慢性牙周炎患者血清CGRP、PGE2、CCL20与牙周临床指标和Th17/Treg失衡的相关性分析

摘要 目的：探讨慢性牙周炎（CP）患者血清降钙素基因相关肽（CGRP）、前列腺素E₂（PGE₂）、C-C基序趋化因子配体20（CCL20）与牙周临床指标和辅助性T细胞17/调节性T细胞（Th17/Treg）失衡的相关性。方法：选取2018年3月～2022年1月本院收治的92例CP患者,根据病情严重程度分为轻度组28例、中度组33例、重度组31例。检查患者牙周临床指标,采用酶联免疫吸附法检测血清CGRP、PGE₂、CCL20水平,流式细胞术检测外周血Th17、Treg百分比并计算Th17/Treg。比较3组血清CGRP、PGE₂、CCL20水平和牙周临床指标及外周血Th17、Treg、Th17/Treg,采用Pearson相关系数分析CP患者血清CGRP、PGE₂、CCL20水平与牙周临床指标和Th17/Treg的相关性。结果：轻度组、中度组、重度组血清CGRP水平和外周血Treg比例依次降低,血清PGE₂、CCL20水平和探诊深度（PD）、出血指数（BI）、附着丧失（AL）、菌斑指数（PLI）及外周血Th17比例、Th17/Treg依次升高（P＜0.05）。Pearson相关系数显示,CP患者血清CGRP水平与PD、BI、AL、PLI、Th17/Treg呈负相关,PGE₂、CCL20水平与PD、BI、AL、PLI、Th17/Treg呈正相关（P＜0.05）。结论：血清CGRP、PGE₂、CCL20水平与CP患者牙周临床指标和Th17/Treg失衡密切相关,可能是CP发生发展的关键因子。     

龈沟液Chemerin、APN、25(OH)D3与伴2型糖尿病的慢性牙周炎患者牙周指标和Th17/Treg失衡的关系

摘要 目的：探讨龈沟液趋化素（Chemerin）、脂联素（APN）、25-羟维生素D3 [25(OH)D3]与伴2型糖尿病（T2DM）的慢性牙周炎（CP）患者牙周指标和Th17/Treg失衡的关系。方法：选择2021年1月至2022年1月我院口腔科门诊接诊的125例伴T2DM的CP患者,根据CP病情严重程度分为轻度组（42例）、中度组（53例）和重度组（30例）。检测龈沟液中Chemerin、APN、25(OH)D₃水平以及外周血中Th17细胞占比、Treg细胞占比,计算Th17/Treg比值,记录出血指数（SBI）、菌斑指数（PLI）、附着丧失（AL）、牙周袋探诊深度（PD）。分析龈沟液中Chemerin、APN、25(OH)D₃与牙周指标、外周血Th17/Treg的相关性。结果：重度组龈沟液 Chemerin水平和外周血中Th17细胞占比、Th17/Treg比值、PLI、SBI、AL、PD高于中度组和轻度组（P＜0.05）,龈沟液APN、25(OH)D₃水平,外周血Treg细胞占比低于中度组和轻度组（P＜0.05）。龈沟液 Chemerin与PLI、SBI、AL、PD、外周血Th17细胞占比、Th17/Treg比值呈正相关（P＜0.05）,与Treg细胞占比呈负相关（P＜0.05）;龈沟液APN、25(OH)D₃与PLI、SBI、AL、PD、外周血中Th17细胞占比、Th17/Treg比值呈负相关（P＜0.05）,与Treg细胞占比呈正相关（P＜0.05）。结论：伴T2DM 的CP患者龈沟液中Chemerin水平增高,APN、25(OH)D₃水平降低,且与牙周指标和Th17/Treg失衡有关。     

龈沟液miR-155、miR-223表达水平与慢性牙周炎伴2型糖尿病患者牙周临床指标、口腔龈下菌群以及Th17/Treg失衡的相关性分析

摘要 目的：探讨龈沟液miR-155、miR-223表达水平与慢性牙周炎伴2型糖尿病（T2DM）患者牙周临床指标、口腔龈下菌群以及外周血辅助性T细胞17（Th17）/调节性T细胞（Treg）失衡的相关性。方法：选择2018年1月至2022年1月安徽理工大学第一附属医院口腔科收治的86例慢性牙周炎患者,根据是否伴T2DM将患者分为慢性牙周炎伴T2DM组15例和单纯慢性牙周炎组71例,另选择65例健康体检志愿者为对照组。检测龈沟液miR-155、miR-223表达水平,口腔龈下菌群以及外周血Th17细胞占比、Treg细胞占比、血清白细胞介素（IL）-17、转化生长因子-β（TGF-β）水平。Pearson相关分析龈沟液miR-155、miR-223表达水平与牙周临床指标、口腔龈下菌群、外周血Th17/Treg以及血清IL-17、TGF-β的相关性。结果：慢性牙周炎伴T2DM组、单纯慢性牙周炎组龈沟液miR-155、miR-223表达水平高于对照组（P＜0.05）,且慢性牙周炎伴T2DM组高于单纯慢性牙周炎组（P＜0.05）。慢性牙周炎伴T2DM组龈沟出血指数（SBI）、菌斑指数（PLI）、探诊深度（PD）、附着丧失（AL）、牙龈卟啉单胞菌、二氧化碳噬纤维菌、中间普氏菌、变黑普氏菌数量、外周血Th17细胞占比、Th17/Treg比值、血清IL-17水平高于单纯慢性牙周炎组（P＜0.05）,外周血Treg细胞占比低于单纯慢性牙周炎组（P＜0.05）。龈沟液miR-155、miR-223表达水平与PLI、SBI、AL、PD、牙龈卟啉单胞菌、二氧化碳噬纤维菌、中间普氏菌、变黑普氏菌数量、外周血Th17细胞占比、Th17/Treg比值、血清IL-17水平呈正相关（P＜0.05）,与外周血Treg细胞占比呈负相关（P＜0.05）。结论：慢性牙周炎伴T2DM患者龈沟液中miR-155、miR-233表达均上调,且与牙周组织破坏程度、龈下菌群紊乱和Th17/Treg失衡有关。     

不明原因复发性流产再次妊娠患者血清1,25(OH)2D3、sTim-3与Th17/Treg免疫失衡和妊娠结局的关系

摘要 目的：探讨不明原因复发性流产（URSA）再次妊娠患者血清1,25-二羟维生素D3[1,25（OH)）₂D₃]、可溶性T细胞免疫球蛋白黏蛋白分子3（sTim-3）与辅助性T细胞17（Th17）/调节性T细胞（Treg）免疫失衡和妊娠结局的关系。方法：选择于湖南省妇幼保健院2020年1月~2022年1月就诊的62例URSA再次妊娠患者作为研究组,另选择同期进行孕检的正常早孕妇女30例作为对照组。比较两组孕早期血清1,25(OH) ₂D₃、sTim-3及外周血Th17细胞、Treg细胞水平、Th17/Treg比值。Pearson法分析URSA再次妊娠患者血清1,25(OH) ₂D₃、sTim-3与外周血Th17细胞、Treg细胞水平、Th17/Treg比值平的相关性。根据URSA再次妊娠患者妊娠结局的不同分为妊娠成功分娩组和妊娠再次流产组,比较两组孕早期血清1,25(OH) ₂D₃、sTim-3与外周血Th17细胞、Treg细胞水平、Th17/Treg比值。受试者工作特征（ROC）曲线分析血清1,25(OH) ₂D₃、sTim-3与外周血Th17细胞、Treg细胞水平、Th17/Treg比值对妊娠结局的预测价值。结果：研究组血清sTim-3、外周血Th17细胞水平、Th17/Treg比值高于对照组,血清1,25(OH) ₂D₃、外周血Treg细胞水平低于对照组（P<0.05）。Pearson相关分析显示,URSA再次妊娠患者血清1,25(OH) ₂D₃与血清sTim-3、外周血Th17细胞水平、Th17/Treg比值呈负相关,与Treg细胞水平呈正相关（P<0.05）;血清sTim-3与外周血Treg细胞水平呈负相关,与Th17细胞水平、Th17/Treg比值呈正相关（P<0.05）。妊娠再次流产组血清sTim-3、外周血Th17细胞水平、Th17/Treg比值高于妊娠成功分娩组,血清1,25(OH) ₂D₃、外周血Treg细胞水平低于妊娠成功分娩组（P<0.05）。ROC曲线分析显示,血清1,25(OH) ₂D₃、sTim-3及外周血Th17细胞、Treg细胞水平及Th17/Treg比值均可预测URSA再次妊娠患者妊娠再次流产的发生风险,且上述指标联合检测的预测效能更高。结论：血清1,25(OH) ₂D₃水平异常降低、sTim-3水平异常升高可导致Th17/Treg免疫失衡,导致URSA再次妊娠患者再次发生流产。上述指标联合检测对URSA再次妊娠患者妊娠再次流产的预测效能更高。     

牙龈卟啉单胞菌感染对慢性牙周炎患者牙周指标、NLRP-3炎性小体通路和Th17/Treg细胞平衡的影响

摘要 目的：探讨牙龈卟啉单胞菌（PG）感染对慢性牙周炎（CP）患者牙周指标、Nod样受体蛋白-3（NLRP-3）炎性小体通路和辅助性T细胞17（Th17）/调节性T细胞（Treg）平衡的影响。方法：选择2018年6月至2021年11月在本院进行拔牙治疗的慢性牙周炎患者106例为CP组,根据是否感染PG分为感染组和未感染组;另选择因阻生齿、错位牙在本院进行治疗的牙周健康患者63例为对照组。记录所有对象的探诊深度（PD）、菌斑指数（PLI）、出血指数（BI）、附着丧失（AL）,采用聚合酶链式反应（PCR）技术检测PG感染率,采用RT-PCR技术检测牙周膜组织中NLRP-3 mRNA,接头蛋白凋亡相关斑点样蛋白（ASC） mRNA、半胱氨酸天冬氨酸酶-1（Caspase-1） mRNA的表达量,采用FACSCalibur流式细胞仪检测外周血Th17、Terg 水平并计算Th17/Treg,比较两组各检测指标水平。结果：对照组PG感染阳性率为17.46%,低于CP组的79.25%,两组比较差异有统计学意义（P＜0.05）。感染组PD、PLI、BI、AL水平均高于非感染组,差异有统计学意义（P＜0.05）。感染组NLRP-3 mRNA、ASC mRNA、Caspase-1 mRNA表达量均高于非感染组,差异有统计学意义（P＜0.05）。感染组外周血Th17细胞、Th17/Treg水平高于非感染组,Treg水平低于非感染组,差异有统计学意义（P＜0.05）。结论：CP患者多数存在PG感染,PG感染对患者的牙周健康、炎症及免疫有明显的影响。     

侵袭性牙周炎伴错牙合畸形患者牙周-正畸联合治疗前后血清SAA、leptin的变化及与牙周指标和辅助性T细胞亚群的相关性分析

摘要 目的：探讨侵袭性牙周炎伴错牙合畸形患者牙周-正畸联合治疗前后血清淀粉样蛋白A（SAA）、瘦素（leptin）的变化及与牙周指标和辅助性T细胞（Th）亚群的相关性。方法：选择2020年6月-2022年8月解放军总医院京中医疗区黄寺门诊部口腔科收治的80例侵袭性牙周炎伴错牙合畸形患者（牙周炎组）和65例于口腔门诊检查的健康志愿者（对照组）。所有患者均接受牙周-正畸联合治疗,治疗前后分别检测血清SAA、leptin水平以及外周血中Th1、Th2、Th17细胞占比,并评估牙周指标变化。Pearson相关性分析血清SAA、leptin水平与牙周指标以及外周血中Th1、Th2、Th17细胞占比的相关性。结果：牙周炎组治疗前血清SAA、leptin水平,外周血Th1、Th17细胞占比,出血指数（SBI）、菌斑指数（PLI）、附着丧失（AL）、牙周探诊深度（PD）高于对照组（P＜0.05）,外周血Th2细胞占比低于对照组（P＜0.05）。牙周炎组治疗后血清SAA、leptin水平,外周血Th1、Th17细胞占比,PLI、SBI、AL、PD较治疗前降低（P＜0.05）,外周血Th2细胞占比较治疗前增高（P＜0.05）。牙周炎组血清SAA、leptin与PLI、SBI、AL、PD,外周血Th1、Th17细胞占比呈正相关,与外周血Th2细胞占比呈负相关（P＜0.05）。结论：侵袭性牙周炎伴错牙合畸形患者血清SAA、leptin水平增高,经牙周-正畸联合治疗后下降,高水平SAA、leptin与牙周组织破坏程度以及Th亚群紊乱有关,检测血清SAA、leptin水平可评估侵袭性牙周炎牙周组织破坏程度以及细胞免疫状态。     

慢性牙周炎合并2型糖尿病患者龈沟液miR-21、miR-34a表达水平与牙周指标和Th1/Th2/Th17失衡的关系研究

摘要 目的：探讨慢性牙周炎（CP）合并2型糖尿病（T2DM）患者龈沟液微小核糖核酸（miR）-21、miR-34a表达水平与牙周指标和辅助性T细胞（Th）1/Th2/Th17失衡的关系。方法：选取2020年3月～2022年3月首都医科大学附属北京世纪坛医院口腔科收治的114例CP患者，根据是否合并T2DM分为CP合并T2DM组36例和单纯CP组78例，另选取60名健康体检者为对照组。对比三组牙周指标、龈沟液miR-21、miR-34a表达和外周血Th1、Th2、Th17、Th1/Th2/Th17、血清Th1、Th2、Th17相关细胞因子水平，采用Spearman相关性分析CP合并T2DM患者龈沟液miR-21、miR-34a表达与牙周指标和外周血Th1、Th2、Th17、Th1/Th2/Th17及其相关细胞因子水平的相关性。采用Pearson/Spearman相关性分析CP合并T2DM患者牙周指标与外周血Th1、Th2、Th17、Th1/Th2/Th17及其相关细胞因子水平的相关性。结果：对照组、单纯CP组、CP合并T2DM组菌斑指数（PLI）、牙龈出血指数（BI）、附着丧失（AL）、探诊深度（PD）依次增加，龈沟液miR-21和外周血Th2及血清白细胞介素（IL）-2、干扰素-γ（INF-γ）依次降低，龈沟液miR-34a和外周血Th1、Th17、Th1/Th2/Th17及血清IL-4、IL-10、IL-17、肿瘤坏死因子-α（TNF-α）依次升高（P＜0.05）。Spearman相关性分析显示，CP合并T2DM患者龈沟液miR-21表达与PLI、BI、AL、PD和外周血Th1、Th17、Th1/Th2/Th17及血清IL-4、IL-10、IL-17、TNF-α呈负相关，与外周血Th2和血清IL-2、INF-γ呈正相关（P＜0.05）；而miR-34a则与之相反。Pearson/Spearman相关性分析显示，CP合并T2DM患者PLI、BI、AL、PD与外周血Th1、Th17、Th1/Th2/Th17和血清IL-4、IL-10、IL-17、TNF-α呈正相关，与外周血Th2和血清IL-2、INF-γ呈负相关（P＜0.05）。结论：CP合并T2DM患者龈沟液miR-21低表达和miR-34a高表达，与牙周状况差有关，可能通过调节Th1/Th2/Th17失衡参与CP合并T2DM进展。     

术前修正衰弱指数联合血清PGE2、IL-17A预测老年髋关节置换术患者术后谵妄的临床研究

摘要 目的：探讨术前修正衰弱指数（mFI）联合血清前列腺素E₂（PGE₂）、白细胞介素-17A（IL-17A）预测老年髋关节置换术患者术后谵妄（POD）的临床研究。方法：选取2020年1月～2022年7月四川大学华西医院收治的276例老年髋关节置换术患者，根据是否发生POD分为POD组和非POD组。计算术前mFI，采用酶联免疫吸附法检测血清PGE₂、IL-17A水平。分析老年髋关节置换术患者POD的影响因素，采用受试者工作特征（ROC）曲线分析mFI和血清PGE₂、IL-17A水平对老年髋关节置换术患者POD的预测价值。结果：276例老年髋关节置换术患者POD发生率为17.03%（47/276）。与非POD组比较，POD组mFI和血清PGE₂、IL-17A水平升高（P＜0.05）。多因素Logistic回归分析显示，年龄、糖尿病、脑卒中、mFI、PGE₂、IL-17A为老年髋关节置换术患者POD的独立危险因素（P＜0.05）。ROC曲线分析显示，mFI联合血清PGE₂、IL-17A预测老年髋关节置换术患者POD的曲线下面积（AUC）大于mFI、PGE₂、IL-17A单独预测（P＜0.05）。结论：mFI和血清PGE₂、IL-17A水平升高与老年髋关节置换术患者POD独立相关，mFI联合血清PGE₂、IL-17A预测老年髋关节置换术患者POD的价值较高，可能成为老年髋关节置换术患者POD的辅助预测指标。     

血清HSP27、YKL-40与侵袭性牙周炎患者Th17、Treg细胞的关系及对牙周-正畸联合治疗后预后的影响分析

摘要 目的：分析血清热休克蛋白27（HSP27）、人软骨糖蛋白(YKL-40)与侵袭性牙周炎（AgP）患者辅助性T细胞17（Th17）、调节性T细胞（Treg）的关系及对牙周-正畸联合治疗后预后的影响。方法：选取2020年5月-2022年4月河北北方学院附属第一医院收治的98例AgP患者为AgP组,另选取同期于医院检查的60例牙周健康志愿者作为对照组。采用酶联免疫法检测血清HSP27、YKL-40水平,流式细胞仪检测外周血Th17、Treg百分比,计算Th17/Treg比值;Pearson法分析血清HSP27、YKL-40与Th17、Treg细胞的相关性。AgP患者经牙周-正畸联合治疗6个月后,复诊检查时根据牙周探针深度（PD）将患者纳入预后良好组（PD＜4 mm）和预后不良组（PD≥4 mm）。采用Logistic回归模型分析AgP患者牙周-正畸联合治疗后预后不良的影响因素。结果：AgP组血清HSP27水平低于对照组,YKL-40水平高于对照组（P＜0.05）。AgP组外周血中Th17细胞百分比、Th17/Treg比值高于对照组,Treg细胞百分比低于对照组（P＜0.05）。Pearson法显示,Th17细胞百分比、Th17/Treg比值与HSP27表达呈负相关,Treg细胞百分比与其呈正相关（P＜0.05）;Th17细胞百分比、Th17/Treg比值与YKL-40表达呈正相关,Treg细胞百分比与其呈负相关（P＜0.05）。复查结果显示,预后良好患者共61例,预后不良共37例。预后良好组与预后不良组在患牙上下、前后分布、根形态、患牙PD最深值、牙槽骨高度、菌斑指数及HSP27、YKL-40水平方面比较差异有统计学意义（P＜0.05）。Logistic回归显示,根形异常、患牙PD深、牙槽骨高度高、菌斑指数大、HSP27水平下降、YKL-40水平上升为AgP患者牙周-正畸联合治疗后预后不良的危险因素（P＜0.05）。结论：AgP患者血清HSP27水平下降、YKL-40水平上升,与Th17、Treg细胞表达密切相关,是影响患者牙周-正畸联合治疗后预后不良的危险因素。     

桥本甲状腺炎患者血清miR-326、miR-155与甲状腺相关抗体和Th17/Treg细胞因子失衡的相关性分析

摘要 目的：探讨桥本甲状腺炎（HT）患者血清微小核糖核酸（miR）-326、miR-155与甲状腺相关抗体和辅助性T细胞17（Th17）/调节性T细胞（Treg）细胞因子失衡的相关性。方法：选择2021年1月至2022年10月空军军医大学唐都医院收治的HT患者82例作为研究组，同期接受体检的健康人80例作为对照组，比较两组血清miR-326、miR-155、甲状腺功能参数[促甲状腺激素（TSH）、游离三碘甲状原氨酸（FT₃）、游离甲状腺素（FT₄）]、甲状腺相关抗体[甲状腺过氧化物酶抗体（TPOAb）、甲状腺球蛋白抗体（TGAb）]、Th17、Treg水平及其细胞因子水平，并分析HT患者血清miR-326、miR-155与甲状腺相关抗体和Th17/Treg细胞因子失衡的相关性。结果：研究组TSH、TPOAb、TGAb显著高于对照组，FT₃、FT₄显著低于对照组（P<0.05）。研究组血清miR-326、miR-155表达水平显著高于对照组（P<0.05）。研究组Th17、Th17/Treg、白细胞介素-17（IL-17）、γ干扰素（IFN-γ）显著高于对照组，Treg、白细胞介素-10（IL-10）水平显著低于对照组（P<0.05）。Pearson相关分析显示，HT患者血清miR-326、miR-155分别与TSH、TPOAb、TGAb、Th17、Th17/Treg、IL-17、IFN-γ呈正相关，与FT₃、FT₄、Treg、IL-10呈负相关（P<0.05）。结论：HT患者血清miR-326、miR-155水平异常升高，其水平与TPOAb、TGAb自身抗体及Th17/Treg失衡相关，血清miR-326、miR-155可能通过影响Th17/Treg免疫平衡，促进HT的发生和发展。     

Interaction of the Thermoplasma acidophilum A1A0-ATP synthase peripheral stalk with the catalytic domain

The peripheral stalk of the archaeal ATP synthase (A₁A₀)-ATP synthase is formed by the heterodimeric EH complex and is part of the stator domain, which counteracts the torque of rotational catalysis. Here we used nuclear magnetic resonance spectroscopy to probe the interaction of the C-terminal domain of the EH heterodimer (E_CT1H_CT) with the N-terminal 23 residues of the B subunit (B_NT). The data show a specific interaction of B_NT peptide with 26 residues of the E_CT1H_CT domain, thereby providing a molecular picture of how the peripheral stalk is anchored to the A₃B₃ catalytic domain in A₁A₀.

Structured summary

MINT-7260681: Hct (refseq:NP_393485), Ect1 (uniprotkb:Q9HM68) and Bnt (uniprotkb:Q9HM64) physically interact (MI:0915) by nuclear magnetic resonance (MI:0077)     

Heterogeneity of hemoglobin A1d: assessment and partial characterization of two new minor hemoglobins, A1d3a and A1d3b, increased in uremic and diabetic patients, respectively

We have separated and quantified two new minor hemoglobins named HbA_1d3a and HbA_1d3b. The level of HbA_1d3a was significantly higher in uremic than in non-uremic patients (3.00 ± 0.50% vs. 1.28 ± 0.26% of total hemoglobin). It correlated well with carbamylated hemoglobin (r=0.80, n=81, p<0.002) and with plasma urea concentration (r=0.78, n=81, p<0.002). These data and the electrospray ionization mass spectrometric analysis provide strong evidence that HbA_1d3a is an α-chain modified by carbamylation. The HbA_1d3b level in the diabetic patients was found to be 1.6-fold that in non-diabetic subjects (3.00 ± 0.49 vs. 1.90 ± 0.33). This was attributed to HbA_1d3 modified by glycation. Indeed HbA_1d3b correlated significantly with HbA_1c (r=0.71, p<0.002) and with serum glucose level (r=0.62, p<0.002). These two new minor hemoglobins may serve as complements for the objective assessment of averagd long-term uremia and glycemia in uremic and diabetic patients.     

Insights on the structure of native CNF,an endogenous phospholipase A2 inhibitor from Crotalus durissus terrificus, the South American rattlesnake

Several snake species possess endogenous phospholipase A₂ inhibitors (sbPLIs) in their blood plasma, the primary role of which is protection against an eventual presence of toxic phospholipase A₂ (PLA₂) from their venom glands in the circulation. These inhibitors have an oligomeric structure of, at least, three subunits and have been categorized into three classes (α, β and γ) based on their structural features. SbγPLIs have been further subdivided into two subclasses according to their hetero or homomeric nature, respectively. Despite the considerable number of sbγPLIs described, their structures and mechanisms of action are still not fully understood. In the present study, we focused on the native structure of CNF, a homomeric sbγPLI from Crotalus durissus terrificus, the South American rattlesnake. Based on the results of different biochemical and biophysical experiments, we concluded that, while the native inhibitor occurs as a mixture of oligomers, tetrameric arrangement appears to be the predominant quaternary structure. The inhibitory activity of CNF is most likely associated with this oligomeric conformation. In addition, we suggest that the CNF tetramer has a spherical shape and that tyrosinyl residues could play an important role in the oligomerization. The carbohydrate moiety, which is present in most sbγPLIs, is not essential for the inhibitory activity, oligomerization or complex formation of the CNF with the target PLA₂. A minor component, comprising no more than 16% of the sample, was identified in the CNF preparations. The amino-terminal sequence of that component is similar to the B subunits of the heteromeric sbγPLIs; however, the role played by such molecule in the functionality of the CNF, if any, remains to be determined.     

Nitrogen cycling in low input legume-based agriculture,with emphasis on legume/grass pastures

Low input legume-based agriculture exists in a continuum between subsistence farming and intensive arable and pastoral systems. This review covers this range, but with most emphasis on temperate legume/grass pastures under grazing by livestock. Key determinants of nitrogen (N) flows in grazed legume/grass pastures are: inputs of N from symbiotic N₂ fixation which are constrained through self-regulation via grass/legume interactions; large quantities of N cycling through grazing animals with localised return in excreta; low direct conversion of pasture N into produce (typically 5–20%) but with N recycling under intensive grazing the farm efficiency of product N: fixed N can be up to 50%; and regulation of N flows by mineralisation/immobilisation reactions. Pastoral systems reliant solely on fixed N are capable of moderate-high production with modest N losses e.g. average denitrification and leaching losses from grazed pastures of 6 and 23 kg N ha^–1 yr^–1. Methods for improving efficiency of N cycling in legume-based cropping and legume/grass pasture systems are discussed. In legume/arable rotations, the utilisation of fixed N by crops is influenced greatly by the timing of management practices for synchrony of N supply via mineralisation and crop N uptake. In legume/grass pastures, the spatial return of excreta and the uptake of excreta N by pastures can potentially be improved through dietary manipulation and management strategies. Plant species selection and plant constituent modification also offer the potential to increase N efficiency through greater conversion into animal produce, improved N uptake from soil and manipulation of mineralisation/immobilisation/nitrification reactions.     

Cobalt(III) complexes with linear hexadentate N6 or N4S2 donor set atoms providing pyridyl-amide-amine/thioether coordination

Two new cobalt(III) complexes of symmetric hexadentate ligand with N₆ [1,10-bis(2-picolinamide)-4,7-diazadecane (pycdpnen)] and N₄S₂ [1,8-bis(2-picolinamide)-3,6-dithiaoctane (pycdadt)] donor set atoms have been synthesized as perchlorate salts and characterized by spectroscopic methods. All two ligands with strong-field pyridylcarboxamido N donor stabilize Co(III) as demonstrated by the facile oxidation of the cobalt center. The structures of [Co(pycdpnenH₋₂)](ClO₄) (1) and [Co(pycdadtH₋₂)](ClO₄) · H₂O (2) investigated by COSY, HMBC, HMQC and NOESY NMR studies show that compounds 1 and 2 have the same geometrical configuration. The X-ray analysis reveals that complex 2 crystallizes in a orthorhombic space group Pccn. The cation [Co(pycdadtH₋₂)]⁺ is distorted octahedral with the two pyridyl groups in cis position.     

Crystal structure of leukotriene A4 hydrolase in complex with kelatorphan, implications for design of zinc metallopeptidase inhibitors

Leukotriene A₄ hydrolase (LTA4H) is a key enzyme in the inflammatory process of mammals. It is an epoxide hydrolase and an aminopeptidase of the M1 family of the MA clan of Zn-metallopeptidases. We have solved the crystal structure of LTA4H in complex with N-[3(R)-[(hydroxyamino)carbonyl]-2-benzyl-1-oxopropyl]-L-alanine, a potent inhibitor of several Zn-metalloenzymes, both endopeptidases and aminopeptidases. The inhibitor binds along the sequence signature for M1 aminopeptidases, GXMEN. It exhibits bidentate chelation of the catalytic zinc and binds to LTA4H’s enzymatically essential carboxylate recognition site. The structure gives clues to the binding of this inhibitor to related enzymes and thereby identifies residues of their S1′ sub sites as well as strategies for design of inhibitors.     

早产儿急性呼吸窘迫综合征血清1,25-(OH)2D3、PGRN、SIRT1、CTRP3水平与炎症反应和预后的关系研究

摘要 目的：探讨不同病情严重程度早产儿急性呼吸窘迫综合征（ARDS）血清1,25-二羟维生素D₃（1,25-(OH) ₂D₃）、颗粒体蛋白前体（PGRN）、沉默信息调节因子2相关酶1（SIRT1）、C1q/肿瘤坏死因子相关蛋白3（CTRP3）的变化，分析其与炎症反应和预后的关系。方法：选择2018年10月至2019年12月安徽省妇幼保健院收治的ARDS早产儿100例作为ARDS组，另选取同期在我院出生的健康新生儿60例作为对照组。根据《"新生儿急性呼吸窘迫综合征"蒙特勒标准（2017年版）》的病情判定标准将ARDS早产儿分为轻度组（n=40）、中度组（n=32）、重度组（n=28），比较不同病情严重程度ARDS早产儿血清1,25-(OH) ₂D₃、PGRN、SIRT1、CTRP3、炎症反应指标肿瘤坏死子因子-α（TNF-α）、白细胞介素-6（IL-6）、白细胞介素-1β（IL-1β）水平变化，采用Pearson法分析ARDS早产儿血清1,25-(OH) ₂D₃、PGRN、SIRT1、CTRP3与炎症反应指标的相关性。另根据ARDS组患儿预后情况分为预后良好组（n=65）和预后不良组（n=35），采用单因素和多因素Logistic回归分析影响ARDS早产儿预后不良的危险因素。结果：ARDS组血清1,25-(OH) ₂D₃、SIRT1、CTRP3、PGRN水平明显低于对照组（P<0.05），ARDS组血清TNF-α、IL-6、IL-1β水平明显高于对照组（P<0.05）。不同病情严重程度ARDS早产儿血清1,25-(OH) ₂D₃、PGRN、SIRT1、CTRP3、炎症反应指标比较差异有统计学意义（P<0.05）。ARDS早产儿血清1,25-(OH) ₂D₃、PGRN、SIRT1、CTRP3水平与TNF-α、IL-6、IL-1β水平呈负相关（P<0.05）。多因素Logistic回归分析结果显示，低出生体重、肺表面活性物质（PS）使用次数≥3次、出现低白蛋白血症是影响ARDS早产儿预后不良的危险因素（P<0.05），血清1,25-(OH)2D3（较高）、PGRN（较高）、SIRT1（较高）、CTRP3（较高）是ARDS早产儿预后不良的保护因素（P<0.05）。结论：血清1,25-(OH) ₂D₃、PGRN、SIRT1、CTRP3可能参与ARDS早产儿的炎症反应过程，与ARDS早产儿的病情进展及预后密切相关，检测血清1,25-(OH) ₂D₃、PGRN、SIRT1、CTRP3有助于评估ARDS早产儿的预后。     

Study on the heterogeneous degradation of chitosan with H2O2 catalyzed by a new supermolecular assembly crystal: [C6H8N2]6H3[PW12O40]·2H2O

A new supermolecular assembly crystal, [C₆H₈N₂]₆H₃[PW₁₂O₄₀]·2H₂O (DMB-PWA), was synthesized with phosphotungstic acid (PWA) and 1,2-diaminobenzene (DMB) under hydrothermal conditions and was characterized by Fourier-transform infrared spectra (FTIR) and single-crystal X-ray diffraction analysis. DMB-PWA could effectively catalyze oxidative degradation of chitosan with H₂O₂ in the heterogeneous phase. The optimum degradation conditions were determined by orthogonal tests as follows: amount of chitosan 1.00 g, 30% (wt %); H₂O₂, 3.0 mL; dosage of catalyst, 0.06 g; reaction temperature, 85 °C; and reaction time, 30 min. The water-soluble chitosan with a viscosity-average molecular weight (M_v) of 4900 was obtained under the optimum degradation conditions and was characterized by FTIR, ultraviolet-visible diffuse reflection spectra (UV-vis DRS), and X-ray powder diffraction analysis.