Responsiveness of G protein-coupled odorant receptors is partially attributed to the activation mechanism

Mammals detect and discriminate numerous odors via a large family of G protein-coupled odorant receptors (ORs). However, little is known about the molecular and structural basis underlying OR response properties. Using site-directed mutagenesis and computational modeling, we studied ORs sharing high sequence homology but with different response properties. When tested in heterologous cells by diverse odorants, MOR256-3 responded broadly to many odorants, whereas MOR256-8 responded weakly to a few odorants. Out of 36 mutant MOR256-3 ORs, the majority altered the responses to different odorants in a similar manner and the overall response of an OR was positively correlated with its basal activity, an indication of ligand-independent receptor activation. Strikingly, a single mutation in MOR256-8 was sufficient to confer both high basal activity and broad responsiveness to this receptor. These results suggest that broad responsiveness of an OR is at least partially attributed to its activation likelihood.G protein-coupled receptors (GPCRs) are seven transmembrane (TM) proteins which play essential roles in converting extracellular stimuli into intracellular signals in a variety of cell types. Odor detection by olfactory sensory neurons (OSNs) in the mammalian nose depends on a large family of G protein-coupled odorant receptors (ORs) (1), which endows the olfactory system with an extraordinary power of odor detection and discrimination. Although OR-ligand binding is the first step toward smell perception, little is known about the molecular and structural basis underlying odor response properties of individual ORs.Most mammalian ORs respond to a small fraction of all of the tested odorants (2). In contrast, recent studies have identified a small number of ORs that respond to a large set of diverse odorants with comparable potency and efficacy as the former. Curiously, several broadly responsive ORs including MOR256-3 (Olfr124 or SR1), MOR256-31 (Olfr263), and human OR2W1 (ortholog of MOR256-31) belong to the same subfamily, which also contains ORs such as MOR256-8 (Olfr1362) and MOR256-22 (Olfr1387) that respond to a few odorants (3–6). Identification of ORs within the same subfamily (i.e., sharing >50% amino acid identity) but with different response properties offers an opportunity for dissecting out the molecular features that define the tuning properties of these ORs.Mammalian ORs belong to class A (or rhodopsin family) GPCRs. The structure-function relationship of several class A members (e.g., rhodopsin and β2-adrenergic receptor) has been investigated in great details via various approaches including site-directed mutagenesis, X-ray crystallography (7, 8), and molecular modeling (9–11). Although no crystal structure is available for any OR, site-directed mutagenesis and/or computational modeling have shed light on structure-function relationship for a few ORs (12–18).Using a joint approach of site-directed mutagenesis and computational modeling, we investigated the response properties of mutant ORs based on MOR256-3 and MOR256-8, which responded to a large and small set of odorants, respectively. Three-dimensional atomic models of these ORs were built to map locations of the mutated residues. Most mutations in MOR256-3 altered the responses to different odorants in a similar manner. Remarkably, MOR256-8 was converted into a broadly responsive OR by swapping a single or a few residues. More generally, we found that an OR’s total response was positively correlated with its basal activity, an indication of ligand-independent receptor activation. These data suggest that broad responsiveness of an OR is not only determined by ligand binding, but also by activation mechanism.     

Maternal emotional availability at bedtime and infant cortisol at 1 and 3 months

Background

Previous work has shown that early experience influences infant cortisol secretion. Few studies, however, have examined associations between parenting quality and cortisol levels and patterning in very young infants.

Aims

This study examined linkages between maternal emotional availability (EA) during a routine caregiving task, bedtime, and infant cortisol in the first 3 months of life. Concurrent and longitudinal associations between maternal EA and infant cortisol were examined.

Study design

Families were visited when their infants were 1 and 3 months old. Video equipment was set up in order to record the infant's bedtime routine. Parents were provided with materials with which to take saliva samples from their infants at late afternoon, bedtime, and the following morning.

Subjects

At 1 month, participants were 96 mothers and infants living in a rural U.S. state. Data were available for 88 mothers and infants at 3 months.

Outcome measures

Maternal EA was scored from videotapes of bedtime at each age point. Infant cortisol was assessed from the saliva samples taken by parents.

Results

Regression analyses indicated that at 1 and 3 months of age, infants of more emotionally available mothers showed lower levels of cortisol secretion across the night than infants of less emotionally available mothers. Additionally, multilevel model analyses indicated that infants of more emotionally available mothers showed greater evidence of a decline in their cortisol levels across the evening, followed by an increase across the nighttime into the morning in their cortisol at 3 months.

Conclusions

Findings suggest that maternal care in the context of a routine caregiving task is associated with lower stress reactivity and with earlier circadian patterning in very young infants.     

白背叶HPLC特征指纹图谱及模式识别

目的:建立白背叶药材的HPLC指纹图谱与系统聚类分析方法,为科学评价和有效控制白背叶药材的质量提供科学依据。方法:采用高效液相色谱法建立12个不同产地白背叶的指纹图谱,采用phenomenex-C18色谱柱(4.6 mm×250 mm,5μm);以甲醇-0.1%冰乙酸水为流动相,梯度洗脱,流速1.0 m L·min-1,柱温25℃,检测波长336 nm。并使用相似度评价软件进行相似度分析,用SPSS 19.0软件进行聚类分析,以共有峰的相对峰面积为指标,进行标准化处理和主成分分析。结果:建立了白背叶HPLC指纹图谱共有模式,对不同产地白背叶药材进行了相似度比较,并进行了指纹图谱系统聚类分析和主成分分析。标定了22个共有峰,指认了其中5个共有峰,经相似度计算,整体相似度为0.554~0.981。聚类分析在距离标尺为2时将样品2,3,4,5,6,8,9,10,12分为一大类;综合主成分得分(F值)从高到低依次为11,7,1,9,12,6,5,10,4,3,2,8号样品,F在0.0~-1.7共2种方法的分类结果一致,可以相互验证。结论:该方法简便准确、灵敏度高、重复性好,为白背叶药材的研究以及制定质量控制标准提供科学依据。     

The up-regulation of heme oxygenase-1 expression in human gingival fibroblasts stimulated with nicotine

BACKGROUND: Cigarette smoking is a major risk factor in the development and further progression of periodontal diseases. Heme oxygenase-1 (HO-1) is known as a stress-inducible protein and functions as an antioxidant enzyme. There is limited information on the expression of HO-1 in smoking-associated periodontal disease. OBJECTIVES: The aim of the present study was to investigate the effects of nicotine on the expression of HO-1 protein in cultured human gingival fibroblasts in vitro and further to compare HO-1 expression in gingival tissues obtained from cigarette smokers and non-smokers in vivo. METHODS: Western blot assay was used to investigate the effects on human gingival fibroblasts exposed to nicotine. In addition, antioxidants catalase, superoxide dismutase (SOD), and N-acetyl-l-cysteine (NAC) were added to test how they modulated the effects on nicotine-induced HO-1 expression. Gingival biopsies taken from the flap surgery of 20 male patients with periodontal disease (10 cigarette smokers and 10 non-smokers) were examined by immunohistochemistry. RESULTS: The exposure of quiescent human gingival fibroblasts to 10 mm nicotine resulted in the induction of HO-1 protein expression in a time-dependent manner (p < 0.05). The addition of glutathione (GSH) precursor NAC inhibited the nicotine-induced HO-1 protein expression (p < 0.05). However, SOD and catalase did not decrease the nicotine-induced HO-1 protein expression (p > 0.05). The results from immunohistochemistry demonstrated that HO-1 expression was significantly higher in cigarette smokers (p < 0.05). HO-1 was noted in the basal layers of epithelium, inflammatory cells, and fibroblasts in specimens from cigarette smoking. CONCLUSIONS: Taken together, these results suggest that HO-1 expression is significantly up-regulated in gingival tissues from cigarette smokers, and nicotine may, among other constituents, be responsible for the enhanced HO-1 expression in vivo. The regulation of HO-1 expression induced by nicotine is critically dependent on the intracellular GSH concentration.     

长春市某小学7～12岁儿童福赛斯坦氏菌和中间普氏菌分布状态调查

目的 应用聚合酶链反应(PCR)法对儿童口腔内福赛斯坦氏菌(Tannerella forsythus,Tf)和中间普氏菌(Prevotella intermedia,Pi)进行检测,探讨检出结果与牙周临床指标之间的关系.方法 选取长春市自强小学151名7至12岁儿童为研究对象,选择右上颌中切牙和第一磨牙为被检牙位,取龈上菌斑、记录探诊出血(bleeding on probing,BOP)、探诊深度(probing depth,PD)、牙龈指数(gingival index,GI),应用PCR法对儿童龈上菌斑中的Tf和Pi进行检测.结果 儿童龈上菌斑中Tf、Pi的检出率分别为40.3%(1 18/293)、46.4%(136/293);6颊面Tf、Pi的检出率分别为55.2%(80/145)、53.8%(78/145)均显著高于(1)唇面的Tf和Pi的检出率[分别为25.7%(38/148)、39.2%(58/148)],差异有统计学意义(P＜0.01);Pi检出率随年龄增长呈逐渐减低趋势,Tf检出率在7～8岁组最高,其次为11～12岁和9～10岁组;BOP阳性部位的Tf、Pi检出率[分别为43%(35/81)、49%(40/81)]均高于BOP阴性部位二者的检出率[分别为37%(72/194)、45%(87/194)].在BOP阳性部位,随PD加深Tf检出率逐渐增高,特别是在PD 4 mm以上时Tf检出率明显增高(P＜0.01),Tf检出率与BOP阳性、PD增加呈正相关.结论 7～12岁儿童龈上菌斑中高频度分布着Tf和Pi;上颌前牙区与磨牙区菌丛构成不同,Tf、Pi在磨牙区检出率更高,Tf的检出率与PD呈正相关,Tf检出率在7～8岁组最高,Pi检出率随年龄增长呈减低趋势,儿童时期进行牙周病早期预防是非常必要的.

Abstract：

Objective To detect the presence of Tannerella forsythus(Tf)and Prevotella intermedia (Pi) using polymerase chain reaction(PCR) in the oral plaque samples from children and investigate the relationship between bacteria and clinical parameters. Methods A total of 151 children aged 7 to 12 years were selected from Changchun primary school. The supragingival plaque sample was collected from the mesiobuccal and labial surfaces of the right maxillary central incisor ( FDI 1 ) and the right maxillary first molar ( FDI 6 ). Extracted DNA from plaque samples was used for PCR analysis. Intraoral examination,probing depth (PD) and bleeding on probing (BOP) were performed and recorded. Results The detection rate for Tf was 40. 3% ( 118/293 ) and Pi was 46. 4% ( 136/293 ) in supragingival plaque. The detection rates for Tf and Pi in molars were much higher than those in incisors( P ＜0. 01 ). The detection rate of Tf and Pi was positively related to BOP + and PD. The detection rate for Pi decreased gradually with age, and the detection rate for Tf was highest in the group aged 7 to 8 and the detection rates for Tf and Pi were higher in the gingiva with BOP + than that with BOP - ( P ＞ 0. 05 ). The detection rates for Tf increased remarkably with BOP + and especially when PD was greater than 4 mm. Conclusions Detection rates of putative periodontal pathogens from healthy children of 7 to 12 years of age were high. The detection rates for Tf and Pi in molars were much higher than those in incisors, and the presence of Tf and Pi in supragingival plaque was related to periodontal parameters.     

细菌胞外膜泡的电镜观察

本实验对分离的５株细菌的ＥＣＶ作了电镜观察，证实４株菌都能形成ＥＣＶ，但在量上有差异。以ＰｇＷ５０最为典型，菌体及其ＥＣＶ的结构层次清晰可见；ＰｅＥＣＶ的荚膜层较薄且直径相对小而均一；Ｐｍ和Ｐｉ的ＥＣＶ大小不均一，标本中破裂现象和不规碎片出现较早。     

3种口腔厌氧菌荚膜高效液相色谱特性比较

目的：比较３种口腔厌氧菌荚膜的高效液相色谱特性。方法：采用高效液相色谱技术。结果：凝胶色谱显示，牙龈卟啉菌荚膜为２个蛋白主峰，牙髓卟啉菌、中间型普里沃氏菌荚膜均为３个蛋白主峰；离子交换色谱显示，３种荚膜的活性部分均有一蛋白主峰和若干个小蛋白峰，主峰由蛋白和多糖构成，其比值分别为８．９：１，９．０：１，６．５：１。结论：３种荚膜的高效液相色谱特性基本相似。     

少汗型外胚层发育不全1例

本文报道1例外胚层发育不全病例,并分析外胚层发育不全的临床表现、发病原因及遗传方面的影响因素等.     

不同辅助治疗方式对术后存在中危因素宫颈癌患者的疗效及生活质量分析

目的:比较单纯化疗或同步放化疗辅助治疗宫颈癌(ⅠB1～ⅡA2)术后存在中危因素患者的临床疗效及远期毒副反应,并进行生活质量评估,探讨该类患者术后采用单纯化疗的可行性.方法:回顾性分析2016年2月至2018年4月就诊于安徽省肿瘤医院妇瘤科术后宫颈癌存在中危因素的患者.入组患者均行标准宫颈癌手术,术后根据辅助治疗途径分为化疗组和同步放化疗组,通过治疗的有效性、远期毒副反应及生存质量等指标探讨2种辅助治疗方式的临床疗效及安全性.结果:2组间的复发率(x2=0.288,P=0.591)和病死率(x2=0.238,P=0.625)比较差异均无统计学意义;化疗组的3年无进展生存率(87.70％)和3年总生存率(97.60％)高于同步放化疗组(分别为81.40％和89.70％),差异均无统计学意义(x2=0.787,P=0.375;x2=1.441,P=0.230);化疗组(16.70％)淋巴水肿的发生率低于放化疗组(37.21％),差异有统计学意义(x2=4.543,P=0.033);化疗组的生活质量得分(88.28±5.84)高于放化疗组(78.60±8.32),差异有统计学意义(t=6.020,P＜0.001).结论:单纯化疗辅助治疗ⅠB1～ⅡA2期宫颈癌根治术后具有中危因素的患者,也能获得较好的临床效果,并且毒副反应略轻于放化疗组,可以作为一种备选的辅助治疗方式供临床选择.     

医护人员血源性传播疾病职业暴露的现况分析

目的 探讨医护人员血源性传播疾病职业暴露的特征及危险因素,为其预防和干预提供有效依据.方法 回顾性分析海军军医大学(第二军医大学)长海医院2006年4月至2021年1月登记上报的746例医护人员血源性传播疾病职业暴露案例的资料,包括性别、年龄、职业、工作科室、职业暴露发生时间、暴露源、暴露途径、处理措施等.结果 从性别上看,发生血源性传播疾病职业暴露的女性(540例,72.39％)较男性(206例,27.61％)多;从职业来看,发生血源性传播疾病职业暴露的人员以护士(师)(305例,40.88％)、医师(171例,22.92％)和实习护士(111例,14.88％)为主;从科室分布看,发生血源性传播疾病职业暴露的医护人员所在科室主要为急诊科(105例,14.08％)、普通外科(73例,9.79％)、麻醉科(67例,8.98％)、消化科(55例,7.37％)、胸心外科(54例,7.24％).暴露源以HBV为主,共有508例(68.10％);暴露途径以皮肤锐器伤为主,共有666例(89.28％).36例(4.83％)发生暴露后未进行任何紧急处理,但所有暴露者均接受了后续的预防性治疗及随访,且最终无一例发生职业暴露感染.结论 医护人员血源性传播疾病职业暴露不容忽视,应增强对血源性传播疾病的防范意识、强化职业防护培训、建立合理有效的防护制度、改善诊疗环境,以降低血源性传播疾病的发生率、保证医护人员的身心健康.