艾司氯胺酮联合舒芬太尼术后镇痛对老年腹腔镜结肠癌根治术患者细胞免疫功能、疼痛因子和认知功能的影响

摘要 目的：观察艾司氯胺酮联合舒芬太尼术后镇痛对老年腹腔镜结肠癌根治术患者疼痛因子、细胞免疫功能、认知功能的影响。方法：纳入武汉科技大学附属天佑医院2021年1月~2022年10月期间收治的老年腹腔镜结肠癌根治术患者156例。根据随机数字表法将患者分为对照组（枸橼酸舒芬太尼注射液术后镇痛）和研究组（盐酸艾司氯胺酮注射液联合枸橼酸舒芬太尼注射液术后镇痛）,各78例。对比两组静脉自控镇痛泵（PCIA）有效按压次数、Ramsay镇静评分、疼痛视觉模拟评分（VAS）、细胞免疫功能、疼痛因子、认知功能和不良反应发生率。结果：研究组的PCIA有效按压次数少于对照组（P<0.05）;术后24 h、术后48 h,研究组VAS评分低于对照组,Ramsay镇静评分高于对照组（P<0.05）。术后48 h,研究组β-内啡肽（β-EP）高于对照组,P物质（SP）、前列腺素E₂（PEG₂）低于对照组（P<0.05）。术后48 h,研究组CD8⁺低于对照组,CD3⁺、CD4⁺、CD4⁺/CD8⁺高于对照组（P<0.05）。研究组术后12 h、术后24 h、术后48 h MMSE评分高于对照组（P<0.05）。两组不良反应发生率组间对比未见统计学差异（P>0.05）。结论：艾司氯胺酮联合舒芬太尼术后镇痛用于老年腹腔镜结肠癌根治术患者,可获得较好的镇静、镇痛效果,可减少PCIA有效按压次数,减轻免疫抑制,降低疼痛因子过度分泌,改善认知功能。     

右美托咪定联合舒芬太尼术后镇痛对老年肺癌患者T细胞亚群、血清炎性因子和疼痛介质指标的影响

摘要 目的：观察右美托咪定联合舒芬太尼术后镇痛对老年肺癌患者T细胞亚群、血清炎性因子和疼痛介质指标的影响。方法：选取2017年7月~2020年12月期间200例我院收治的行肺癌根治术的老年患者,按随机数字表法分为研究组（n=100）、对照组（n=100）。对照组术后镇痛选用舒芬太尼,研究组术后镇痛选用右美托咪定联合舒芬太尼,观察两组患者视觉模拟评分法（VAS）评分和Ramsay镇静评分、外周血T细胞亚群、血清炎性因子和疼痛介质指标、不良反应。结果：两组术后6 h、12 h、24 h、48 h的Ramsay镇静评分、VAS评分均较术后1 h下降（P<0.05）,且研究组以上时间点Ramsay镇静评分高于对照组,而VAS评分低于对照组（P<0.05）。两组术后24 h血清干扰素-γ（IFN-γ）、白细胞介素-6（IL-6）升高,但研究组术后24 h血清IFN-γ、IL-6低于对照组（P<0.05）。两组术后24 h外周血CD8⁺升高,CD3⁺、CD4⁺、CD4⁺/CD8⁺降低（P<0.05）,但术后24 h研究组CD8⁺低于对照组,CD3⁺、CD4⁺、CD4⁺/CD8⁺高于对照组（P<0.05）。术后24 h两组血清β-内啡肽（β-EP）、P物质（SP）以及一氧化氮（NO）水平均升高,但研究组低于对照组（P<0.05）。两组不良反应发生率组间对比无统计学差异（P>0.05）。结论：右美托咪定联合舒芬太尼用于老年肺癌患者术后镇痛,镇痛、镇静效果确切,同时可减轻免疫抑制及炎性反应,且安全性高。     

羟考酮联合右美托咪定术后镇痛对腹腔镜下结肠癌根治术患者炎性因子、T细胞亚群和认知功能的影响

摘要 目的：探讨羟考酮联合右美托咪定术后镇痛对腹腔镜下结肠癌根治术患者炎性因子、T细胞亚群和认知功能的影响。方法：选取我院于2013年1月~2019年12月期间收治的80例行腹腔镜下结肠癌根治术的患者,采用随机数字表法将患者分为A组和B组,各40例,A组给予舒芬太尼联合右美托咪定术后镇痛,B组给予羟考酮联合右美托咪定术后镇痛,对比两组围术期指标、炎性因子、T细胞亚群和认知功能。结果：B组自主呼吸恢复时间、定向力恢复时间、拔管时间短于A组,自控镇痛泵（PCA）总按压次数少于A组,PCA有效按压次数多于A组（P<0.05）。两组术前、术后1 d、术后3 d的白介素-6（IL-6）、C反应蛋白（CRP）、肿瘤坏死因子-α（TNF-α）水平呈先升高后降低趋势（P<0.05）,B组术后1 d、术后3 d的IL-6、CRP、TNF-α水平低于A组（P<0.05）。两组术前、术后1 d、术后3 d 的CD3⁺、CD4⁺、CD4⁺/CD8⁺呈先降低后升高趋势,CD8⁺呈先升高后降低趋势（P<0.05）,B组术后1 d、术后3d CD3⁺、CD4⁺、CD4⁺/CD8⁺高于A组,CD8⁺则低于A组（P<0.05）。两组术后1 d、2 d、3 d简易精神状态检查表（MMSE）评分呈升高趋势（P<0.05）,B组术后1 d、2 d、3 d的MMSE评分高于A组（P<0.05）。结论：腹腔镜下结肠癌根治术患者采用羟考酮联合右美托咪定术后镇痛,可减轻患者炎性反应及免疫抑制,同时还可减轻其认知功能损伤,促进其术后恢复。     

超声引导下前锯肌平面阻滞对乳腺癌改良根治术患者血清疼痛介质、血流动力学及免疫功能的影响

摘要 目的：探讨超声引导下前锯肌平面（SP）阻滞对乳腺癌改良根治术患者血流动力学、血清疼痛介质、免疫功能的影响。方法：选择2020年9月-2022年5月期间我院收治的120例乳腺癌改良根治术患者,采用随机双盲对照原则将患者分为对照组和研究组,各为60例。对照组患者接受常规麻醉,研究组患者在常规麻醉基础上接受超声引导下SP阻滞。观察两组患者的镇静镇痛效果,对比两组患者疼痛介质、血流动力学及免疫功能的变化情况,记录两组围术期间不良反应发生情况。结果：研究组手术开始后10 min、术毕心率（HR）、平均动脉压（MAP）高于对照组（P<0.05）。研究组术后24 h CD8⁺低于对照组,CD3⁺、CD4⁺、CD4⁺/CD8⁺高于对照组（P<0.05）。研究组术后24 h神经肽Y（NPY）、前列腺素E2（PGE2）、P物质（SP）低于对照组（P<0.05）。研究组术后24 h疼痛视觉模拟评分（VAS）评分低于对照组,Ramsay镇静评分高于对照组（P<0.05）。两组不良反应发生率对比,无统计学差异（P>0.05）。结论：超声引导下SP阻滞可加强乳腺癌改良根治术患者的镇静镇痛效果,维持血流动力学稳定,降低血清疼痛介质,减轻免疫抑制。     

腹腔镜与开腹胃楔形切除术对GIST患者营养状况、T细胞亚群和预后的影响

摘要 目的：探讨腹腔镜与开腹胃楔形切除术对胃间质瘤（GIST）患者营养状况、T细胞亚群和预后的影响。方法：回顾性分析2013年1月~2014年2月期间我院收治的GIST患者97例的临床资料,根据手术方式的不同将患者分为对照组（n=47,开腹胃楔形切除术）和研究组（n=50,腹腔镜胃楔形切除术）,对比两组患者手术相关指标、营养状况、T细胞亚群、预后情况。结果：研究组住院时间、肛门排气时间、切口长度、手术时间短于对照组,术中出血量少于对照组（P<0.05）。两组患者术后7 d前白蛋白、转铁蛋白、白蛋白均降低,但研究组高于对照组（P<0.05）。两组术后7 d的 CD4⁺/CD8⁺、CD3⁺、CD4⁺较术前下降,CD8+较术前升高（P<0.05）;研究组术后7 d 的CD4⁺/CD8⁺、CD3⁺、CD4⁺高于对照组,CD8⁺则低于对照组（P<0.05）。研究组并发症总发生率低于对照组（P<0.05）;两组术后复发率、5年生存率比较无统计学差异（P>0.05）。结论：与开腹胃楔形切除术相比,GIST患者采用腹腔镜胃楔形切除术治疗的远期预后效果相当,可有效改善围术期相关指标,对患者营养状况、T细胞亚群的影响较轻,且可减少术后并发症的发生率。     

香砂六君子汤辅助化疗对腹腔镜结肠癌根治术后患者细胞免疫功能和血清肿瘤标志物的影响

摘要 目的：观察香砂六君子汤辅助化疗对腹腔镜结肠癌根治术后患者细胞免疫功能和血清肿瘤标志物的影响。方法：前瞻性选取2019年3月-2021年3月期间来南京医科大学附属江宁医院接受治疗的85例结肠癌患者,均接受腹腔镜结肠癌根治术治疗。分组方法选用随机数字表法,分为对照组（给予化疗治疗,n=42）和研究组（给予香砂六君子汤辅助化疗治疗,n=43）。对比两组疗效、中医证候积分、细胞免疫功能、血清肿瘤标志物和不良反应发生率。结果：与对照组比较,研究组的临床总有效率明显升高（P<0.05）。两组不良反应发生率组间对比无差异（P>0.05）。研究组治疗结束后CD3⁺、CD4⁺/CD8⁺、CD4⁺高于对照组（P<0.05）。研究组治疗结束后血清癌胚抗原（CEA）、癌抗原125（CA125）、甲胎蛋白（AFP）、CD8⁺水平低于对照组（P<0.05）。研究组治疗结束后腹痛、食少纳呆、腹胀、大便脓血评分低于对照组（P<0.05）。结论：香砂六君子汤辅助化疗治疗腹腔镜结肠癌根治术后患者,可有效促进症状改善,阻止肿瘤细胞扩散,减轻免疫抑制,具有一定的临床价值。     

右美托咪定联合舒芬太尼术后镇痛对卵巢癌根治术患者细胞免疫功能和炎症应激反应的影响

摘要 目的：探讨右美托咪定联合舒芬太尼术后镇痛对卵巢癌根治术患者细胞免疫功能和炎症应激反应的影响。方法：根据随机数字表法将2020年2月至2023年2月期间陕西省肿瘤医院120例择期行卵巢癌根治术的患者分为对照组（n=60，术后镇痛药物选用舒芬太尼）和研究组（n=60，术后镇痛药物选用右美托咪定联合舒芬太尼）。对比两组镇静（Ramsay镇静评分）、细胞免疫功能[CD3⁺、CD4⁺、CD8⁺、CD4⁺/CD8⁺]、镇痛情况[视觉模拟评分法（VAS）]、不良反应、炎症应激反应[白细胞介素-6（IL-6）、肿瘤坏死因子-α（TNF-α）、皮质醇（Cor）和去甲肾上腺素（NE）]变化情况。结果：与对照组术后6 h、12 h、24 h、48 h 相比，研究组同时间点VAS评分更低，Ramsay镇静评分更高（P<0.05）。与对照组术后24 h相比，研究组同时间点CD3⁺、CD4⁺、CD4⁺/CD8⁺更高，CD8⁺更低（P<0.05）。两组不良反应发生率组间对比未见差异（P>0.05）。与对照组术后24 h相比，研究组同时间点IL-6、TNF-α、Cor、NE更低（P<0.05）。结论：右美托咪定联合舒芬太尼用于卵巢癌根治术患者术后镇痛，镇静、镇痛效果显著，同时还可减轻机体炎症应激反应，缓解免疫抑制。     

瑞芬太尼联合右美托咪定对乳腺癌根治术患者镇痛效果及围术期T淋巴细胞亚群的影响

摘要 目的：研究瑞芬太尼联合右美托咪定在乳腺癌根治术患者手术过程中的镇痛效果,以及围手术期对患者外周血T淋巴细胞亚群的影响。方法：收集2018年到2020年进行根治术手术的68例乳腺癌患者作为研究对象,随机数表法分为对照组和研究组,各34例。对照组给予瑞芬太尼进行麻醉诱导的维持,研究组患者给予瑞芬太尼和右美托咪定进行麻醉诱导和维持。比较两组患者麻醉时间、手术时间、手术出血量,术后苏醒时间、拔管时间以及不良反应发生率,并比较两组患者手术后2 h、8 h和24 h VAS和Ramsay评分以及麻醉诱导前、术中1 h和术后24 h外周血T淋巴细胞亚群变化。结果：两组患者年龄、麻醉时间、手术时间、手术出血量以及手术后2 h、8 h和24 h VAS和Ramsay评分无显著差异（P>0.05）;研究组患者术后苏醒时间、拔管时间以及不良反应发生率均显著低于对照组患者（P<0.05）。麻醉诱导前,两组患者外周血CD3⁺、CD4⁺、CD8⁺及CD4⁺/CD8⁺T淋巴细胞比例无显著差异（P>0.05）;手术中1 h和术后24 h,研究组患者外周血CD3⁺、CD4⁺以及CD4⁺/CD8⁺细胞比例均高于对照组患者,而外周血CD8⁺细胞比例低于对照组患者,差异均显著具体统计学意义（P<0.05）。结论：乳腺癌根治术患者使用瑞芬太尼联合右美托咪定进行麻醉诱导和维持不会影响患者镇痛效果,但可以降低患者术后不良反应发生率,并影响患者围术期T淋巴细胞免疫功能。     

右美托咪定联合地塞米松对结直肠癌患者苏醒质量、应激反应和外周血T细胞亚群的影响

摘要 目的：探讨右美托咪定联合地塞米松对结直肠癌患者苏醒质量、应激反应和外周血T细胞亚群的影响。方法：选择2020年4月~2021年3月期间我院收治的结直肠癌患者132例,采用随机数字表法分为对照组（右美托咪定,n=66）和研究组（右美托咪定联合地塞米松,n=66）。观察两组血流动力学、苏醒质量、应激反应、T细胞亚群和不良反应。结果：研究组给药后10 min（T1）~出手术室时（T4）时间点平均动脉压（MAP）、心率（HR）低于对照组（P<0.05）。研究组T1~T4时间点去甲肾上腺素（NE）、肾上腺素（E）较对照组低（P<0.05）。两组睁眼时间、术后自主呼吸恢复时间、拔管时间组间对比无差异（P>0.05）。研究组术后3 d CD3⁺、CD4⁺、CD4⁺/CD8⁺高于对照组,CD8⁺低于对照组（P<0.05）。两组不良反应发生率组间对比无差异（P>0.05）。结论：右美托咪定联合地塞米松用于结直肠癌患者,可保持良好的苏醒质量,减轻机体应激反应和免疫抑制,改善血流动力学波动。     

葡萄糖酸锌颗粒联合消旋卡多曲颗粒对轮状病毒性肠炎患儿血浆炎性因子、心肌酶指标及免疫功能的影响

摘要 目的：探讨葡萄糖酸锌颗粒联合消旋卡多曲颗粒对轮状病毒性肠炎患儿血浆炎性因子、心肌酶指标及免疫功能的影响。方法：选取2017年2月~2019年7月期间于我院门诊就诊的轮状病毒性肠炎患儿97例,根据随机数字表法分为对照组（n=48）和研究组（n=49）,在常规治疗的基础上对照组患儿给予消旋卡多曲颗粒治疗,研究组在对照组的基础上联合葡萄糖酸锌颗粒治疗,比较两组患儿疗效、血浆炎性因子[白介素-6（IL-6）、肿瘤坏死因子-α（TNF-α）]、血清心肌酶指标[乳酸脱氢酶（LDH）、磷酸肌酸激酶同工酶（CK-MB）和磷酸肌酸激酶（CK）]及免疫功能指标（CD4⁺、CD8⁺、CD4⁺/CD8⁺）的变化情况,记录两组治疗期间不良反应发生情况。结果：研究组治疗7 d后的临床总有效率为91.84%（45/49）,高于对照组的75.00%（36/48）（P<0.05）。两组治疗7 d后血浆IL-6、TNF-α水平均下降,且研究组低于对照组（P<0.05）。两组治疗7d后血清LDH、CK、CK-MB水平均下降,且研究组低于对照组（P<0.05）。两组治疗7 d后CD8⁺下降,且研究组低于对照组（P<0.05）;CD4⁺、CD4⁺/CD8⁺升高,且研究组高于对照组（P<0.05）。两组不良反应发生率对比未见统计学差异（P>0.05）。结论：葡萄糖酸锌颗粒联合消旋卡多曲颗粒治疗轮状病毒性肠炎患儿疗效显著,可改善患儿炎性因子、心肌酶指标,提升患儿免疫功能,且未见严重不良反应发生。     

六种藓类植物茎的比较解剖学研究

通过对6种藓类植物,即褶叶青藓(Brachythecium salebrosum(Web.et Mohr.)B.S.G.)、湿地匐灯藓(Plagiomnium acutum(Lindb.)Kop.)、侧枝匐灯藓(Plagiomnium maximoviczii(Lindb.)Kop.)、大凤尾藓(Fissidensnobilis Griff.)、大羽藓(Thuidium cymbifolium(Doz.et Molk.)B.S.G.)和大灰藓(Hypnum plumaeforme Wils.)嫩茎和老茎的石蜡切片和显微观察发现,同一藓类植株的嫩茎和老茎,茎结构稳定,不同种藓类植物茎横切面具有不同特征.植物体茎横切面形状、表层细胞的层数、细胞大小和细胞壁厚薄、皮层细胞大小和形状、中轴的有无以及比例等特征可以作为藓类植物的分科分类依据之一.     

Photoregulation of seed germination of wild-type and of an aurea-mutant of tomato

Seed germination of an aurea mutant of tomato ( Lycopersicon esculentum Mill.) is promoted by continuous irradiation with red, far-red or long-wavelength far-red (758 nm) light as well as by cyclic irradiations (5 min red or 5 min far-red/25 min darkness). Far-red light applied immediately after each red does not change the germination behaviour. Seed germination of the isogenic wild-type, cv. UC-105, is promoted by continuous and cyclic red light while it is inhibited by continuous and cyclic far-red light and by continious 758 nm irradiation. Far-red irradiation reverses almost completely the promoting effect of red light. The promoting effect (in the aurea mutant) and the inhibitory effect (in the wild-type) of continuous far-red light do not show photon fluence rate dependency above 20 nmol m⁻² s⁻¹. It is concluded that phytochrome controls tomato seed germination throgh low energy responses in both the wild type and the au mutant. The promoting effect of continuous and cyclic far-red light in the au mutant can be attributed to a greater sensitivity to P_fr.     

Cause of Senescence of Nine Sorts of Flowers

The levels of endogenous phytohormones and respiratory rate in nine sorts of flowers such as Cymbidium faberi Rolfe, Nopalxochia ackermannii Kunth and others were investigated both at full bloom and senescence and meanwhile the effect of exogenous phytohormones on prolonging the blossoms and promoting ethylene production were tested. There is a high content of endogenous ethylene in all the long-lived flowere, about 3–16 folds higer than the short-lived ones. There is a high level of ABA at full blooming flowers of short-lived flowers, in which there is no or only some cytokinins in it, but the ratio of CTK (6BA+zeatin)/ABA is smaller(l.7). The endogenous ABA reached a much higher level at senescence in all nine sorts of flowers, so it is reasonable to consider that it is ABA which plays an important role of regulation in controlling flower's senescence. There is a much higher level of GA3 and zeatin in the long-lived flowers which is not demonstrated in the shortlived ones. The respiratory rate is one of the factors controtling the longevity of flowers, but it does not play a decided role. Application of 6BA and zeatin prolongs distinctly orchid’s longevity, however exogenous IAA through the promotive action on ethylene production, evidently extends the longevity of the flowers of the Nopalxochia ackermannii Kunth.     

龙胆科药用植物化学成分的研究现状

龙胆科植物在我国的分布范围很广,且多数为药用植物,其多数种属的药用植物,至今其化学成分尚未被系统研究。综述了目前龙胆科药用植物的化学成分的研究现状及一般提取方法,对近年来发现的环烯醚萜及裂环烯醚萜类化合物进行了总结,为本科药用植物的更深入研究提供了参考。     

Interconnection of parameters of regulation system of lipid peroxidation and of morphophysiological parameters of mouse liver

A complex analysis of seasonal fluctuations of the mean group parameters of the system of regulation of lipid peroxidation has been performed in liver of Balb/c mice. Association of lipid characteristics and morphophysiological parameters is studied in the Balb/c mouse liver. An inter-connection is revealed between the liver index and the amount of lysoforms of phospholipids, the scale and character of the interconnection differing essentially depending on proportion of phos-phatidylcholine in mouse liver phospholipids.     

The effects of glutamine of the maintenance of embryogenic cultures of Cryptomeria japonica

Summary Embryogenic tissues of sugi (Cryptomeria japonica) were induced on a modified Campbell and Durzan (CD) medium containing 1 μM 2,4-dichlorophenoxyacetic acid (2,4-D) and 600 mg l⁻¹ glutamine, and subcultured in the medium of the same composition for over 1 yr. This resulted in a mixed culture of embryogenic and non-embryogenic cells. When embryogenic cells were isolated and cultured independently, their capacity to form embryogenic aggregates was lost. Thus, the non-embryogenic cells present within a mixed culture system were essential to the formation of embryogenic aggregates. When embryogenic tissues were isolated and cultured independently on a high glutamine-containing (2400 mg l⁻¹) medium, dry weights and endogenous levels of glutamine increased, and the tissue could generate a large number of embryogenic aggregates. Amino acid analysis of embryogenic and non-embryogenic cells from the maintenance culture indicated a higher level of glutamine was present in the latter. The high endogenous level of glutamine in the non-embryogenic portion of mixed cell masses may be the supplier of glutamine for maintaining the embryogenic property of the tissues.     

Specificity of action of piperidylcholine derivatives as substrates of cholinesterases of various origin

The review deals with study of enzymologic properties of a novel highly specific acetylcholinesterase substrate, N-(β-acetoxyethyl) piperidinium iodomethylate (“piperidylcholine”), and its 30 derivatives that were tested as effectors of cholinesterases of mammals and various species of Pacific squids. It was proven for the first time that responsible for specificity of action was structure of cyclic ammonium grouping of the alcohol part of molecule of the ester substrate. Analysis of specificity is performed based on enzymatic hydrolysis parameters—activity of catalytic center of cholinesterases and bimolecular constant of the reaction rate that are determined at optimal and low substrate concentrations. Among the specially synthesized group of thioester compounds there is revealed one more highly specific acetylcholinesterase substrate—N-(β-acetoxyethyl) piperidinium.     

Physiological characteristics of various species of strains of carboxydobacteria

Seven strains of aerobic carbon monoxide-oxidizing bacteria (carboxydebacteria) when growing on CO as sole source of carbon and energy had doubling times which ranged from 12–42 h. The activity profiles obtained after discontinuous sucrose density gradient centrifugation indicated that the CO-oxidizing enzymes are soluble and the hydrogenases are membrane-bound in all strains examined. The CO-oxidizing enzymes of Pseudomonas carboxydohydrogena, Pseudomonas carboxydoflava, Comamonas compransoris, and the so far unidentified strains OM2, OM3, and OM4 had a molecular weight of 230,000; that of Achromobacter carboxydus amounted to 170,000. The molecular weights of the CO-oxidizing and H₂-oxidizing enzymes turned out to be identical. The cell sonicates were shown to catalyze the oxidation of both CO and H₂ with methylene blue, thionine, phenazine methosulfate, toluylene blue, dichlorophenolindophenol, cytochrome c or ferricyanide as electron acceptors. Methyl viologen, benzyl viologen, FAD⁺, FMN⁺, and NAD(P)⁺ were not reduced. The spectrum of electron acceptors was identical for all strains tested. Neither free formate, hydrogen nor oxygen gas were involved in the CO-oxidation reaction. Methylene blue was reduced by CO at a 1:1 molar ratio. The results indicate that CO-oxidation by carboxydobacteria is catalyzed by identical or similar enzymes and that the reaction obeys the equation CO+H₂OCO₂+2H⁺+2e^- as previously shown for Pseudomonas carboxydovorans.Dedicated to Otto Kandler remembering almost three decades of enjoyable cooperation     

Modulation of allostery of pyruvate kinase by shifting of an ensemble of microstates

Since the introduction of the concepts of allostery about four decades ago, much advancement has been made in elucidating the structure-function correlation in allostery. However, there are still a number of issues that remain unresolved. In this review we used mammalian pyruvate kinase (PK) as a model system to understand the role of protein dynamics in modulating cooperativity. PK has a triosephosphate isomerase (TIM)(α/β)₈ barrel structural motif. PK is an ideal system to address basic questions regarding regulatory mechanisms about this common (α/β)₈ structural motif. The simplest model accounting for all of the solution thermodynamic and kinetic data on ligand-enzyme interactions involves two conformational states, inactive E^T and active E^R. These conformational states are represented by domain movements. Further studies provide the first evidence for a differential effect of ligand binding on the dynamics of the structural elements, not major secondary structural changes. These data are consistent with our model that allosteric regulation of PK is the consequence of perturbation of the distribution of an ensemble of states in which the inactive E^T and active E^R represent the two extreme end states. Sequence differences and ligands can modulate the distribution of states leading to alterations of functions. The future work includes: defining the network of functionally connected residues; elucidating the chemical principles governing the sequence differences which affect functions; and probing the nature of mutations on the stability of the secondary structural elements, which in turn modulate allostery.