单纯性肥胖者血清胆汁酸谱研究

目的探讨单纯性肥胖者血清胆汁酸谱的特征,为阐明胆汁酸引发的能量代谢相关机制和探寻新的肥胖生物治疗靶点提供研究依据。方法利用超高效液相色谱-串联质谱(UPLC-MS/MS)联用方法检测体检人群中10名表观正常对照者、10例超重者和10例单纯性肥胖者血清胆汁酸谱的特征。结果表观正常对照组、超重组和单纯性肥胖组血清中14种胆汁酸亚组分均有表达,其中的石胆酸(LCA)、牛磺胆酸(TCA)、牛磺石胆酸(TLCA)和牛磺熊脱氧胆酸(TUDCA)的表达水平最低;14种胆汁酸亚组分在各组间的差异均无统计学意义(P>0.05);单纯性肥胖组的胆汁酸谱中以甘氨鹅脱氧胆酸(GCDCA)和牛磺鹅脱氧胆酸(TCDCA)增高为主;超重组及单纯性肥胖组血清游离型胆汁酸(FBA)和结合胆汁酸(CBA)水平稍低于表观正常对照组,但差异无统计学意义(P>0.05)。结论单纯性肥胖者血清胆汁酸谱中以GCDCA和TCDCA增高为主,但各种胆汁酸亚组分的表达水平与表观正常者相同。     

超高效液相色谱-串联质谱法同时测定15种胆汁酸的方法分析

目的初步建立同时测定人体血清中15种胆汁酸的超高效液相色谱-串联质谱(LC-MS/MS)的分析方法。方法通过同位素标记的胆汁酸作为内标,使用乙腈对血清中的胆汁酸进行提取,采用Waters BEH C18色谱柱,对15种胆汁酸进行分离。使用串联质谱进行检测,在负离子模式使用多反应监测模式定量分析血清中胆汁酸的浓度。结果 15种胆汁酸在1.0~6 000.0nmol/L范围内线性关系良好,线性相关系数r20.993;目标物的定量限为1.0~10.0nmol/L;低、中、高浓度的平均回收率为97.1%~108.3%,日内、日间平均相对标准偏差小于7.8%。所开发的方法被应用于检测24例健康志愿者的血清标本,健康者的胆汁酸以甘氨酸结合型为主,游离型胆汁酸和牛磺酸结合型胆汁酸浓度相对较低。男性血清中脱氧胆酸浓度显著高于女性,男性血清中甘氨熊脱氧胆酸浓度显著低于女性,差异均有统计学意义(P0.05)。结论 LC-MS/MS法能有效分离并定量检测人血清中15种胆汁酸的水平,其线性范围广、灵敏度高、精密度好,有望作为临床血清15种胆汁酸检测的参考方法。     

ID-LC-MS/MS检测L-色氨酸及其代谢物的方法建立及方法学评价

目的建立同位素稀释液相色谱串联质谱(ID-LC-MS/MS)方法检测血清中L-色氨酸及其代谢物。方法方法学建立及评价。收集2022年11月至2023年1月的华西医院166例健康体检者的血清样本。采用L-色氨酸(Trp)、L-犬尿氨酸(Kyn)和犬尿喹啉酸(KA)的同位素标记物为内标, 通过蛋白沉淀处理血清样本, 应用LC-MS/MS同时检测Trp、Kyn和KA含量。评价该方法的选择性、特异性、线性、检出限(LOD)、定量限(LOQ)、携带污染、精密度、加标回收率、基质效应和稀释一致性。结果 Trp、Kyn和KA的线性相关系数均>0.999, LOD分别为0.10 μmol/L、0.01 μmol/L和1.00 nmol/L, LOQ分别为0.20 μmol/L、0.04 μmol/L和2.00 nmol/L, 批内精密度和批间精密度均<10%, 平均加标回收率与相对基质效应均在100%左右, 超线性范围的样本最多可稀释16倍。健康体检者血清中Trp、Kyn、KA含量、Kyn/Trp和KA/Kyn比值分别为(59.55±10.92)μmol/L、(1.85±0.43)μmol...     

串联质谱技术检测孕妇胆汁酸谱的性能评估及其参考区间建立

目的对基于串联质谱(LC-MS/MS)技术检测胆汁酸谱的方法进行性能评估并建立适合于南京地区孕妇的15种胆汁酸亚型参考区间。方法采用LC-MS/MS技术检测孕中期孕妇血清15种胆汁酸亚型,根据美国临床和实验室标准协会(CLSI)C62-A和美国食品药品监督管理局的生物分析方法验证标准,从定量检出限、准确度、精密度、线性、携带污染率等几个方面进行性能评估;根据CLSI EP28-A3c推荐的方法和程序建立南京地区孕妇孕中期15种胆汁酸亚型的参考区间,用小样本验证法对新建立的20例样本参考区间进行验证。结果 LC-MS/MS技术可同时检测孕妇血清中15种胆汁酸亚组分,最低定量限为标准曲线最低浓度点(S1)浓度,最低检出限为1/4 S1;线性:各种亚型均呈现良好的线性关系,r~2均大于0.99;准确度:各种亚型加标回收试验回收率均为80%～120%,偏倚15%;批内精密度和批间精密度变异系数均小于15%;携带污染率:小于最低定量限的25%;孕中期孕妇参考区间:以石胆酸为例,新的参考区间为0.07～13.46 ng/mL,95%的验证结果落于新的参考区间内。结论 LC-MC/MS技术可以精准、快速地检测胆汁酸谱15种亚型,评估结果符合各项性能验证要求;新建立的胆汁酸谱15种亚型的参考区间适合于南京地区孕中期孕妇。     

液相色谱串联质谱法检测人血清雌酮、雌二醇

目的建立同时测定人血清中雌酮(E1)及雌二醇(E2)水平的液相色谱串联质谱(LC-MS/MS)法,并初步应用于临床血清样品的雌激素检测。方法血清样品经乙酸乙酯提取,丹磺酰氯衍生化后进行LC-MS/MS分析。用Agilent ZORBAX SBC18色谱柱进行线性梯度洗脱,流动相为乙腈(0.05%甲酸)-水(0.05%甲酸),流速为0.3 m L/min。用多重反应离子监测(MRM)正离子模式对血清中的E1、E2进行质谱检测,并根据"生物样品定量分析方法验证指导原则(中国药典,2015)"对该方法的特异性、线性范围、灵敏度、精密度、提取回收率和稳定性等进行评价。用本法对172例健康成年女性血清标本进行E1、E2检测,用百分位数法计算不同月经周期E1、E2的浓度区间。结果 LC-MS/MS法可同时检测人血清中E1、E2的含量,在0.05~10 nmol/L范围内线性关系良好。该法的定量限为0.05 nmol/L,日内与日间不精密度均小于15%,稳定性良好。初步临床应用显示,用LC-MS/MS法计算所得的E1、E2浓度区间符合女性月经周期生理性变化规律。结论 LC-MS/MS法能有效分离并定量检测人血清中E1、E2的浓度水平,其线性范围广、灵敏度高、精密度好,有望作为临床血清雌激素检测的参考方法。     

人血清哇巴因UPLC-MS/MS检测方法的建立和方法比对

目的建立超高效液相色谱串联质谱(UPLC-MS/MS)检测人血清哇巴因的方法。方法采用高特异性的UPLC-MS/MS,以氘标记的哇巴因-d3作为内标。样本采用固相萃取(SPE)前处理方法,以反相色谱柱负离子模式及电喷雾电离源(ESI)检测血清哇巴因水平。对建立的方法进行方法学(基质效应、回收率、准确度、批内精密度、批间精密度及稳定性)验证。采用建立的UPLC-MS/MS方法检测20名体检健康者及40例高血压患者血清哇巴因水平,并与酶联免疫吸附试验(ELISA)进行比较。结果 UPLC-MS/MS检测血清哇巴因的标准曲线范围为0.02～5.0 ng/mL,最低定量检测限(LLOQ)为0.02ng/mL。采用ABN固相萃取小柱进行样本前处理的基质效应较小,且回收率较高,达85%。LLOQ和低值(0.06 ng/mL)、中值(0.6 ng/mL)、高值(4 ng/mL)质控品的准确度分别为108.0%、89.2%、101.0%、103.0%。3个水平质控品的批内变异系数(CV)分别为2.87%、1.95%、0.56%,批间CV分别为5.98%、1.90%、0.75%。样本室温过夜放置16 h及样本前处理后室温放置自动进样器48 h的偏差均15%。采用UPLC-MS/MS检测哇巴因,正常对照者及高血压患者血清中均未检测到哇巴因。采用ELISA测定血清哇巴因,高血压患者为0.096 ng/mL,正常对照者为0.062 ng/mL。UPLC-MS/MS检测5个水平(0.02、0.05、0.10、0.20、0.50 ng/mL)的哇巴因标准品,其测定结果与对应的哇巴因标准品浓度呈正相关,且线性较好(r20.99),准确度较高;而ELISA检测5个水平哇巴因标准品的结果均很接近(0.024 9～0.029 6 ng/mL)。结论建立了检测人血清哇巴因的UPLC-MS/MS方法,未检测到正常人及高血压患者的血清哇巴因。UPLC-MS/MS与ELISA检测血清哇巴因的结果存在较大差异。     

血清醛固酮候选参考测量程序的建立及性能评估

目的建立基于同位素稀释液相色谱-串联质谱(ID-LC-MS/MS)的血清醛固酮候选参考方法。方法以甲基叔丁基醚为萃取剂,采用液液萃取方式进行样本前处理。以醛固酮-2H7为内标,采用电喷雾离子源(ESI)负离子模式建立检测血清醛固酮的ID-LC-MS/MS方法,并对方法的准确度、精密度、灵敏度、线性等基本分析性能进行验证。结果 ID-LC-MS/MS测定血清醛固酮的线性范围为0.08～3.55 nmol/L,检测限和定量限(LOQ)分别为0.012 nmol/L和0.045 nmol/L。批内和批间变异系数(CV)分别为5.0%和4.1%。平均加标回收率为98.52%～100.14%。测定国际临床化学和检验医学联合会参考实验室外部质量评价计划(RELA)样本的结果偏移1.6%。结论建立的测定血清醛固酮的ID-LC-MS/MS方法准确、精密,有望作为测定血清醛固酮的参考方法。     

基于UPLC-MS/MS 建立早产儿血清25-(OH)D3 和3-epi-25-(OH)D3 检测新方法及临床初步应用

目的 建立血清25- 羟维生素D3[25-hydroxyvitamin D3, 25-(OH)D3] 及3-epi-25- 羟维生素D3[3-epi-25-hydroxyvitaminD3, 3-epi-25-(OH)D3] 超高效液相色谱- 串联质谱检测新方法（ultra-performance liquid chromatography-tandem massspectrometry,UPLC-MS/MS）,并在早产儿中开展初步应用。方法 采用液- 液萃取法提取化合物,五氟苯基丙基（pentafluorophenylpropyl,PFPP）色谱柱分离25-(OH)D3 与3-epi-25-(OH)D3;从最低定量限、线性关系、精密度与准确度等四个方面对新建方法进行验证,并对134 例早产儿血清样本进行检测分析。结果 25-(OH)D3 及3-epi-25-(OH)D3 的最低定量限分别为6.05±0.78 nmol/L,1.48±0.20 nmol/L;线性范围3.78 ～ 480.00 nmol/L,1.00 ～ 128.00 nmol/L;相关系数r2 为0.992 2,0.992 8;25-(OH)D3 与3-epi-25-(OH)D3 低、中、高浓度质控品的日内精密度和日间精密度均小于15.00%;回收率109.92%,102.25%,98.76%;97.75%, 95.25%,99.80%。134 例早产儿血清25-(OH)D3 平均浓度22.35±13.28nmol/L,3-epi-25-(OH)D3 平均浓度5.43±4.35 nmol/L;3-epi-25-(OH)D3 占总25-(OH)D3 的平均比例为19.96%±12.08%,范围0.00% ～ 60.62%。以25-(OH)D3 计算,维生素D（Vitamin D, Vit D）缺乏率、不足率、充足率分别为78.36%,19.40%,2.24%;以总25-(OH)D3 计算,Vit D 缺乏率、不足率、充足率分别为65.67%,26.12%,8.21%;二者Vit D 缺乏率及充足率的比较, 差异均有统计学意义（χ2=5.351,1.719,4.823,均P ＜ 0.05）。结论 本研究建立的UPLC-MS/MS检测法性能良好且能精准检测早产儿血清25-(OH)D3 浓度,在早产儿Vit D 评估方面具有较好的应用价值。     

血清胆汁酸LC-MS/MS测定及在老年人血清检测中的应用

目的：建立稳定、有效的血清中所有胆汁酸的液相色谱-串联质谱（LC-MS／MS）测定方法，分析老年人血清胆汁酸谱的特征。方法：建立血清胆汁酸LC-MS／MS定量检测方法，并对方法的灵敏度、精密度、回收率、线性范围等性能指标进行评价；利用该检测方法对10例老年人和15例儿童的空腹血清中所有胆汁酸进行定量检测，分析老年组血清胆汁酸组成特征。结果：该检测体系中，血清中15种胆汁酸和内标在10分钟内完成定量检测，最低检测极限为2～4ng／ml，浓度在3．9～3000ng／ml范围内线性良好，相对回收率为91．95～108．25％，偏移系数为1．71％～10．83％，日内变异度为0．68％～7．05％，日间变异度为2．04％～11．05％；与儿童组相比，老年组血清中胆汁酸总量、疏水性胆汁酸的含量百分较高。结论：所建立的胆汁酸LC-MS／MS检测方法稳定可靠，能满足临床定量检测要求；老年人体内血清胆汁酸谱可能促进胆石症的发生。     

同位素稀释液相色谱串联质谱法测定血清可替宁

目的 建立一种同位素稀释液相色谱串联质谱(ID-LC/MS/MS)测定血清可替宁的方法,以评价不同吸烟状况健康人的吸烟暴露水平分布状况.方法 以[D3]-可替宁作内标,乙腈沉淀蛋白、离心后吸取上清液、氮气挥干、流动相重组,液相分离后进人串联质谱分析;然后,采用多离子反应监测模式,以标准品制作标准曲线,结合同位素内标法定量建立同位素稀释液相色谱串联质谱法.用以对0 68、48.42、94.34、250.95、287.04 μg/L 5个水平血清样本进行5次重复分析,每次每种血清重复分析3份,以考察方法的精密度;同时测定与评价血清样本添加不同浓度标准品的加样回收率和样本在常温、4℃、-80℃保存的稳定性,以及2010年10月至12月期间94名健康志愿者在不同吸烟状况下的血清可替宁分布情况.并用Mann-Whitney U检验分析60名非吸烟、14名戒烟与20名吸烟健康志愿者血清可替宁含量的差异.结果 用ID-LC/MS/MS检测血清可替宁在本试验条件下分离良好,无内源性物质的干扰,具有较好的特异性;血清可替宁、内标峰面积比与可替宁浓度的线性相关系数≥0.9993;测定5个水平血清样本的总变异系数(CV)分别为4.71％、1.40％、1.98％、1.10％和1.03％;批内CV分别为2.19％、0.78％、0.75％、0.65％和0.67％,ID-LC/MS/MS的检测限(LOD)和定量限(LOQ)分别为0.013和0.050 μg/L,具有较高的灵敏度;3次试验的加样回收率范围为99.22％ ～ 102.67％;样本在常温条件下放置2d、4 ℃放置7d以及-80℃冻存保存3个月测定结果的准确度为99.28％～ 100.87％,批间CV均＜5％.检测94名健康人血清可替宁水平呈偏态和尖态分布(偏度2.71,峰度6.65),其中,20名吸烟者的可替宁浓度为116.40 (63.17 ～241.12) μg/L,14名已成烟者为0.67 (0.15～0.95) μg/L,60名非吸烟者为0.22 (0.15 ～0.42) μg/L;已戒烟者(Z=-2.12,P＜0.05)和吸烟者(Z=-6.67,P＜0.001)血清可替宁浓度分别显著高于非吸烟者.结论 建立的ID-LC/MS/MS测定血清可替宁方法操作简便、特异、灵敏,可望在吸烟暴露水平评价及暴露与疾病发生危险的研究中提供有效技术平台.     

Determination of creatine kinase isoenzyme MB activity in serum using immunological inhibition of creatine kinase M subunit activity. Activity kinetics and diagnostic significance in myocardial infarction.

This is a new method for the determination of creatine kinase isoenzyme MB activity in serum. The method uses direct activity measurement of creatine kinase B subunit activity after blocking of CK-M subunit activity by inhibiting antibodies. The test takes no longer than 15 min. The method yields an intra-serial C.V. of 2.0-12.9%, and a C.V. from day to day of 5.5%. The detection limit is 3.4 U/l creatine kinase MB. In the 95 cases with proven myocardial infarction several types of creatine kinase MB activity kinetics could be determined. The percentage of creatine kinase MB of peak CK-total is 6-25%, with a mean of 11.1%. The amount of creatine kinase MB with respect to total CK activity after reinfarction is higher than the amount after initial infarction.     

Dissociable correlates of two classes of retrieval processing in prefrontal cortex

Although substantial evidence suggests that the prefrontal cortex (PFC) implements processes that are critical for accurate episodic memory judgments, the specific roles of different PFC subregions remain unclear. Here, we used event-related functional magnetic resonance imaging to distinguish between prefrontal activity related to operations that (1) influence processing of retrieval cues based on current task demands, or (2) are involved in monitoring the outputs of retrieval. Fourteen participants studied auditory words spoken by a male or female speaker and completed memory tests in which the stimuli were unstudied foil words and studied words spoken by either the same speaker at study, or the alternate speaker. On "general" test trials, participants were to determine whether each word was studied, regardless of the voice of the speaker, whereas on "specific" test trials, participants were to additionally distinguish between studied words that were spoken in the same voice or a different voice at study. Thus, on specific test trials, participants were explicitly required to attend to voice information in order to evaluate each test item. Anterior (right BA 10), dorsolateral prefrontal (right BA 46), and inferior frontal (bilateral BA 47/12) regions were more active during specific than during general trials. Activation in anterior and dorsolateral PFC was enhanced during specific test trials even in response to unstudied items, suggesting that activation in these regions was related to the differential processing of retrieval cues in the two tasks. In contrast, differences between specific and general test trials in inferior frontal regions (bilateral BA 47/12) were seen only for studied items, suggesting a role for these regions in post-retrieval monitoring processes. Results from this study are consistent with the idea that different PFC subregions implement distinct, but complementary processes that collectively support accurate episodic memory judgments.     

俯卧位通气对高海拔地区肺复张治疗无效急性呼吸窘迫综合征患者氧合的影响

目的 探讨俯卧位通气对高海拔地区肺复张术(RM)治疗无效急性呼吸窘迫综合征(ARDS)患者的治疗作用.方法 从海拔2260m的地区医院筛选RM治疗无效的41例ARDS患者[平均氧合指数( PaO2/FiO2)较RM前升高＜20％视为RM无效],依不同病因分为肺内源性ARDS组(ARDSp组)和肺外源性ARDS组(ARDSexp组),每组再按信封法随机分为俯卧位组和仰卧位组,即ARDSp俯卧位组(11例)、ARDSp仰卧位组(9例)、ARDSexp俯卧位组(10例)、ARDSexp仰卧位组(11例).在通气前及通气1、2、3、4h监测动脉血氧分压( PaO2)、PaO2/FiO2、静态顺应性(Cst)、气道阻力(Raw)的变化.结果 通气lh时,ARDSexp俯卧位组PaO2/FiO2( mm Hg,l mm Hg=0.133 kPa)即较通气前显著升高(157.4±40.6比129.3±48.7,P＜0.05),并随通气时间延长呈持续增高趋势,4h达峰值(219.1 ±41.1);且ARDSexp俯卧位组通气3h内PaO2/FiO2较其他3组显著增高,另3组间则差异无统计学意义.ARDSp俯卧位组、ARDSexp俯卧位组通气4h时PaO2/FiO2均较相应仰卧位组显著增高(208.8±39.7比127.4±47.1,219.1±41.1比124.9±50.8,均P＜0.05).4组通气前后Cst无显著改变,各组间差异也无统计学意义.ARDSp俯卧位组通气4h时Raw(cmH2O·L-1·s-1)较通气前显著降低(6.8±1.7比10.7±1.8,P＜0.05),且明显低于其他3组;其他3组各时间点Raw组内及组间比较差异均无统计学意义.结论 俯卧位通气作为ARDS机械通气重要策略之一,可以改善RM无效高原ARDS患者的氧合,为抢救患者赢得宝贵的时间.     

Digital imaging among medical facilities

The Department of Veterans Affairs (VA) in the USA operates a network of 172 medical centres which all utilize a hospital information system (HIS) which has been developed and is currently maintained by the VA. During the past several years, an image management and communication module has been developed, installed and clinically utilized at the Washington DC and Maryland VA Medical Centres. This image management and communication system, referred to as the decentralized hospital computer program (DHCP) imaging system, is fully integrated with a commercial picture archiving and communication system (PACS). The system is utilized to capture, archive, and display all images generated within the hospital including radiology, nuclear medicine, pathology, endoscopy, bronchoscopy, and dermatology, intraoperative photographs, ECG data, and a limited number of paper documents. The ultimate goal of the project is to have all patient text and image data available at any clinical workstation to any authorized user anywhere within the network of medical centres. Clinical requirements for an imaging workstation include ease of use, rapid and reliable access to the complete set of patient information, and images which are of acceptable quality to meet the requirements of the user and the subspecialty. Patient confidentiality and data security must be safeguarded at all times. Integration of the images with the remainder of the patient's database was found to be critical to the success of the project. The experience at the Washington and Maryland facilities suggests that an imaging system that is successfully integrated with a hospital information system can provide substantial clinical and economic benefits both within and among medical centres. Clinical acceptance and utilization of the system has been excellent, particularly in diagnostic radiology where DHCP Imaging has been interfaced to a commercial PAC system. Based upon this initial experience, the VA has begun to deploy the system throughout its large network of medical centres.     

Myocardial elastography at both high temporal and spatial resolution for the detection of infarcts

Myocardial elastography is a novel method for noninvasively assessing regional myocardial function, with the advantages of high spatial and temporal resolution and high signal-to-noise ratio (SNR). In this paper, in-vivo experiments were performed in anesthetized normal and infarcted mice (one day after left anterior descending coronary artery [LAD] ligation) using a high-resolution (30 MHz) ultrasound system (Vevo 770, VisualSonics Inc., Toronto, ON, Canada). Radiofrequency (RF) signals of the left ventricle (LV) in longitudinal (long-axis) view and the associated electrocardiogram (ECG) were simultaneously acquired. Using a retrospective ECG gating technique, 2-D full field-of-view RF frames were acquired at an extremely high frame rate (8 kHz) that resulted in high-quality incremental displacement and strain estimation of the myocardium. The incremental results were further accumulated to obtain the cumulative displacements and strains. Two-dimensional and M-mode displacement images and strain images (elastograms), as well as displacement and strain profiles as a function of time, were compared between normal and infarcted mice. Incremental results clearly depicted cardiac events including LV contraction, LV relaxation and isovolumetric phases in both normal and infarcted mice, and also evidently indicated reduced motion and deformation in the infarcted myocardium. The elastograms indicated that the infarcted regions underwent thinning during systole rather than thickening, as in the normal case. The cumulative elastograms were found to have higher elastographic SNR (SNR(e)) than the incremental elastograms (e.g., 10.6 vs. 4.7 in a normal myocardium, and 6.0 vs. 2.4 in an infarcted myocardium). Finally, preliminary statistical results from nine normal (m = 9) and seven infarcted (n = 7) mice indicated the capability of the cumulative strain in differentiating infracted from normal myocardia. In conclusion, myocardial elastography could provide regional strain information at simultaneously high temporal (>/=0.125 ms) and spatial ( approximately 55 microm) resolution as well as high precision ( approximately 0.05 microm displacement). This technique was thus capable of accurately characterizing normal myocardial function throughout an entire cardiac cycle, at the same high resolution, and detecting and localizing myocardial infarction in vivo.     

Clinical Pharmacokinetics of Morphine

Morphine, the most widely used mu-opioid analgesic for acute and chronic pain, is the standard against which new analgesics are measured. A thorough understanding of the pharmacokinetics of morphine is required in order to safely and effectively use this analgesic in a wide variety of patients with different levels of organ function. A MEDLINE search was conducted to identify literature published between 1966 and January 2002 relevant to the pharmacokinetics of morphine. These publications were reviewed and the literature summarized regarding unique and clinically important elements of morphine disposition relative to its parenteral administration (including intravenous, intramuscular, subcutaneous, epidural and intrathecal administration), absorption profile (immediate release, controlled release, and sublingual/buccal, and rectal administration), distribution, and its metabolism/ excretion. Special populations, including infants, elderly, and those with renal/liver failure, have a unique morphine pharmacokinetic profile that must be taken into account in order to maximize analgesic efficacy and reduce the risk of adverse events.