病的研发中，蛋白质翻译后修饰技术应用的越来越广泛。

通过这些技术的应用，药物可以更加精准地定向作用于疾病相关的蛋白质分子，从而提高疗效、减少副作用。

〈61〉MICROBIAL LIMIT TESTS微生物的限定测试This chapter provides tests for the estimation of the number of viable aerobic microorganisms present and for freedom from designated microbial species in pharmaceutical articles of all kinds, from raw materials to the finished forms. An automated method may be substituted for the tests presented here, provided it has been properly validated as giving equivalent or better results. In preparing for and in applying the tests, observe aseptic precautions in handling the specimens. Unless otherwise directed, where the procedure specifies simply ―incubate,‖hold the container in air that is thermostatically controlled at a temperature between 30and 35,for a period of 24to 48hours.The term ―growth‖ is used in a special sense herein, i. e. ,to designate the presence and presumed proliferation of viable microorganisms.这个篇章提供了目前的可行需氧的微生物的预计数量和不受影响的状态，从所有制药条款里指定的微生物类型，从原材料到毛坯。

[转载]【转】蛋⽩质翻译后修饰棕榈酰化位点预测⼯具 —— CS原⽂地址：【转】蛋⽩质翻译后修饰棕榈酰化位点预测⼯具 —— CS作者：michaelAs a special class of post-translational modifications (PTMs), numerous proteins could be covalently modified by a variety of lipids, including myristate (C14), palmitate (C16), farnesyl (C15), geranylgeranyl (C20) and glycosylphosphatidylinositol (GPI), etc (Casey, 1995 ; Nadolski and Linder, 2007 ; Resh, 2006 ). Although most of lipid modifications are irreversible, protein S-palmitoylation , also called as thioacylation or S-acylation, could reversibly attach 16-carbon saturated fatty acids to specific cysteine residues in protein substrates through thioester linkages (Bijlmakers and Marsh, 2003 ; Dietrich and Ungermann, 2004 ; el-Husseini Ael and Bredt, 2002 ; Greaves and Chamberlain, 2007 ; Linder and Deschenes, 2007 ; Nadolski and Linder, 2007 ; Resh, 2006 ; Resh, 2006 ; Roth, et al., 2006 ; Smotrys and Linder, 2004 ; Wan, et al., 2007 ). Palmitoylation will enhance the surface hydrophobicity and membrane affinity of protein substrates, and play important roles in modulating proteins' trafficking (Draper, et al., 2007 ; Linder and Deschenes, 2007 ), stability (Linder and Deschenes, 2007 ), and sorting (Greaves and Chamberlain, 2007 ), etc. Also, protein palmitoylation has been involved in numerous cellular processes, including signaling (Casey, 1995 ; Kurayoshi, et al., 2007 ; Resh, 2006 ), apoptosis (Chakrabandhu, et al., 2007 ; Feig, et al., 2007 ), and neuronal transmission (Roth, et al., 2006 ; Stowers and Isacoff, 2007 ), etc. Although many efforts have been made in this field, the molecular mechanism underlying protein palmitoylation still remain to be inexplicit.In this work, we updated our previous CSS-Palm 1.0 (Zhou, et al., 2006 ) into version 2.0 . We manually collected the experimentally verified palmitoylation sites from scientific literature. The non-redundant training data contained 263 palmitoylation sites from 109 distinct proteins. Then an improved version of CSS algorithm was deployed. The leave-one-out validation and 4-, 6-, 8-, 10-fold cross-validations were calculated to uate the prediction performance and system robustness of CSS-Palm 2.0 . Again, the prediction performance was also tested on an additional data set not included in the training data set, with 53 palmitoylation sites in 26 proteins. By comparison with our previous CSS-Palm1.0 and NBA-Palm 1.0 (Xue, et al., 2006 ; Zhou, et al., 2006 ), the performance of CSS-Palm 2.0 was greatly improved. Finally, the CSS-Palm 2.0 was implemented in JAVA 1.4.2 with high speed . The CSS-Palm 2.0 could predict out potential palmitoylation sites for ~1,000 proteins (with an average length of ~1000aa) within five minutes. Taken together, we proposed that the CSS-Palm 2.0 will be a great help for experimentalists. The CSS-Palm 2.0 is freely available at: .本⽂来⾃CSDN博客：/casularm/archive/2008/07/22/2688098.aspx。

DOI 10.1378/chest.08-06722008;133;199S-233S ChestCarlo Patrono, Colin Baigent, Jack Hirsh and Gerald Roth*Antiplatelet Drugsull.html /content/133/6_suppl/199S.f and services can be found online on the World Wide Web at: The online version of this article, along with updated informationISSN:0012-3692)/site/misc/reprints.xhtml (of the copyright holder.may be reproduced or distributed without the prior written permission Northbrook, IL 60062. All rights reserved. No part of this article or PDF by the American College of Chest Physicians, 3300 Dundee Road, 2008Physicians. It has been published monthly since 1935. Copyright CHEST is the official journal of the American College of ChestAntiplatelet Drugs*American College of Chest PhysiciansEvidence-Based Clinical Practice Guidelines(8th Edition)Carlo Patrono,MD;Colin Baigent,MD;Jack Hirsh,MD,FCCP;and Gerald Roth,MDThis article about currently available antiplatelet drugs is part of the Antithrombotic and Thrombo-lytic Therapy:American College of Chest Physicians Evidence-Based Clinical Practice Guidelines (8th Edition).It describes the mechanism of action,pharmacokinetics,and pharmacodynamics of aspirin,reversible cyclooxygenase inhibitors,thienopyridines,and integrin␣IIb␤3receptor antago-nists.The relationships among dose,efficacy,and safety are thoroughly discussed,with a mechanistic overview of randomized clinical trials.The article does not provide specific management recommen-dations;however,it does highlight important practical aspects related to antiplatelet therapy, including the optimal dose of aspirin,the variable balance of benefits and hazards in different clinical settings,and the issue of interindividual variability in response to antiplatelet drugs.(CHEST2008;133:199S–233S)Key words:abciximab;antiplatelet drugs;aspirin;clopidogrel;dipyridamole;eptifibatide;platelet pharmacology;resistance; ticlopidine;tirofibanAbbreviations:ACEϭangiotensin-converting enzyme;ADPϭadenosine diphosphate;AMPϭadenosine monophos-phate;ATTϭAntithrombotic Trialists;CAPRIEϭClopidogrel vs Aspirin in Patients at Risk of Ischemic Events; CHDϭcoronary heart disease;CIϭconfidence interval;COMMITϭClopidogrel and Metoprolol Myocardial Infarction Trial;COXϭcyclooxygenase;CUREϭClopidogrel in Unstable Angina to Prevent Recurrent Events;EPICϭEvaluation of 7E3for the Prevention of Ischemic Complications;ESPSϭEuropean Stroke Prevention Study;ESPRITϭEuropean Stroke Prevention Reversible Ischemia Trial;FDAϭFood and Drug Administration;GPϭglycoprotein;INRϭinternational normalized ratio;MIϭmyocardial infarction;NSAIDϭnonsteroidal antiinflammatory drug;ORϭodds ratio; PCIϭpercutaneous coronary intervention;PEϭpulmonary embolism;PGϭprostaglandin;PTCAϭpercutaneous trans-luminal coronary angioplasty;RRϭrate ratio;TIAϭtransient ischemic attack;TXϭthromboxane;TTPϭthrombotic thrombocytopenic purpuraP latelets are vital components of normal hemosta-sis and key participants in atherothrombosis by virtue of their capacity to adhere to injured blood vessels and to accumulate at sites of injury.1Al-though platelet adhesion and activation can be viewed as a physiologic repair response to the sud-den fissuring or rupture of an atherosclerotic plaque, uncontrolled progression of such a process through a series of self-sustaining amplification loops can lead to intraluminal thrombus formation,vascular occlu-sion,and transient ischemia or infarction.Currently available antiplatelet drugs interfere with some steps in the activation process,including adhesion,release, and/or aggregation,1and have a measurable impact on the risk of arterial thrombosis that cannot be dissociated from an increased risk of bleeding.2In discussing antiplatelet drugs,it is important to appreciate that approximately1011platelets are pro-duced each day under physiologic circumstances,a level of production that can increase up to10-fold at*From the Catholic University School of Medicine(Dr.Patrono), Rome,Italy;Clinical Trial Service Unit(Dr.Baigent),University of Oxford,Oxford,UK;Hamilton Civic Hospitals(Dr.Hirsh), Henderson Research Centre,Hamilton,ON,Canada;and Seattle VA Medical Center(Dr.Roth),Seattle,WA.Dr.Patrono was supported in part by a grant from the European Commission FP6(LSHM-CT-2004-005033).Manauscript accepted December20,2007.Reproduction of this article is prohibited without written permission from the American College of Chest Physicians(www.chestjournal. org/misc/reprints.shtml).Correspondence to:Carlo Patrono,MD,Catholic University School of Medicine,Largo F.Vito1,00168Rome,Italy;e-mail: carlo.patrono@rm.unicatt.itDOI:10.1378/chest.08-0672SupplementANTITHROMBOTIC AND THROMBOLYTIC THERAPY8TH ED:ACCP GUIDELINES CHEST/133/6/JUNE,2008SUPPLEMENT199Stimes of increased need.3Platelets are anucleate blood cells that form by fragmentation of megakaryo-cyte cytoplasm and have a maximum circulating life span of about10days in humans.3Platelets provide a circulating source of chemokines,cytokines,and growth factors,which are preformed and packaged in storage granules.Moreover,activated platelets can synthesize prostanoids(primarily,thromboxane[TX] A2)from arachidonic acid released from membrane phospholipids through rapid coordinated activation of phospholipase(s),cyclooxygenase(COX)-1and TX synthase(Fig1).Newly formed platelets also express the inducible isoforms of COX(COX-2)and prosta-glandin(PG)E synthase,and this phenomenon is markedly amplified in association with accelerated platelet regeneration.4Although activated platelets are not thought to synthesize proteins de novo,they can translate constitutive messenger RNAs into pro-teins,including interleukin-1␤,over several hours.5 Thus,platelets may play previously unrecognized roles in inflammation and vascular injury,and anti-platelet strategies may be expected to affect platelet-derived protein signals for inflammatory and/or pro-liferative responses.1Negative modulation of platelet adhesion and aggre-gation is exerted by a variety of physiologic mecha-nisms,including endothelium-derived prostacyclin (PGI2),nitric oxide,CD39/ecto-ADPase,and platelet endothelial cell adhesion molecule-1.Some drugs may interfere with these regulatory pathways,as exempli-fied by the dose-dependent inhibition of PGI2produc-tion by aspirin and other COX inhibitors.22.0Aspirin and Other COX Inhibitors Aspirin has been thoroughly evaluated as an anti-platelet drug6and was found to prevent vascular death by approximately15%and nonfatal vascular events by about30%in a metaanalysis ofϾ100 randomized trials in high-risk patients.72.1Mechanism of Action of AspirinThe best characterized mechanism of action of the drug is related to its capacity to inactivate permanently the COX activity of prostaglandin H-synthase-1and-2 (also referred to as COX-1and COX-2).8–12These isozymes catalyze the first committed step in prosta-noid biosynthesis(ie,the conversion of arachidonic acid to PGH2)[Fig1].PGH2is the immediate precursor of PGD2,PGE2,PGF2␣,PGI2,and TXA2. COX-1and COX-2are homodimers of aϳ72kd monomeric unit.Each dimer has three independent folding units:an epidermal growth factor-like do-main;a membrane-binding domain;and anenzy-Figure1.Arachidonic acid metabolism and mechanism of action of aspirin.Arachidonic acid,a20-carbon fatty acid containing four double bonds,is liberated from the sn2position in membranephospholipids by several forms of phospholipase,which are activated by diverse stimuli.Arachidonicacid is converted by cytosolic PGH synthases,which have both COX and hydroperoxidase activity,tothe unstable intermediate PGH2.The synthases are colloquially termed COXs and exist in two forms,COX-1and COX-2.Low-dose aspirin selectively inhibits COX-1,and high-dose aspirin inhibits bothCOX-1and COX-2.PGH2is converted by tissue-specific isomerases to multiple prostanoids.Thesebioactive lipids activate specific cell membrane receptors of the superfamily of G-protein-coupledreceptors.DPϭPGD2receptor;EPϭPGE2receptor;FPϭPGF2␣receptor;IPϭprostacyclinreceptor;TPϭTX receptor.200S Antithrombotic and Thrombolytic Therapy8th Ed:ACCP Guidelinesmatic domain.12Within the enzymatic domain,there is the peroxidase catalytic site and a separate,but adjacent site for COX activity at the apex of a narrow, hydrophobic channel.The molecular mechanism of permanent inactiva-tion of COX activity by aspirin is related to blockade of the COX channel as a consequence of acetylation of a strategically located serine residue(Ser529in the human COX-1,Ser516in the human COX-2) that prevents access of the substrate to the catalytic site of the enzyme.13The hydrophobic environment of the COX channel stabilizes the modified serine side-chain against hydrolysis.13Thus,inhibition of COX-1–dependent platelet function can be achieved with low doses of aspirin given once daily.In con-trast,inhibition of COX-2–dependent pathophysio-logic processes(eg,hyperalgesia and inflammation) requires larger doses of aspirin(probably because acetylation is determined by the oxidative state of the enzyme and is inhibited in cells with high peroxide tone)14and a much shorter dosing interval(because nucleated cells rapidly resynthesize the enzyme).Thus, there is an approximately100-fold variation in daily doses of aspirin when used as an antiinflammatory rather than as an antiplatelet agent.Furthermore, the benefit/risk profile of the drug depends on the dose and indication because its GI toxicity is dose dependent(see below).Human platelets and vascular endothelial cells process PGH2to produce primarily TXA2and PGI2, respectively.11TXA2induces platelet aggregation and vasoconstriction,whereas PGI2inhibits platelet aggregation and induces vasodilation.11Whereas TXA2is largely a COX-1–derived product(mostly from platelets)and thus highly sensitive to aspirin inhibition,vascular PGI2can derive both from COX-1and,to a greater extent even under physio-logic conditions,from COX-2.16COX-1–dependent PGI2production occurs transiently in response to agonist stimulation(eg,bradykinin)15and is sensitive to aspirin inhibition.COX-2–mediated PGI2produc-tion occurs long term in response to laminar shear stress17and is largely insensitive to aspirin inhibition at conventional antiplatelet doses.This may explain the substantial residual COX-2–dependent PGI2 biosynthesis in vivo at daily doses of aspirin in the range of30to100mg,18despite transient suppres-sion of COX-1–dependent PGI2release.15It is not established that more profound suppression of PGI2 formation by higher doses of aspirin is sufficient to initiate or predispose to thrombosis.However,two lines of evidence suggest that PGI2is thrombopro-tective.The first is the observation that mice lacking the PGI2receptor had increased susceptibility to experimental thrombosis.19The second is the obser-vation of the cardiovascular toxicity associated with COX-2inhibitors20that also supports the concept of PGI2acting as an important mechanism of throm-boresistance in the setting of inadequate inhibition of platelet TXA2biosynthesis.212.2PharmacokineticsAspirin is rapidly absorbed in the stomach and upper intestine.Peak plasma levels occur30to40 min after aspirin ingestion,and inhibition of plate-let function is evident by1h.In contrast,it can take up to3to4h to reach peak plasma levels after administration of enteric-coated aspirin.If only enteric-coated tablets are available,and a rapid effect is required,the tablets should be chewed.The oral bioavailability of regular aspirin tablets is ap-proximately40to50%over a wide range of doses.22 A considerably lower bioavailability has been re-ported for enteric-coated tablets and sustained-release,microencapsulated preparations.22Lower bioavailability of some enteric-coated preparations and poor absorption from the higher pH environ-ment of the small intestine may result in inadequate platelet inhibition,particularly in heavier subjects.23 Both a controlled-release formulation15and a trans-dermal patch24with negligible systemic bioavailabil-ity have been developed in an attempt to achieve selective inhibition of platelet TXA2production with-out suppressing systemic PGI2synthesis.The former was used successfully in the Thrombosis Prevention Trial(see below),but it remains unknown whether there is any advantage to the controlled-release formulation vis-a`-vis plain aspirin.The plasma concentration of aspirin decays with a half-life of15to20min.Despite the rapid clearance of aspirin from the circulation,the platelet-inhibitory effect lasts for the life span of the platelet25because aspirin irreversibly inactivates platelet COX-1.8,9As-pirin also acetylates the enzyme in megakaryocytes before new platelets are released into the circula-tion.10,26–28The mean life span of human platelets is approximately8to10days.Therefore,about10to 12%of circulating platelets are replaced every 24h.29,30However,the recovery of TXA2biosynthe-sis in vivo following prolonged aspirin administration is somewhat faster than predicted by the rate of platelet turnover,18possibly because of the nonlinear relationship between inhibition of platelet COX-1 activity and inhibition of TXA2biosynthesis in vivo31 (Fig2).2.3Issues Concerning the Antithrombotic Effects of AspirinA number of issues related to the clinical efficacy of aspirin continue to be debated.These include the following:(1)the optimal dose of aspirin in order to CHEST/133/6/JUNE,2008SUPPLEMENT201Smaximize efficacy and minimize toxicity;(2)the suggestion that part of the antithrombotic effect of aspirin is unrelated to inhibition of platelet TXA 2;and (3)the possibility that some patients may be aspirin “resistant.”2.3.1The Optimal Dose of Aspirin:Well-designed,placebo-controlled randomized trials have shown that aspirin is an effective antithrombotic agent when used long term in doses ranging from 50to 100mg/d,and there is a suggestion that it is effective in doses as low as 30mg/d.6,7Aspirin,75mg/d,was shown to be effective in reducing the risk of acute myocardial infarction (MI)or death in patients with unstable angina 32and chronic stable angina,33as well as in reducing stroke or death in patients with transient cerebral ischemia 34and the risk of postoperative stroke after carotid endarterectomy.35In the Euro-pean Stroke Prevention Study (ESPS)-2,aspirin 25mg bid was effective in reducing the risks of stroke and of the composite outcome stroke or death in patients with prior stroke or transient ischemic attack (TIA).36Moreover,in the European Collaboration on Low-Dose Aspirin in Polycythemia vera Trial,37aspirin,100mg/d,was effective in preventing throm-botic complications in patients with polycythemia vera,despite a higher-than-normal platelet count.The lowest effective dose of aspirin for these various indications is shown in Table 1.The clinical effects of different doses of aspirin have been compared directly in a relatively small number of randomized trials.38–43In the United Kingdom TIA study,41no difference in efficacy was found between 300and 1,200mg/d of aspirin (see below).In a study of 3,131patients after a TIA or minor ischemic stroke,aspirin in a dose of 30mg/d was compared with a dose of 283mg/d,and theExtra Platelet SourcesPlatelet SynthesisTXA 2TXB 22,3-dinor-TXB 2& other metabolitesUrineTXB 2Production In VivoEnzymesLiver H 2OCalculated Rate of TXB 2Production In Vivo : 0.1 ng/kg/minP e r c e n t a g e I n h i b i t i o n o f U r i n a r y 2,3-d i n o r -T X B 2E x c r e t i o n I n V i v oPercentage Inhibition of SerumTXB 2Ex VivoPharmacologic InhibitionEx Vivo vs In VivoTXB 2Production Ex Vivo10020030003060 minS e r u m T X B 2n g /m lTimeWhole Blood Clotting at 37°CMaximal Biosynthetic Capacity 300-400 ng/ml in 1 hrFigure 2.Maximal capacity of human platelets to synthesize TXB 2,rate of TXB 2production in healthy subjects,and relationship between the inhibition of platelet COX activity and TXB 2biosynthesis in vivo .Left panel:The level of TXB 2production stimulated by endogenous thrombin during whole-blood clotting at 37°C.62Center panel:The metabolic fate of TXA 2in vivo and the calculated rate of its production in healthy subjects on the basis of TXB 2infusions and measurement of its major urinary metabolite.Right panel:The nonlinear relationship between inhibition of serum TXB 2measured ex vivo and the reduction in the excretion of TX metabolite measured in vivo .31Table 1—Vascular Disorders for Which Aspirin Has Been Shown To Be Effective and Lowest Effective Dose(Section 2.3.1)DisorderLowest Effective Daily Dose,mgTIA and ischemic stroke *50Men at high cardiovascular risk 75Hypertension 75Stable angina 75Unstable angina *75Severe carotid artery stenosis *75Polycythemia vera 100Acute MI160Acute ischemic stroke *160*Higher doses have been tested in other trials and were not found to confer any greater risk reduction.202SAntithrombotic and Thrombolytic Therapy 8th Ed:ACCP Guidelineshazard ratio for the group receiving the lower dose was0.91(95%confidence interval[CI],0.76to 1.09).42The Acetylsalicylic Acid and Carotid Endar-terectomy Trial reported that the risk of stroke,MI, or death within3months of carotid endarterectomy is significantly lower for patients taking81or325 mg/d aspirin than for those taking650or1,300mg (6.2%vs8.4%;pϭ0.03).43Thus,there is no con-vincing evidence from randomized studies that have compared different doses of aspirin that higher doses are more effective in reducing the risk of serious vascular events.In fact,both this limited set of randomized comparisons and the indirect compari-sons reported in the overview of the Antithrombotic Trialists’(ATT)Collaboration(Table2)are compat-ible with the reverse(ie,blunting of the antithrom-botic effect at higher doses of aspirin,consistent with dose-dependent inhibition of PGI2).Such inhibition of PGI2may be a potential mechanism by which COX-2inhibitors produce an excess risk of MI(see below).The antithrombotic effects of a range of doses of aspirin also have been compared with an untreated control group in a number of thrombotic vascular disorders.The doses have varied between50and 1,500mg/d.Aspirin has been shown to be effective in the following conditions:unstable angina in which the incidence of acute MI or death was significantly reduced in four separate studies using daily doses of 75mg,32325mg,44650mg,45and1,300mg46;stable angina in which a dose of75mg/d reduced the incidence of acute MI or sudden death33;aortocoro-nary bypass surgery in which the incidence of early occlusion was similarly reduced with daily doses of 100mg,47325mg,48975mg,49and1,200mg49; thromboprophylaxis of patients with prosthetic heart valves who also received warfarin in whom the incidence of systemic embolism was reduced with daily doses of100mg,50500mg,51and1,500mg52,53; thromboprophylaxis of patients with arterial venous shunts undergoing long-term hemodialysis in whom a dose of160mg/d was shown to be effective54;acute MI in which a dose of162.5mg/d reduced early (35-day)mortality as well as nonfatal reinfarction and stroke55;transient cerebral ischemia in which doses between50and1,200mg/d were effective34,36,41,56–58; acute ischemic stroke in which doses of160to300 mg/d were effective in reducing early mortality and stroke recurrence59,60;and polycythemia vera in which100mg,37but not900mg,61was effective in reducing fatal and nonfatal vascular events. Thus,aspirin is an effective antithrombotic agent in doses between50and1,500mg/d.It is also possible from the results of the Dutch TIA study that 30mg/d is effective.42There is no evidence that low doses(50to100mg/d)are less effective than high doses(650to1,500mg/d)and,in fact,the opposite may be true.These clinical findings are consistent with saturability of platelet COX-1inactivation at doses as low as30mg/d.62There is evidence,however,that doses of approx-imately300mg/d produce fewer GI side effects than doses of approximately1,200mg/d.41There is also some evidence that a dose of30mg/d produces fewer side effects than300mg/d.42The Clopidogrel in Unstable Angina To Prevent Recurrent Events (CURE)investigators have retrospectively investi-gated the relationship between the aspirin dose(the CURE protocol recommended75to325mg/d)and risk of major bleeding.63This study was a random-ized comparison of clopidogrel with placebo on a “background”of aspirin therapy.Patients with acute coronary syndromes receiving aspirin,Յ100mg/d, had the lowest rate of major or life-threatening bleeding complications both in the placebo(1.9%) and in the clopidogrel(3%)arms of the trial.Bleed-ing risks increased with increasing aspirin dose with or without clopidogrel.63In summary,the saturability of the antiplatelet effect of aspirin at low doses,the lack of dose-response relationship in clinical studies evaluating its antithrombotic effects,and the dose dependence of its side effects all support the use of as low a dose of aspirin as has been found to be effective in the treatment of various thromboembolic disorders(Ta-ble1).Use of the lowest effective dose of aspirin(50 to100mg/d for long-term treatment)is currently the most appropriate strategy to maximize its efficacy and minimize its toxicity.62.3.2Effects of Aspirin Not Related to TXA2: Aspirin has been reported to have effects on hemostasis that are unrelated to its ability to inactivate platelet COX-1.These include dose-dependent inhibition of platelet function,64–68enhancement of fibrinolysis,69–71 and suppression of plasma coagulation.72–75In contrast to the saturable and well-characterized (nanomolar aspirin concentration,rapid time course, physiologic conditions,single serine modification)Table2—Indirect Comparison of Aspirin Doses Reducing Vascular Events in High-RiskPatients(Section2.3.1)*Aspirin Dose,mg/d No.ofTrialsNo.ofPatientsOddsReduction500–1,5003422,45119Ϯ3%160–3251926,51326Ϯ3%75–150126,77632Ϯ6%Ͻ7533,65513Ϯ8%*Data are from Lindemann et al5/2001. CHEST/133/6/JUNE,2008SUPPLEMENT203Sinhibition of COX-1by aspirin,13,62,76the putative mechanisms underpinning the non-PG effects of aspirin on hemostasis are dose dependent and less clearly defined.For example,inhibition of shear-induced platelet aggregation depends on the level of aspirin provided,and enhanced fibrinolysis due to N-acetylation of lysyl residues of fibrinogen is seen in vivo with high doses of aspirin(650mg bid)69and proceeds more rapidly in vitro under nonphysiologic alkaline conditions.77Aspirin suppresses plasma co-agulation through several mechanisms.The first, initially described in1943by Link et al and con-firmed by others,72,73is caused by an antivitamin K effect of aspirin.It requires very high doses of aspirin and does not contribute to the antithrombotic effect of aspirin when the drug is used in doses up to1,500 mg/d.The second is platelet dependent and is characterized by inhibition of thrombin generation in a whole blood system.74,75A single dose of500mg depresses the rate of thrombin generation,whereas repeated daily dosing with300mg of aspirin reduces the total amount of thrombin formed.78An interac-tion with platelet phospholipids,which is blunted in hypercholesterolemia,has been proposed to explain the effects of aspirin on thrombin generation.78It is possible(but unproven)that this effect occurs as a consequence of impaired platelet coagulant activity secondary to inhibition of TX-dependent platelet aggregation.It is unknown whether lower doses of aspirin are able to produce this effect.This sort of in vitro effect has been shown for other platelet inhibi-tors,such as glycoprotein(GP)-IIb/IIIa antagonists(see below).Furthermore,high-dose aspirin can cause ab-normal coagulation in vitro by direct acetylation of one or more clotting factors.This can be demonstrated in platelet-poor plasma and,thus,is not related to platelet inhibition or vitamin K antagonism.Additional studies in both animal models and human subjects have reported antithrombotic effects of aspirin that may occur,at least in part,through mechanisms unrelated to inactivation of platelet COX-1.In animal models,Buchanan et al66and Hanson et al64reported that optimal antithrombotic activity of aspirin required doses in excess of those required to inhibit TXA2.In clinical studies,the results of a subgroup analysis of the North American Symptomatic Carotid Endarterectomy Trial study79 suggested that aspirin in doses ofՆ650mg/d might be more effective thanՅ325mg/d for the preven-tion of perioperative stroke in patients having carotid artery surgery.80This retrospective observation was refuted by a second prospective study,the Acetylsal-icylic Acid and Carotid Endarterectomy Trial,43 which tested the hypothesis that the wide area of collagen exposed by endarterectomy is a sufficiently strong stimulus to platelet aggregation to require a larger dose of aspirin.Approximately3,000patients scheduled for carotid endarterectomy were ran-domly assigned81,325,650,or1,300mg/d aspirin, started before surgery and continued for3months. The combined rate of stroke,MI,or death at3 months was significantly(pϭ0.03)lower in the low-dose groups(6.2%)than in the high-dose groups (8.4%)[primary analysis].There were no significant differences between the81-mg and325-mg groups or between the650-mg and1,300-mg groups in any of the secondary analyses of the data.43A subgroup analysis of the Physicians’Health Study,81based on post hoc measurements of baseline plasma C-reactive protein performed in543appar-ently healthy men who subsequently had MI,stroke, or venous thrombosis,and in543study participants who did not report vascular complications,has found that the reduction in the risk of a first MI associ-ated with the use of aspirin(325mg on alternate days)appears to be directly related to the level of C-reactive protein,raising the possibility of antiin-flammatory as well as antiplatelet effects of the drug in cardiovascular prophylaxis.82This hypothesis is unlikely to be correct because,as noted above,the antiinflammatory effects of aspirin and other nonste-roidal antiinflammatory drugs(NSAIDs)are largely related to their capacity to inhibit COX-2activity induced in response to inflammatory cytokines,12as these clinical effects can be fully reproduced by highly selective COX-2inhibitors(coxibs)in patients with rheumatoid arthritis.83As shown in Table3,the dose and time dependence of the effects of aspirin on nucleated inflammatory cells expressing COX-2 vs anucleated platelets expressing COX-1are mark-edly different,thus making a clinically relevant anti-inflammatory effect of the drug at325mg everyTable3—Dose and Time Dependence of the Effects of Aspirin on Platelets and Inflammatory Cells(Section2.3.2)Cellular Target EnzymeSingleDose,*mgDuration of ProstanoidSuppression,hCumulative Effects UponRepeated DosingDailyDose,†mgPlatelets COX-110024–48Yes50–81 Inflammatory cells COX-2Ն6503–4No3,000–5,000 *Dose causing full suppression of prostanoid formation and/or clinically detectable functional effect after single dosing.†Range of doses shown clinically effective in long-term trials of cardiovascular protection or rheumatoid arthritis.204S Antithrombotic and Thrombolytic Therapy8th Ed:ACCP Guidelinesother day pharmacologically implausible.Finally, aspirin has been reported to modify the way in which neutrophils and platelets84or erythrocytes and plate-lets85,86interact,to protect endothelial cells from oxidative stress,87and to improve endothelial dys-function in atherosclerotic patients.88However,nei-ther the molecular mechanism(s)nor the dose de-pendence of these effects have been clearly established.Although improved endothelial dysfunc-tion could reflect an antiinflammatory effect of aspirin of relevance to atherogenesis,it should be emphasized that the hypothesis has never been tested by an appropriately sized controlled prospec-tive study.All of the evidence detailed above suggesting dose-dependent effects for aspirin is indirect and inconsistent with the failure to show a dose effect in randomized clinical trials and in the ATT overview analysis.7This failure to show a dose effect is the critical point of the discussion because it correlates with the saturability of the aspirin effect on platelet COX-1.For example,in studies with purified en-zyme and with isolated platelets,nanomolar concen-trations of aspirin will completely block PG synthesis within20min after exposure.89Higher concentra-tions and longer exposures will not alter the inhibi-tory effect of aspirin on PG synthesis because of this saturable quality.Exactly the same feature(maximal effect at low doses,absence of dose effect)is seen in clinical trials with aspirin as an antithrombotic agent. When one raises the dose of aspirin in this situation, no further or additional effect can be appreciated because the critical event has already taken place, namely,maximal inhibition of platelet TX synthesis. Thus,the consistency of dose requirements and saturability of the effects of aspirin in acetylating the platelet enzyme,8inhibiting TXA2production,25,62 and preventing atherothrombotic complications6,7 constitutes the best evidence that aspirin prevents thrombosis through inhibition of TXA2production. It is likely,therefore,that any of the potential effects of aspirin on other determinants of arterial throm-bosis are much less important than the inhibition of platelet COX-1activity.2.3.3Aspirin“Resistance”:The term aspirin resis-tance has been used to describe a number of differ-ent phenomena,including the inability of aspirin to (1)protect individuals from thrombotic complica-tions,(2)cause a prolongation of the bleeding time, (3)reduce TXA2production,or(4)produce a typical effect on one or more in vitro tests of platelet function.90From a therapeutic standpoint,it is im-portant to establish whether aspirin resistance can be overcome by increasing the dose of aspirin,but unfortunately very few data bear directly on this issue.The fact that some patients may experience recurrent vascular events despite long-term aspirin therapy should be properly labeled as treatment failure rather than aspirin resistance.Treatment failure is a common phenomenon occurring with all drugs(eg,lipid-lowering or antihypertensive drugs). Given the multifactorial nature of atherothrombosis and the possibility that platelet-mediated thrombosis may not be responsible for all vascular events,it is not surprising that only a fraction(usually one fourth to one third)of all vascular complications can be prevented by any single preventive strategy.It has been reported that a variable proportion(up to one fourth)of patients with cerebrovascular dis-ease only achieve partial inhibition of platelet aggre-gation at initial testing,and some(up to one third) seem to develop resistance to aspirin over time,even with increasing doses.91–93The results of these long-term studies carried out by Helgason et al are at variance with those of a short-term study of Weksler et al,94showing that aspirin,40mg/d,inhibited platelet aggregation and TXA2formation as effec-tively as higher doses of aspirin in patients who had recent cerebral ischemia.Variable platelet responses to aspirin have also been described in patients with peripheral arterial disease95and with ischemic heart disease.96–98In the Buchanan and Brister study,96 aspirin nonresponders were identified on the basis of bleeding time measurements.Approximately40%of patients undergoing elective coronary artery bypass grafting showed no prolongation of bleeding time in response to aspirin.This finding was associated with increased platelet adhesion and12-HETE synthe-sis.96In contrast,repeated measurements of platelet aggregation performed over24months of placebo-controlled treatment by Berglund and Wallentin99 demonstrated that100patients with unstable coro-nary artery disease randomized to receive aspirin, 75mg/d,in the Research Group on Instability in Coronary Artery Disease in Southeast Sweden study32had consistently reduced platelet aggregation without attenuation during long-term treatment. Based on measurements of platelet aggregation in response to arachidonate and adenosine diphosphate (ADP),5%and24%of patients with stable cardio-vascular disease who were receiving aspirin(325 mg/d forՆ7days)were defined as resistant and semiresponders,respectively.97Using a variety of techniques,including conventional aggregometry, shear stress-induced activation,and the expression of platelet surface receptors,Sane et al98recently re-ported that57%of a group of88patients with documented heart failure who had been treated with aspirin,325mg/d,forՆ1month showed aspirin nonresponsiveness.Overall,the majority of these studies were characterized by the following major CHEST/133/6/JUNE,2008SUPPLEMENT205S。

分子生物学习题答案第一章绪论Chapter 1 Introduction一名词解释1．人类基因组计划：与曼哈顿原子弹计划和阿波罗登月计划相媲美的美国人类基因组计划（human genome project, HGP)，解读人基因组上的所有基因、24个染色体DNA分子中的碱基序列。

在―人类基因组计划‖中，分为两个阶段：DNA序列图以前的计划和DNA序列图计划。

序列图前计划包括遗传图、物理图、转录图。

2. RFLP (restrict fragment length polymorphism )：A variation from one individual to the next in the number of cutting sites for a given restriction endonuclease in a given genetic locus.3. DNA指纹：基因组中存在着多种重复序列，拷贝数从几个到数十万个，可分为串联重复序列和分散重复序列。

根据个体重复序列拷贝的位置和数目的差异，使用限制性内切酶，获得具有个体特异性的DNA片段。

可以作为亲缘关系或个人身份的鉴定。

4. SNP（single nucleotide polymorphism, 单核苷酸多态性）：在一个群体中，基因组内某一特定核苷酸位置上出现2种或2种以上不同核苷酸的现象，在群体中相应频率为1-2%。

如果低于这个频率，可视为点突变。

二简答1. What is molecular biology？Molecular biology is the subject of gene structure and function at the molecular level.To explain the principle of development, metabolism, heredity and variation, aging at the molecular level. It grew out of the disciplines of genetics and biochemistry.2. Major events in the genetics century第二章核酸、蛋白质结构一选择题：B, E, D, A, A二名词解释1．Transfection：describes the introduction of foreign material into eukaryotic cells using a virus vector or other means of transfer. The term transfection for non-viral methods is most often used in reference to mammalian cells, while the term transformation is preferred to describe non-viral DNA transfer in bacteria and non-animal eukaryotic cells such as fungi, algae and plants.2．Configuration：The configuration of a molecule is the permanent geometry that results from the spatial arrangement of its bonds. The ability of the same set of atoms to form two or more molecules with different configurations is stereoisomerism.Configuration is distinct from chemical conformation, a shape attainable by bond rotations.3．构象：(Conformation, generally means structural arrangement），指一个分子中不改变共价键结构，仅是单键周围的原子旋转所产生的原子空间排列。

International Journal of Pharmaceutics 395 (2010) 44–52Contents lists available at ScienceDirectInternational Journal ofPharmaceuticsj o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /i j p h a rmReviewSite-specific drug delivery systems within the gastro-intestinal tract:From the mouth to the colonJoão F.Pinto ∗Faculdade de Farmácia,Universidade de Lisboa,Av.Prof.Gama Pinto,P-1640-003Lisboa,Portugala r t i c l e i n f o Article history:Received 30April 2010Accepted 4May 2010Available online 28 May 2010Keywords:ColonOesophagusOral drug delivery MouthSmall intestine Stomacha b s t r a c tDelivery of drugs by the oral route remains the most spread route to administer medicines to patients.The manuscript takes into consideration the most important organs of the digestive system (mouth,oesophagus,stomach,small intestine and colon),their size,physiology and transit patterns of dosage forms while travelling in the digestive tract.For each organ several strategies are considered,namely,adhesion,chemical modification of drug and/or excipient moieties,technological features of dosage forms (e.g.porosity,disintegration time),pH variations or transit times.The manuscript considers strategies that are commonly used in practice for long-term administration of drugs,without interfering with human physiology,and feasible industrially.© 2010 Elsevier B.V. All rights reserved.Contents 1.Introduction..........................................................................................................................................452.Delivery to the mouth................................................................................................................................452.1.Sublingual administration....................................................................................................................452.2.Fast disintegration and effervescency........................................................................................................452.3.Chewing dosage forms .......................................................................................................................452.4.Effect of adhesion.............................................................................................................................452.5.Alternative dosage forms.....................................................................................................................463.Oesophagus ..........................................................................................................................................474.Stomach..............................................................................................................................................474.1.Floating systems due to density..............................................................................................................474.2.Floating systems due to gas generation......................................................................................................474.3.Systems acting by swelling...................................................................................................................484.4.Effect of adhesion.............................................................................................................................484.5.Alternative devices...........................................................................................................................495.Small intestine .......................................................................................................................................495.1.Effect of pH ...................................................................................................................................495.2.Effect of adhesion.............................................................................................................................495.3.Other systems ................................................................................................................................496.Colon .................................................................................................................................................496.1.Chemical modification .......................................................................................................................506.2.Polymer degradation.........................................................................................................................506.3.pH-dependent systems.......................................................................................................................506.4.Time-dependent release......................................................................................................................506.5.Effect of adhesion.............................................................................................................................516.6.Other systems ................................................................................................................................517.Conclusions ..........................................................................................................................................51References ...........................................................................................................................................51∗Tel.:+351217946434;fax:+351217946434.E-mail address:jfpinto@ff.ul.pt .0378-5173/$–see front matter © 2010 Elsevier B.V. All rights reserved.doi:10.1016/j.ijpharm.2010.05.003J.F.Pinto/International Journal of Pharmaceutics395 (2010) 44–52451.IntroductionThe oral route remains the most considered one for administra-tion of drugs.Several reasons can be pointed out to support this fact, namely ease of administration and full control of administration by the patient,together with a high degree offlexibility on dos-ing.However,due to differences on physiology,preferential site of drug absorption,dosage forms must be tailored to a specific organ or even a part of the organ.Site controlled release is usually con-trolled by environmental factors,like the pH or enzymes present in the lumen,whereas the drug release from time controlled sys-tems is controlled primarily by the delivery system and ideally not by the environment(Bussemer et al.,2001).Knowledge of transit times allows the use of time controlled release systems to deliver a drug to a specific location in the digestive system.In fact,the use of particular polymers or mixtures of polymers mayfine tune the release of a drug within the gastro intestinal tract(e.g.targeting to the colon)(Siepmann et al.,2008).The systems discussed in this review are more complex than conventional dosage forms requir-ing special care on production to accomplish their function.The strategies discussed are the ones that can be used on chronic dis-eases encompassing different materials,dosage forms,geometries and technologies.Other systems used in research,clinical trials or under the supervision of a health care professional are discussed superficially.2.Delivery to the mouth2.1.Sublingual administrationThe sublingual route of administration has been considered for many years for acute situations,namely for the administration of nitro-glycerine,avoidingfirst pass metabolism and fast entry into the systemic circulation(Goswami et al.,2008).The same principle has been suggested for the administration of salbutamol sulphate in a fast dissolvingfilm in an acute attack of asthma.Thefilm was prepared by a solvent evaporation technique containing polyvinyl alcohol,glycerol and mannitol(Mashru et al.,2005).Other tech-niques include freeze-drying of materials and/or inclusion of high fractions of superdisintegrants.When the solubility of a drug is a problem(e.g.cannabidiol)inclosing complexes with cyclodextrins may minimize it(Mannila et al.,2007).The complexes can then be transformed into dosage forms(e.g.films,tablets).2.2.Fast disintegration and effervescencyIn recent years,the fast release of drugs in the mouth has attracted attention due to the advantages of such systems,namely, ease of administration and quick effect onset.Many patients(par-ticularly paediatric and geriatric patients)find it difficult to swallow tablets and hard gelatine capsules and do not take their medi-cation as prescribed(Seager,1998).Fast dissolving drug delivery systems either dissolve or disintegrate in the mouth rapidly,with-out requiring any water to aid in swallowing.Processing techniques such as lyophilisation,tablet moulding,sublimation of formulation components,have been considered.Different formulations include sugar-based ingredients,foaming agents and disintegrants(Liang and Chen,2001;Segale et al.,2007).Combination of technologies has been suggested by Baldi and Malfertheiner(2003)by designing enteric coated microgranules compressed to produce a rapidly dispersing tablet:upon adminis-tration,the tablet disintegrates quickly releasing the enteric coated lansoprazole microgranules which were swallowed and dissolved in the small intestine.In a similar approach Giunchedi et al.(2002) proposed the production of tablets containing chlorhexidine diac-etate in chitosan microspheres prepared by spray-drying.Tablets were prepared by direct compression of the microparticles with mannitol alone or with sodium alginate.The release of the drug was controlled by the microspheres polymer.Chitosan diacetate has also been used in the preparation of mono or double layeredfilms with alginate,hydroxypropyl methylcellu-lose by casting and solvent evaporation.Thefilms were soft,flexible and easily handled,allowing an easy application in the buccal cavity (Juliano et al.,2008).Orodispersible tablets containing tramadol have shown improved performance than conventional capsules.Tablets placed into the mouth disintegrate rapidly in contact with the saliva and then swallowed to the stomach and intestine where tramadol was absorbed.Due to the fact this orally dispersible formulation can be taken without liquids,it facilitates an early treatment of emergent pain,irrespective of the place or situation where it may arise(Tagarro et al.,2004).Effervescency has been considered for the production of dosage forms for the ually effervescence is produced in a glass containing water,and the resulting solution is given to patient. However,some suggestions have been made on designing an effer-vescent tablet to stay in the mouth.For instance,fentanyl has been administered as a buccal tablet(Messina et al.,2008),but it has been claimed that its absorption increases when fentanyl was delivered to patients in effervescent tablets,due to an enhanced penetration effect as a consequence of the presence of the gas on the buccal mucosa(Blick and Wagstaff,2006).2.3.Chewing dosage formsChewing gums have been used for many years,particularly in USA,since the release of the drug by chewing the dosage form is an interesting application of gums.Chewing gums based on solid paraffin,lycasin,sorbitol,menthol and peppermint have been described to the administration of antimycotics(miconazole and econazole)for topical application.The solubility problem of these drugs was minimized by the formation of inclusion complexes with cyclodextrins(Jacobsen et al.,1999).A different proposal consid-ers a tablet with three layers comprising a gum core combined with two protective antiadherent external layers,which prevent the adhesion of the gum to the punches of the tabletting machine. In these systems,soluble drugs are freely and easily released from the chewing gums while for actives with reduced water solubility the release rate depends on the chewing time(Fig.1a and b)(Maggi et al.,2005).2.4.Effect of adhesionAdhesion of dosage forms to the buccal mucosa is an attractive strategy to deliver drugs to the buccal cavity.Multiple examples can be found in the literature whereby Carbopol and some cellulose derivatives play a major role on adhesion.Buccal adhesivefilms containing lidocaine and its hydrochlo-ride salt have been prepared with Carbopol971P and glycerol (as a plasticizer)as a controlled release dosage form(Abu-Huwaij et al.,2007);Carbopol934in combination with sodium car-boxy methylcellulose,hydroxypropyl cellulose and hydroxypropyl methylcellulose served as bioadhesive material to deliver ketorolac tromethamine to the mouth:thefilms were produced by casting the materials from aqueous or organic solvents(Ali et al.,1998; Alanazi et al.,2007).Patches with sumatriptan succinate using chitosan were prepared by the solvent casting method.Gelatine and polyvinyl pyrrolidone were incorporated into the patches to improve theirfilm properties(Li et al.,1998;Shidhaye et al.,2008).A bilayered buccal bioadhesivefilm with nicotine hydrogen tar-trate for smoking cessation therapy has been proposed:thefilm comprises a bioadhesive drug layer(hydroxypropyl methylcellu-46J.F.Pinto/International Journal of Pharmaceutics395 (2010) 44–52Fig.1.Release profiles from the residual gums after different chewing times for (a)ranitidine and(b)ketoprofen(average value±S.D.,n=6)(Maggi et al.,2005) (reproduced with permission from the publisher).lose and polycarbophil)and a backing layer which releases the drug at a pre-determined rate for a period of4h(Garg and Kumar,2007);a mucoadhesive buccalfilm of valdecoxib for the treatment of oral submucousfibrosis was made of chitosan and hydroxypropyl methylcellulose(Averineni et al.,2009).Mucoadhesive patches releasing drugs in the oral cavity at a slow pre-determined rate may present advantages over mouth-washes,oral gels and lozenges.For instance,patches prepared by compressing appropriate mixtures containing drug salts com-plexes,lactose,gums(e.g.pectin)were tested in vitro(Burgalassi et al.,1996;Chun et al.,2003);a bioadhesive polymer patch formu-lation with polyisobutylene,polyisoprene and Carbopol934P was prepared using a2-roll milling method for the controlled release of buprenorphine(Guo,1994).The effects of the patches backing materials(ethyl cellulose,polyvinyl pyrrolidone,cellulose acetate, poly(ethylene-co-vinyl acetate))on their hydration and adhesion affecting the control of the drug’s release were investigated(Guo and Cooklock,1996).The production of adhesive gels has also been considered.Piroxi-can in a gel had its absorption increased(by decreasing order)when formulated with hydroxypropyl methylcellulose,hydroxypropyl cellulose,sodium alginate,methyl cellulose,hydroxyethyl cellu-lose,Carbopol934,sodium carboxymethyl cellulose and polyvinyl alcohol,as observed in clinical studies conducted in patients with post-operative dental pain and oedema,following maxillofacial operations(Attia et al.,2004).The hydration rate of the gels has also been addressed particularly in the presence of small water con-tents,as the ones observed in the mouth.Hydrogels of propranolol hydrochloride in Carbopol showed a high adhesion and elasticity to the mucosa even with small amounts of water(Blancofuente et al.,1996).Gel formulations containing5-fluorouracil for the treat-ment of oropharyngeal cancer were prepared by using Poloxamer 407,hydroxypropyl methylcellulose and(poly(methylvinyl)ether-co-maleic anhydride(Gantrez)to form gels(Dhiman et al.,2008).Tablets,as the most popular dosage form,have also been considered.Tabletting of hydroxypropyl methylcellulose with car-bomer can form a complex with buccoadhesive controlled release properties for morphine sulphate(Anlar et al.,1994);the pro-duction of a composite material made of starch and Carbopol 974P by spray-drying has enabled the bioadhesion of micona-zole nitrate tablets to the buccal mucosa(Ameye et al.,2005); multilayer tablets were produced to deliver acitretin:one layer contained Carbopol934P and methyl cellulose with bioadhe-sive properties whereas the other layer contained a slow release matrix(hydroxypropyl methylcellulose)with acitretin(Minghetti et al.,1998).Tablet for buccal delivery of the poor soluble drug carvedilol based on poly(ethyleneoxide)as bioadhesive sustained release platform and hydroxypropyl-p-cyclodextrin as modulator of drug release(Cappello et al.,2006);Carbopol934, together with poly(methylvinylether-co-maleic anhydride)cal-cium or sodium salts(Gantrez),sodium carboxymethylcellulose and poly(ethyleneglycol)8000were used to deliver locally sodium fluoride to the oral cavity for the prevention of caries(Owens et al.,2005).The treatment of periodontal diseases benefits from the preparation of tablets to deliver metronidazole in a matrix containing Carbopol940in mixtures with hydroxyethyl cellu-lose(Perioli et al.,2004).Double layered tablets of benzocaine as regional anaesthetic for dental procedures and in the treat-ment of oral mucositis pain were developed for buccal delivery (Maffei et al.,2004).Buccoadhesive erodible tablets for local deliv-ery of clotrimazole to the oral cavity were produced with different bioadhesive polymers along with soluble excipients like mannitol and poly(ethyleneglycol)6000(Khanna et al.,1996).It should be pointed out that processing conditions do affect the performance of these dosage forms:the bioadhesive characteristics of thermally modified starch with polyacrylic acid tablets containing micona-zole nitrate were affected by the ratio of drum-dried waxy maize starch and polyacrylic acid(Bouckaert and Remon,1993).Hot-melt extrusion technology(HME)was used to prepare mucoadhesive matrixfilms containing clotrimazole for local drug delivery applications for the oral cavity.Thefilm formulation contained hydroxypropyl cellulose and poly(ethyleneoxide)as polymeric carriers,the bioadhesive polycarbophil,and other excip-ients(Repka et al.,2003).Thiocolchicoside in two dosage forms,a bioadhesive disc and a fast dissolving disc for buccal and sublingual administration,has been given to volunteers.The fast dissolving(sublingual)form resulted in a quick uptake of0.5mg of thiocolchicoside within 15min whereas with the adhesive buccal form the same dose can be absorbed over an extended period of time(Artusi et al.,2003).Other less conventional materials have also been used for buccal adhesion.For instance,the gum from Hakea gibbosa(L.)was con-sidered to control the release of calcitonin(Alur et al.,1999;Alur et al.,2001),beads made of either pectins or lectins were comparable to Carbopol934P beads(Bies et al.,2004;Atyabi et al.,2007).2.5.Alternative dosage formsProsthetic devices incorporating drugs are rarely used.The devices available mainly focus on the prophylaxis and the release of antibacterial agents in the mouth.Recently,as buccal delivery sys-tems,they gained some popularity for systemic drug delivery,and prolonged well-controlled release has been identified as beneficial, especially for chronic diseases.Highly miniaturized computerized delivery systems,integrated into a dental appliance can be used for the local treatment of diseases affecting the oral cavity(e.g.peri-odontitis or fungal infections)or for systemic drug delivery(ScholzJ.F.Pinto/International Journal of Pharmaceutics395 (2010) 44–5247et al.,2008).As an example,Jothi et al.(2009)suggested the use of a prosthetic device in the form of a biodegradable chip of chitosan to deliver chlorhexidine for the treatment of periodontitis).3.OesophagusThe oesophagus can be regarded as a connecting organ between the mouth and the stomach,thus it is not designed to hold any dosage form.In fact,the low permeability and transient nature of the oesophagus means that it is unsuitable for the delivery of drugs for systemic action.However,oesophageal disorders includ-ing infections,cancers,motility dysfunction and damage due to gastric reflux may be treated using locally acting agents that offer benefits or reduced dosage and decreased side effects(Batchelor, 2005).On the other hand,on designing dosage forms one should take into consideration the fact that they might be retained in the oesophagus,particularly by relaxation of the organ forming pockets in the lower portion or by reflux from the stomach.The key limitation to the effective drug delivery to the oesopha-gus is sufficient retention at this location.It follows that a suitable formulation either releases the drug in a ready-to-work form at the site of action during the rapid transit through this organ or is retained at the mucosa,releasing the drug throughout time.Differ-ent approaches for targeting the oesophagus have been suggested, encompassing bioadhesive liquids and orally retained lozenges, chewing gums,gels,andfilms,as well as endoscopically deliv-ered drugs(Zhang et al.,2008).Bioadhesion has been achieved with particles coated with an alginate layer(Batchelor et al.,2004). This strategy has been emphasized by combining bioadhesive poly-mers(e.g.a mixture of hydroxypropyl cellulose/Carbopol934)with ultrafine ferrite(Fe2O3)to deliver bleomycin,an anticancer drug. Preliminary studies in rabbits have shown a high holding effect under magnetic guidance at early stages of administration.How-ever,after removal of the magneticfield granules were not retained any more due to non-sufficient bioadhesion provided by the bioad-hesive polymers(Nagano et al.,1997).Although promising,retention of dosage forms in the oesoph-agus can only be fully achieved by a medical device.For instance, photodynamic therapy can be successful to treat various malignan-cies including oesophageal cancer,which is very much dependent on the concentration of photosensitizing drug,light energy deliv-ered to tissue,and the presence of oxygen in the targeted tissue.To achieve this,centring balloons improve light delivery to the oesophageal mucosa,but the pressure of the balloon on oesophageal mucosa could possibly reduce mucosal bloodflow and oxygenation,therefore reducing the effect of photodynamic ther-apy.A balance between the size and the pressure of the balloon is critical to reach the maximum therapeutic effect in oesophageal mucosal dysplasia or cancer in humans(Overholt et al.,1996).4.StomachThe delivery of drugs to the stomach takes advantage of several features of this organ,particularly the ones related to its physiology like the low pH,motility or gastric emptying time.By affecting the physiology,formulation variables including concomitant adminis-tration of other materials,such as food,one can retain a dosage form in the stomach or improve its displacement to the duodenum.In order to retain dosage forms in the stomach and,for that purpose different strategies can be suggested:changes on the density of the dosage forms(e.g.high porosity,swelling or expansion,super porous hydrogels)after administration,bioadhesion and changes on geometry of dosage forms(Hwang et al.,1998;Gangadharappa et al.,2007).Floating,magnetic retention or geometry changes of the dosage form can be achieved with the aim of increasing the bioavailability of the carrying drug by prolonging the gastric resi-dence time.4.1.Floating systems due to densityBuoyancy of a tablet can be achieved by entrapment of air in an agar gel network:thefloating tablet delivered theophylline in a controlled release fashion.The tablet presented a density of0.67 but the retention in the stomach was further emphasized by the presence of food which significantly increased the retention time and overshadowed the effect of density(Desai and Bolton,1993). Similarly,diltiazem tablets have shown a higher hypotensive action when given to patients in afloating controlled release tablet(Gu et al.,1992).Singlefloating controlled drug delivery systems units have been made of polypropylene foam powder,matrix forming polymer,drug andfiller.The resulting highly porous system has shown a low density enablingfloating for8h.Polymers considered in the study were hydroxypropyl methylcellulose,polyacrylates, sodium alginate,corn starch,carrageenan,guar and arabic gums. Although all systems have shown a decrease on density,the drug was released according to different mechanisms(Streubel et al., 2003).In line with this strategy,superporous hydrogels have been synthesized(Chen et al.,2000).These hydrogels swell significantly (volume increases by two orders of magnitude)and fastly in few minutes due to water uptake by capillary wetting through inter-connecting pores.The hydrogels were produced by cross-linking polymerization of various vinyl monomers,or acrylate derivatives in the presence of gas bubbles(Chen et al.,1999;Chen and Park, 2000).Pellets have also been produced asfloating dosage forms and given to patients in hard gelatine capsules.Pharmacokinetic stud-ies were carried out with verapamil(40mg)and the parameters considered(e.g.C max,t max,AUC0–∞,t1/2)were more favourable to pellets than to reference tablets.In vitro test has shown that pellets were able tofloat for6h(Sawicki,2002).Microcapsules containing theophylline and sodium carboxy methylcellulose have been pre-pared by an emulsion phase separation method with chitosan as the matrix forming polymer.Sodium carboxy methylcellulose fraction in the microcapsules played an important role on controlling the floating property of the microcapsules(Lin and Lin,1992).Zou et al.(2008)suggestedfloating systems for chronopharma-cotherapy:afloating pulsatile system was designed to increase the gastric residence time of the dosage form having a lag phase fol-lowed by a burst release of the drug:a core tablet containing the active ingredient was coated with a hydrophilic erodible polymer (responsible for a lag phase in the onset of pulsatile release)and a top buoyant cover layer(methyl cellulose,Carbopol934P and sodium bicarbonate)which controlled thefloating time.Both phar-macokinetic and scintigraphic data pointed out the ability of the system on prolonging residence times of the tablets in the stomach and releasing drugs after a programmed lag-time.4.2.Floating systems due to gas generationThe use of a gas to decrease the density of the dosage form is an alternative to the previous strategy.Floating of dosage forms can be achieved by the inclusion of a gas generator agent in an inert matrix(Baumgartner et al.,2000). Sustained release verapamil hydrochloride has been delivered to patients asfloating tablets produced from granules contain-ing mixtures of a forming matrix(hydroxypropyl methylcellulose, hydroxypropyl cellulose,ethyl cellulose or Carbopol)together with sodium bicarbonate and anhydrous citric acid(Elkheshen et al., 2004).Multi-unit tablets containing furosemide have been formulated and processed as follows:a core containing a solid dispersion of furosemide in polyvinyl pyrrolidone with other excipients pre-pared by direct compression;the core is thenfirst coated with an effervescent layer(mainly sodium bicarbonate)and a second coat with polymethacrylates(Eudragit RL30D,the most promis-48J.F.Pinto/International Journal of Pharmaceutics395 (2010) 44–52Fig.2.Effect of the hydroxypropyl methyl cellulose and effervescent agent content on(A)the drug release(6.4%,w:w,coating level)and(B)the time toflotation of one-layer tablets(coating,Eudragit®RL:ATBC20%,w:w,coating level of6.4or13.0%, w:w)(Krogel and Bodmeier,1999)(reproduced with permission from the publisher).ing).The time tofloat decreased as the amount of the effervescent agent increased and the coating level of the polymer decreased.The minitablets remained in the stomach for about6h,as observed in radiograms(Meka et al.,2009).Krogel and Bodmeier(1999)have designed afloating system with pulsatile drug delivery.In this example a core with the drug contained the effervescent material.The core was coated with a polymeric material either acrylic(Eudragit R,RS,RL or NE)or cel-lulosic(cellulose acetate,ethyl cellulose)polymers.The authors found that a coat with high elongation value and high water and low CO2permeabilities was preferred(e.g.Eudragit RL with acetyl-tributyl citrate)for the effervescent reaction(floating process), whereas,for the pulsatile drug delivery component,a weak semi-permeablefilm which ruptured after a lag-time was the best(ethyl cellulose with dibutylsebacate).The drug was released from the first component by addition of cellulose acetate or hydroxypropyl methylcellulose.Floatation time could be controlled by the com-position(type of polymer and plasticizer)or processing(thickness of the coating or hardness of the core)(Fig.2a and b).A more complex preparation was suggested by Kawashima et al.(1992). These authors suggested the preparation of hollow microspheres loaded with drug(ibuprofen)in their outer polymer shells.The microspheres were prepared by a novel emulsion solvent diffusion method,whereby the ethanol–dichloromethane solution of a drug and an enteric acrylic polymer were poured into an agitated aque-ous solution of polyvinyl alcohol at40◦C.The gaseous phase in the dispersed polymer droplet was generated by the evaporation of the dichloromethane forming an internal cavity in the microsphere of the polymer with the drug.The microballoonsfloated continuously over the surface of acidic dissolution median with surfactant.4.3.Systems acting by swellingThe swelling ability of some materials has been advantageous for the design of dosage forms to deliver drugs to the stomach.By swelling some dosage forms have their density decreased promot-ingfloatation in water.A gastric controlled release drug retention system made of a matrix tablet coated with a permeable membrane,when immersed in simulated gastricfluid expands for18–20h,allowing the release of the drug(e.g.chlopheniramine maleate or riboflavin phosphate). The coat was made of an elastic polymer(Eudragit R)whereas Car-bopol acted as a strong binder to the swollen tablet,mainly due to cross-linked polyvinyl pyrrolidone.In this example the addition of carbonates provided an alkaline microenvironment(optimal pH) enabling the jellification of Carbopol providing buoyancy to the tablet(Deshpande et al.,1997).Expandable gastroretentive dosage forms have their size increased by swelling,prolonging their gastric retention times.After drug release,their dimensions are reduced with evacuation from the stomach.Gastric retention is enhanced by the combination of a substantial increase on the dimensions with a high rigidity of the dosage form to withstand the peristal-sis and mechanical contractility of the stomach(Klausner et al., 2003).Gazzaniga et al.(2008)referred that swellable polymers undergo typical chain relaxation phenomena that coincide with a glassy rubbery transition.In the rubbery phase these polymers may be subject to swelling,dissolution and erosion or,alternatively form an enduring gel barrier when cross-linked networks(hydro-gels)are built.Other materials have been considered.For instance, collagen can expand in the stomach after contact with the gastric fluids formingfloating collagen sponges.These sponges can be pro-duced by freeze-drying a solution of collagen containing a drug(e.g. riboflavin,captopril,acyclovir).The dried product was mixed with hydroxypropyl methylcellulose(Groning et al.,2006)and,once in the stomach,collagen hydrated and swelled.Tablets containing hydroxypropyl cellulose,hydroxyethyl cellu-lose or hydroxypropyl methylcellulose have shown in gastricfluid an outer hydrated layer with a viscoelastic gel structure.This gel was able to entrap air increasing the matrix volume,thus decreas-ing the density(Baumgartner et al.,1998).A different work by Chueh et al.(1995)combined the effect offloating with adhe-sion in a device designed to prolong the residence time of a tablet containing sotalol hydrochloride in the stomach.These effects were achieved by incorporating sodium carboxymethylcellulose, hydroxypropyl methylcellulose,ethyl cellulose and cross-linked polyvinyl pyrrolidone.4.4.Effect of adhesionMucoadhesion of dosage forms to the gastric mucosa has been considered to retain them in the stomach.For instance,mucoad-hesion of microspheres containing acyclovir has been prepared with chitosan,thiolated chitosan,Carbopol and methyl cellulose as mucoadhesive polymers(Dhaliwal et al.,2008).The microspheres containing acyclovir were prepared by an emulsion and a chemical cross-linking technique and then placed into a hard gelatine cap-sule.These capsules upon dissolution released the microspheres as multiunits,which in turn,released the drug in the stomach over a period of12h.Another option encompassed the produc-tion of a patch(3mm in diameter)containing three layers:a water insoluble backing,a model drug(fluorescein,fluorescein isothiocyanate)carrying adhesive layer(dextrane and gel forming polymer)and a pH sensitive enteric polymer(Fig.3)(Eaimtrakarn et al.,2003).A more complex system has been proposed by Lele and Hoffman(2000)based on formulations containing H-bonded complexes of poly(acrylic acid)or poly(methacrylic acid)with poly(ethylene glycol)–drug(indomethacin)conjugates:the com-plexes were designed to dissociate as the formulation swelled in contact with the mucosal surfaces at pH7.4,releasing the PEG-indomethacin conjugate which hydrolysed to release free indomethacin and free polyethylene glycol.Monitoring the orally ingested gastric retentive dosage forms under physiologic conditions has been considered.For instance,。

百泰派克生物科技
质谱分析蛋白质修饰
蛋白质修饰即蛋白质翻译后修饰（Post-Translational Modifications，PTMs），是指蛋白质翻译中或翻译后在蛋白质相关氨基酸残基添加化学基团（如磷酸酯、泛素分子、糖基、酰胺基或甲基等）的过程。

常见的蛋白质翻译后修饰包括磷酸化、糖基化、乙酰化、甲基化和泛素化等。

蛋白质翻译后修饰能赋予蛋白质组丰富的生物学功能，参与调节各项生命活动，如转录调控、细胞生长分化、蛋白转运以及胞间信号传导等。

质谱分析蛋白质修饰就是利用质谱技术对翻译后修饰蛋白质进行鉴定，经翻译后修饰的蛋白质由于添加了相关的化学基团，与没有发生修饰的蛋白相比其分子质量会发生相应的增加，质谱技术就是以此为依据对蛋白质修饰进行分析鉴定的。

质谱技术直接对肽段离子进行检测，从而确定其分子质量，如果待检测的肽段离子带有某种修饰基团，那么其分子质量就会相应的增加该修饰基团的相对分子质量，对于已知序列和分子质量的肽段或蛋白质来说，可以通过计算这种分子质量之差来确定修饰基团的类型，从而进行翻译后修饰鉴定。

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maximal elicitor-mediated activation中文-回复什么是最大激发介导的激活（Maximal Elicitor-Mediated Activation）？最大激发介导的激活是一种特殊的细胞反应，它在许多生物学领域中被广泛研究和应用。

该过程涉及到特定的信号分子（称为最大激发剂）与细胞相互作用，从而引发一系列细胞内和细胞外的生化反应，最终导致某些细胞功能的最大程度激活。

最大激发介导的激活在植物学、免疫学和神经科学等领域中得到了广泛应用，并且已经取得了一些令人印象深刻的研究成果。

最大激发介导的激活过程涉及到多个细胞内和细胞外的信号传导通路。

首先，最大激发剂与特定的受体结合，这些受体通常位于细胞膜上。

受体激活会触发一系列的蛋白质修饰，如磷酸化、脱glycosylation和选择性裂解等，从而引发细胞内信号传导级联反应。

这些反应可以改变细胞内的钙离子浓度、激活一些特定的蛋白质激酶和激酶级联反应，并最终导致激活细胞的特定功能。

此外，最大激发介导的激活还可以通过细胞外的信号分子介导，如激活特定的酶类、细胞因子的释放等。

最大激发介导的激活在不同的实验条件下可以引起不同的细胞功能。

例如，在植物学中，最大激发介导的激活可导致植物的免疫系统被激活，以对抗外部病原体的入侵。

当植物受到病原体感染时，它会释放出最大激发剂，激活细胞免疫反应。

这些反应包括激活植物抗菌肽的合成、激活防御蛋白的表达以及导致病原体细胞破裂等。

类似地，在免疫学中，最大激发介导的激活可激活免疫细胞，如巨噬细胞和淋巴细胞，以对抗病原体的侵袭。

最后，在神经科学中，最大激发介导的激活可以调节神经元之间的突触连接和信息传递。

这些功能的最大激发剂可能是神经递质或其他神经调节物质。

在最大激发介导的激活中，一些重要的研究工具已经被开发出来。

其中之一是探测最大激发剂与细胞受体结合的技术。

这些技术可以帮助我们了解最大激发剂的作用机制，并通过调整最大激发介导的激活来控制特定的细胞功能。

蛋白质翻译后修饰及乙酰化修饰研究在细胞内，蛋白质翻译是一个复杂的过程，包括翻译前、翻译中和翻译后的一系列生化反应。

其中，翻译后修饰是细胞中最为重要的一部分，它能够调节蛋白质的结构和功能，进而影响到细胞内的许多生理过程。

本文将着重讲解蛋白质翻译后修饰中的乙酰化修饰，并介绍一些相关的研究进展。

1. 蛋白质翻译后修饰蛋白质翻译后修饰是指蛋白质分子在翻译完成后，通过各种生化反应进行的一系列化学修饰。

这些修饰能够调节蛋白质的生物学功能和相关信号传导通路。

常见的蛋白质翻译后修饰包括磷酸化、甲基化、乙酰化、泛素化等。

其中，乙酰化修饰在细胞内是一种广泛存在的修饰形式，具有广泛的生物学功能。

2. 乙酰化修饰的生物学功能乙酰化修饰是指在蛋白质分子的赖氨酸残基上结合乙酰化基团，形成N-乙酰赖氨酸残基的一种化学修饰。

这种修饰主要通过组蛋白乙酰转移酶（HATs）和去乙酰化酶（HDACs）等催化酶进行。

乙酰化修饰可调节若干细胞内过程，如基因转录、基因表达、细胞周期、DNA修复、细胞分化等等。

3. 乙酰化修饰与肿瘤乙酰化修饰在调控肿瘤的发生和发展、抗肿瘤治疗等方面也发挥着非常重要的作用。

例如，组蛋白乙酰转移酶（HATs）能够促进肿瘤细胞的转录，并在多种肿瘤中高度表达。

同时，去乙酰化酶（HDACs）的活性也增强了癌细胞的生长和转移，因此HDACs被视为肿瘤治疗的新靶点。

4. 相关研究进展近年来，乙酰化修饰的研究逐渐成为生物学研究的热点。

研究人员不仅在乙酰化修饰的调控机制、乙酰化修饰与疾病之间的关系、使用抗癌药物治疗乙酰化修饰相关的癌症等方面进行了许多研究。

例如，2018年，美国加州大学洛杉矶分校的一位科学家团队发现，一种称为“p300”的组蛋白乙酰转移酶能够调节T细胞的免疫活性，从而与类风湿性关节炎等疾病有关。

此外，多种抗癌药物已经被发现具有抑制乙酰化修饰的能力，例如二苯氨丁酸和替沙单抗等。

5. 结语总的来说，乙酰化修饰在细胞内是一种非常重要的生物化学修饰形式，通过调节蛋白质的结构和功能，产生多种生物学效应，进而影响到多种细胞内physiological process。

蛋白质翻译后修饰对生物体内药代动力学的影响蛋白质是生物体内最基本的分子机器。

它们扮演着各种各样的角色，从基本的代谢功能到细胞信号转导和调控。

生物体内的蛋白质质量和功能取决于它们的化学特性，包括氨基酸序列、折叠状态和化学修饰状态。

这篇文章将讨论蛋白质翻译后修饰对生物体内的药代动力学的影响。

蛋白质的化学结构蛋白质是由一串氨基酸序列组成的长链。

氨基酸的序列决定了蛋白质的三维结构，从而决定了蛋白质的功能。

这个过程通常称为折叠。

大多数蛋白质在折叠过程中形成了一个稳定的三维结构，这个结构通常与它们的功能相匹配。

其中一些蛋白质需要辅助因子或者其他蛋白质来帮助它们正确地折叠。

蛋白质翻译后修饰在蛋白质被翻译出来之后，它们经常会在化学上发生修饰。

这些修饰可以影响它们的稳定性、活性和定位。

常见的修饰包括磷酸化、甲基化、糖基化和乙酰化。

这些修饰可以通过调控蛋白质与其他分子之间的相互作用，从而影响蛋白质的功能。

有些修饰可以使蛋白质变得更加稳定，有些修饰则会导致蛋白质变得不稳定以至于被分解。

这些修饰对药代动力学有重要的影响。

药代动力学药代动力学是研究药物在生物体内的代谢和动力学的学科。

药物的代谢对其药效、毒性和药理学特性具有显著的影响。

在大多数情况下，代谢是通过酶催化的反应进行的。

大多数情况下，这些酶是蛋白质，其中一些蛋白质的活性是受到修饰的影响的。

蛋白质修饰对药代动力学的影响蛋白质的修饰可以影响酶的活性，从而影响药物的代谢速率。

糖基化修饰可以增强肝脏细胞表面上的药物转运蛋白质的识别和结合能力，从而增强药物的清除能力。

乙酰化修饰可以在蛋白质上引入乙酰修饰，从而影响酶的活性。

甲基化修饰可以影响酶的亲和力和稳定性。

总之，各种蛋白质修饰可以影响酶的性质并影响药物的代谢。

结论蛋白质翻译后修饰对药代动力学有着极为重要的影响。

蛋白质的修饰可以影响药物的代谢速率和清除能力，从而影响药物的药效和毒性。

因此，对蛋白质翻译后修饰的研究对于药物设计和开发具有巨大的实际意义。

抗体药物其它翻译后修饰（氧化、脱酰胺）分析抗体药物是一类通过人工合成的抗体来治疗疾病的药物，如单克隆抗体、人工合成的抗体片段、免疫毒素、抗体药物共轭物等。

蛋白质翻译后修饰（PTMs）是指蛋白质在翻译中或翻译后的化学修饰过程，其在细胞分化、蛋白质降解、信号传导以及蛋白质相互作用等细胞过程中起着关键作用。

氧化和脱酰胺也是其中较为重要的两种翻译后修饰，氧化主要影响抗体药物中含有硫的氨基酸，如半胱氨酸等，导致抗体药物的结构和功能改变，从而影响其治疗效果。

抗体药物中天冬酰胺和谷氨酰胺残基的非酶催化脱酰胺作为一种常见的翻译后修饰也时常发生。

抗体药物脱酰胺可能会影响蛋白质的结构、稳定性、折叠和聚集等，从而影响抗体药物的安全性和有效性，因而也成为抗体药物的关键质量属性。

如何测定抗体药物的氧化和脱酰胺等翻译后修饰也成为药物质控过程的重要步骤。

对于抗体药物的氧化修饰而言，通常通过高效液相色谱（HPLC）和质谱（MS）等分析技术进行检测。

通过比较处理前后的抗体药物样本，用HPLC和MS分析硫含有的氨基酸含量的变化，从而确定氧化的程度。

脱酰胺分析方法也类似，脱酰胺反应导致氨基酸质量减少，MS可以检测到这种质量变化。

LC-MS或LC-MS/MS具有更高的灵敏度，是检测PTMs的“金标准”。

生物制品表征其他翻译后修饰（氧化、脱酰胺）分析示意图。

百泰派克生物科技（BTP），采用CNAS和ISO9001双重认证质量控制体系管理实验室，为客户提供符合全球药政法规的药物质量研究服务。

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