尼古丁对牙周炎大鼠牙周膜成纤维细胞的毒性作用

目的:观察尼古丁对牙周炎大鼠牙周膜成纤维细胞(PDLFs)增殖的抑制作用及对细胞周期分布的影响,探讨尼古丁的细胞毒性作用,为口腔疾病的预防及治疗提供基础。方法:选取30只SD大鼠,采用丝线结扎联合口内接种细菌的方法建立牙周炎大鼠模型。将不同浓度的尼古丁分别作用于大鼠的牙周膜成纤维细胞(PDLFs)中,观察大鼠牙周组织的变化情况,MTT法测定细胞增殖活性,分析不同浓度尼古丁对PDLFs增殖的抑制作用。结果:实验组大鼠牙周组织胶原纤维束排列紊乱,有炎症细胞浸润;对照组大鼠牙龈未见红肿或出血。尼古丁可抑制PDLFs增殖,并且呈浓度依赖性,随着浓度的增加,对PDLFs增殖的抑制作用增强,差异具统计学意义(P0.05)。与对照组相比,不同浓度尼古丁作用下牙周炎大鼠牙周膜成纤维细胞周期的分布率明显不同(P0.05)。结论:尼古丁对牙周膜成纤维细胞增殖具有明显的抑制作用,尼古丁的浓度影响牙周组织的修复重构能力。     

慢性牙周炎与原发性肝硬化的相关性分析

目的:探究慢性牙周炎与原发性肝硬化之间的相关性。方法:选择2017年1月至2019年1月于我院接受治疗的60例原发性肝硬化患者为研究组,选择同期于我院接受体格检查的100例健康个体为对照组,对两组患者分别实施牙周检查,对比两组患者牙周炎发生率,分析吸烟、饮酒对牙周炎发生率影响,按照Child-改良分级法对肝硬化患者进行评分并分级,对比各级原发性肝硬化患者慢性牙周亚发生率,并就慢性牙周炎与肝硬化相关性进行分析。结果:(1)对照组慢性牙周炎发生率显著低于研究组慢性牙周炎发病率(44.00%vs. 71.67%,P0.05);(2)研究组和对照组中吸烟者的慢性牙周炎患病率显著高于不吸烟者(P0.05),研究组中吸烟者发生慢性牙周炎患病率高于对照组,对比无统计学意义(P0.05);研究组和对照组饮酒者的慢性牙周炎患病率显著高于不饮酒者(P0.05),研究组中饮酒者发生慢性牙周炎患病率显著高于对照组(P0.05);(3)随着原发性肝硬化患者评分的升高,患者牙周炎患病率也随之上升,牙周附着丧失程度也出现加剧(P0.05)。结论:原发性肝硬化患者慢性牙周炎患病率高于健康个体,随着肝硬化患者病情的加剧,患者慢性牙周炎发生率也随之上升;另外,吸烟及饮酒会增加健康个体慢性牙周炎患病率。     

烟草烟雾毒性的梨形四膜虫检测方法

吸烟不仅危害吸烟者本身的健康,而且能够通过被污染的空气,造成对不吸烟的被动吸烟者的健康危害,引起吸烟公害.烟草燃烧时所产生的烟雾中,大约含有1200余种有害成份,其中包括尼古丁等生物碱、胺类、腈类、醇类、酚类、烷烃、烯烃、醛类、氮氧化合物、多环芳烃、杂环族化合物、羰基化合物、重金属元素及有机农药等.这些有害成份对细胞生物具有多种有害物质毒性的联合作用.     

尼古丁调控细胞凋亡的分子机制

尼古丁是烟草中生物碱的主要成分,其生物学作用广泛。尼古丁参与影响神经系统、呼吸系统和心血管系统等重要器官的发育,并与癌症的发生有着密切的关系。尼古丁通过对细胞凋亡的调控,发挥其生物学作用。现对尼古丁调控细胞凋亡相关的各种信号通路及其分子机制进行综述。     

科研快讯

<正>《瘾生物学》:重度吸烟者伴有大脑结构与功能异常继此前的青少年网瘾神经影像研究引起国际广泛关注后,中科院武汉物理与数学研究所磁共振影像团队近期在吸烟(尼古丁)成瘾的脑成像研究方面又取得重要进展。相关成果在线发表于《瘾生物学》杂志。吸烟是导致包括肺癌在内的许多疾病的重要因素,也是全球普遍关注的公共卫生问题。近年来,越来越多的研究显示,吸烟不仅对呼吸系统、心血管系统产生负面影响,同时危害中枢神经系统。流行病学调查显示,相较于不吸烟者,长期重度吸烟者的神经认知功能有所下降。最近,中科院武汉物数所科研人员与武汉大学中南医院放射科合作,利用磁共振成像研究了平均年龄在50岁左右的重度吸烟者的大脑结构与功能异常。这     

牙龈卟啉单胞菌外膜囊泡与阿尔茨海默病的相关性研究进展

牙龈卟啉单胞菌(Porphyromonas gingivalis)是牙周炎的主要致病菌,在其生长过程中可产生大量毒力因子。P. gingivalis及其毒力因子不仅可引发牙周组织的破坏,还可扩散至全身并影响包括阿尔茨海默病(Alzheimer’s disease, AD)在内的多种系统疾病的发生、发展。P. gingivalis外膜囊泡包含亲本细菌的大量毒力因子且体积小,更易扩散至远处组织和器官。近期研究发现,P.gingivalis外膜囊泡可能在诱发神经炎症和促进AD的发生、发展中起重要作用,但具体机制尚不清楚。本文就P. gingivalis外膜囊泡的发生与调控、所含主要毒力因子及其与AD的关系进行综述,以阐明牙周炎与AD相关的生物学机制。     

尼古丁影响胃粘膜血流量和胃酸分泌

在临床上经常观察到,吸烟者胃及十二指肠溃疡的发病率要比不吸烟者高得多,同时,其消化性溃疡的愈合率也低。这是否与上消化道粘膜血流量减少、粘膜的完整性受到破坏的因素有关?最近,德国Sonnenberg等分别通过静脉内滴注尼古丁(nicotine)和直接吸烟,观察对胃粘膜血流量和胃酸分泌的影响。实验在八名不吸烟的和五名吸烟的、无上消化道病史的成年健康男性身上进行。实验前一天晚上禁食。整个实验时间为四小时,在前两小时,由静脉滴注五肽胃泌素;在后两个小时,(1)将不吸烟者分成四组,由静脉同时滴注五肽胃泌素和不同剂量(2.5、5、7.5、10μg/kg/hr)尼古丁;(2)给五名吸烟者各吸入香烟5支(每支含尼古丁0.4mg)。在实验开始时,受试者静脉内给予一定量中性红,然后按规定时间抽血,测定胃中性红清除率,作为反映胃粘膜血流量的指标,同时,通过胃管抽取胃液测定胃液量、胃酸排出量以及R值(即胃中性红清除率和胃分泌量的比率)。在实验的第二小时,上述各项指标均达到稳定状态,作为正常值。此时,胃液量为80ml/15min、胃酸分泌量为7.5mMol/15min,中性红清除率为74ml/min左右,R值为14。当静脉滴注不同剂量尼古丁后,胃液量、胃酸排出量、中性红清除率均降低,尤以前两者所受的抑制作用更为明显,R值升高,而且     

尼古丁预防帕金森氏综合症和老年痴呆症的分子机理研究

吸烟有害健康,吸烟产生的自由基、亚硝胺和多环芳烃等是主要有害物质,而尼古丁是造成吸烟依赖的主要物质。流行病学统计显示,吸烟者患帕金森氏综合症(Parkinson's disease,PD)和老年痴呆症(Alzheimer's disease,AD)的概率远低于不吸烟者;实验和人群结果表明尼古丁可以预防PD和AD,但其机理还不十分清楚。实验发现:1)尼古丁可以有效清除活性氧自由基,能够抑制多巴胺自氧化,是一种抗氧化剂;2)尼古丁能够有效抑制6-OHDA和MPP 诱导的细胞色素C(Cytochrome C,Cyt.C)释放;3)尼古丁可以保护海马神经元抵抗β淀粉样蛋白诱导的凋亡;4)尼古丁可以防止淀粉样蛋白在转基因AD鼠脑中的沉淀;5)尼古丁可以络合金属铜和锌,防止其在脑中积聚;6)尼古丁可以通过激活烟碱型乙酰胆碱受体nAChRs(nicotin acetylcholine receptor)7和MAPK(mitogen activated protein kinase)来抑制NF-κB和C-Myc信号通路,抑制炎症和诱导型NOS表达和NO生成,预防AD。这些结果对于解释尼古丁防治神经退行性疾病AD和PD的机理具有重要意义。     

吸烟与姐妹染色单体交换

用荧光加Giemsa(FPG)术区分姐妹染色单体,分析了13名中年男子外周血淋巴细胞的SCE,比较吸烟者和不吸烟者“自发”的和用丝裂霉素(MMC)诱发的SCE频率变化。发现吸烟者的SCE频率(8.33±1.08)显著地高于不吸烟者(4.41±0.72),p<0.001。用MMC诱发后吸烟者各剂量的SCE值也明显地高于不吸烟者(P<0.01),并随着MMC剂量的增加,两者之间的差值增大。由于SCE的形成同DNA损伤后的修复机制有关,SCE频率的不同反映交换产生过程中机体重组修复系统的差异。因此,吸烟者与不吸烟者SCE频率的差异,表明两者在DNA修复机制上存在着差异。吸烟很可能改变了机体DNA损伤后的修复能力。     

牙周炎易感基因的研究进展

牙周病是口腔常见病之一,牙周炎是指发生在牙齿支持组织的炎症。全国第二次流行病学调查结果显示：35～44岁年龄段的牙周炎患病率为97．2%,患病率居龋齿病之上,因此,预防和治疗牙周疾病将是长期艰巨的任务。目前,人们公认牙周微生物是牙周病的始动因子,但单有微生物并不意味着牙周病,尤其是牙周炎的必然发生。牙周炎是一类多因素疾病,目前比较明确的危险因素有：口腔卫生状况,吸烟与否,某些全身疾病如关节炎、心血管疾病和糖尿病等。近年来的研究表明,宿主的易感性在疾病的发生和进展中起至关重要的作用,早发性牙周炎和（或）重度牙周炎患者往往具有家族聚集性。一些学者对外部环境相同的人群进行多年的纵向观察,发现不同个体罹患牙周炎的几率不同,这种差别可能缘于基因背景不同。目前,从分子水平上揭示牙周炎的易感因素已成为21世纪牙周病学研究的新热点。     

Nicotine Deteriorates the Osteogenic Differentiation of Periodontal Ligament Stem Cells through α7 Nicotinic Acetylcholine Receptor Regulating wnt Pathway

Aims

Cigarette smoking is one of the high risk factors of adult chronic periodontitis and nicotine is the well established toxic substance in cigarette. However, the mechanism of nicotine induced periodontitis is still unknown. Here we studied whether nicotine impaired the osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs) through activating α7 nicotinic acetylcholine receptor (α7 nAChR).

Methods

hPDLSCs with multi differentiation potential and surface makers for mesenchymal stem cells were harvested by limiting dilution technique. The level of mineralized nodule formation was assessed by alizarin red S staining. Expression level of ostegenic related genes and proteins were detected by real-time PCR and western blot analysis. The expression of α7 nAChR and its downstream signaling pathway were examined by western blot. The role of the receptor and related signaling pathway in nicotine impairing the osteogenic potential of hPDLSCs were also studied in different levels.

Results

Nicotine deteriorated the ostegenic differentiation of hPDLSCs in a dose dependent manner. Activation of α7 nAChR by nicotine treatment activated wnt/β-catenin signaling pathway, leading to osteogenic deficiency of hPDLSCs. Blockage of α7 nAChR and wnt pathway inhibitor treatment rescued nicotine induced osteogenic differentiation deficiency.

Conclusions

These data suggested that nicotine activated α7 nAChR expressed on PDLSCs and further activated wnt signaling downstream, thus deteriorating the osteogenic potential of PDLSCs. The impairment of osteogenic differentiation of PDLSCs by nicotine might lead to cigarette smoking related periodontitis.     

Inflammation has synergistic effect with nicotine in periodontitis by up‐regulating the expression of α7 nAChR via phosphorylated GSK‐3β

Periodontitis is the leading cause of adult tooth loss, and those who smoke are at an increased risk of developing periodontitis. α7 nicotinic acetylcholine receptor (α7 nAChR) is proposed to mediate the potential synergistic effect of nicotine and inflammation in smoking‐related periodontitis. However, this has not been experimentally demonstrated. We isolated and cultured human periodontal ligament stem cells (PDLSCs) from healthy and inflamed tissues. PDLSCs were treated with either inflammatory factors or nicotine. We measured expression of genes that are associated with osteogenic differentiation and osteoclast formation using RT‐qPCR and Western blot analyses. Besides, immunohistochemical staining, micro‐CT analysis and tartaric acid phosphatase staining were used to measure α7 nAChR expression and function. Inflammation up‐regulated α7 nAChR expression in both periodontal ligament tissues and PDLSCs. The up‐regulated α7 nAChR contributed to the synergistic effect of nicotine and inflammation, leading to a decreased capability of osteogenic differentiation and increased capability of osteoclast formation‐induction of PDLSCs. Moreover, the inflammation‐induced up‐regulation of α7 nAChR was partially dependent on the level of phosphorylated GSK‐3β. This study provides experimental evidence for the pathological development of smoking‐related periodontitis and sheds new light on developing inflammation and α7 nAChR‐targeted therapeutics to treat and prevent the disease.     

Subgingival microflora in smokers with early onset periodontitis

Cigarette smoking is a potent risk factor which has recently been associated with periodontal disease progression. The objective of this study was to detect the microbial profile of early onset periodontitis in smokers and compare it to that of non-smokers. The study population consisted of 50 systemically healthy individuals aged 25 to 38 years, exhibiting early onset periodontitis. 25 patients were smokers (> 20 cigarettes/day) and 25 non-smokers. Two pooled bacterial samples comprised of four periodontal sites with probing depth > 5 mm each, were collected from each individual. The samples were cultured aerobically and anaerobically for bacterial isolation using selective and non-selective media. Isolates were characterized to species level by conventional biochemical tests and various identification kits. The differences in bacterial counts using the Mann Whitney U test were statistically significant for Staphylococcus aureus, Campylobacter concisus, Eikenella corrodens, Escherichia coli, Bacteroides forsythus, Bacteroides gracilis, Campylobacter rectus, Porphyromonas gingivalis, Selenomonas sputigena and Candida albicans in smokers. Statistically significant differences for Peptostreptococcus micros, Actinomyces naeslundii, Eubacterium lentum and Capnocytophaga gingivalis were detected in non-smokers. The isolation of bacteria belonging to the exogenous flora like E. coli, C. albicans and S. aureus in smokers microflora underscores the importance of the host which is adversely affected by cigarette smoking.     

Dental Health in Smokers with and without COPD

The association between chronic obstructive pulmonary disease (COPD) and periodontal disease is sparsely studied. The aim was to describe the co-variation of periodontitis and lung function impairment in smokers. The hypothesis was that the destructive processes in the mouth and the lungs are interdependent due to a general individual susceptibility to detrimental effects of tobacco smoke. Smokers with COPD (n = 28) stage II and III according to GOLD guidelines and smokers without COPD (n = 29) and healthy non-smokers (n = 23) participated in the study. The groups of smokers were matched for cumulative exposure to tobacco smoke. Radiographic, general and dental clinical examination, lung function measurements and quality of life (SF-36) assessment were conducted. The relationship between respiratory and dental outcomes was analyzed. Dental health, assessed by plaque, gingival bleeding, periodontal pocket depth and loss of teeth was impaired in the smokers compared with non-smokers with no major differences between smokers with and without COPD. There was, however, a weak correlation between periodontitis and emphysema/impaired diffusion capacity. Impaired quality of life was associated with smoking and impaired lung function but not influenced by dental status. In conclusion periodontitis was strongly associated with smoking, weakly associated with lung tissue destruction and very weakly or even not at all associated with chronic airflow limitation. The results indicate that, although there was a co-variation between periodontitis and pathologic lung processes in smokers, the risk of developing COPD, as defined by spirometric outcomes, is not associated with the risk of impaired dental health in smokers.     

Metabolic effects of cigarette smoking.

The inverse relationship between cigarette smoking and body weight, a potent obstacle to stopping smoking, may be due in part to effects of smoking on increasing whole body metabolism. Studies examining chronic and acute metabolic effects of smoking, as well as its constituent nicotine, are reviewed. Evidence suggests the absence of a chronic effect; most studies indicate that smokers and nonsmokers have similar resting metabolic rates (RMR) and that RMR declines very little after smoking cessation. Although an acute effect due to smoking is apparent, its magnitude is inconsistent across studies, possibly because of variability in smoke exposure or nicotine intake. In smokers at rest, the acute effect of smoking (and nicotine intake) appears to be significant but small (less than 10% of RMR) and transient (less than or equal to 30 min). However, the specific situations in which smokers tend to smoke may mediate the magnitude of this effect, inasmuch as smoking during casual physical activity may enhance it while smoking after eating may reduce it. Sympathoadrenal activation by nicotine appears to be primarily responsible for the metabolic effect of smoking, but possible contributions from nonnicotine constituents of tobacco smoke and behavioral effects of inhaling may also be important. Improved understanding of these metabolic effects may lead to better prediction and control of weight gain after smoking cessation, thus increasing the likelihood of maintaining abstinence.     

Effect of nicotine on glycosaminoglycan metabolism in rats.

Cigarette smoking has been established as a major risk factor for atherosclerosis and also for lung cancer. Nicotine is one of the major components of cigarette smoke which is believed to be partly responsible for the deleterious effect of cigarette smoke. There was significant alteration in the concentration of glycosaminoglycans (GAG) in rats exposed to cigarette smoke. Administration of nicotine to rats has been found to decrease many of GAG fractions in the aorta, liver and heart and increase in the lungs. The increase in GAG now observed in lung tissue in rats administered nicotine and those exposed to cigarette smoke may be involved in the increased incidence of lung cancer in smokers. Increased activity of many of GAG hydrolysing enzymes indicates increased degradation of GAG. Sulphate metabolism in the liver is also significantly altered by nicotine. Thus administration of nicotine to rats caused alteration in the metabolism of GAG which are similar to those observed on exposure of rats to cigarette smoke, indicating that nicotine content of the tobacco smoke may partly be responsible for the effect on GAG observed on exposure to cigarette smoke.     

Cigarette smoking enhances T cell activation and a Th2 immune response; an aspect of the pathophysiology in periodontal disease

Smoking is a strong risk factor for periodontitis. Treated patients who smoke show increased risk for further periodontal breakdown, despite receiving maintenance care. Previous work indicated that such patients have a monocytic cytokine response favoring Th2 activity. The purpose of this study was to investigate the T lymphocytic cytokine production representing Th1 and Th2 subpopulations in smokers and non-smokers. Venous blood was collected from 30 treated periodontitis patients (12 smokers) and 24 healthy subjects (12 smokers). Whole blood cell cultures were stimulated and interferon (IFN)-γ and interleukin (IL)-13 were measured in the culture supernatants, representing types 1 and 2 Th subpopulations, respectively. Unadjusted data showed that smokers had more lymphocytes, and higher levels of IFN-γ and IL-13, irrespective of being periodontal patient. However in a multivariate analysis, increased IFN-γ production was not significantly explained by smoking, while higher IL-13 was strongly explained by smoking (21%, p < 0.001). We suggest that the increased Th activity and specifically an elevated Th2 profile in smokers may constitute a risk for smoking patients which may induce conversion of periodontal stability into progressive disease. This phenomenon may be equally important in other conditions, where connective tissue and bone loss are hallmarks of disease pathophysiology.     

Chronic oral nicotine treatment protects against striatal degeneration in MPTP-treated primates

The present studies were done to investigate the effect of long-term nicotine treatment against nigrostriatal damage in non-human primates. Monkeys were administered nicotine in drinking water for 6 months to provide chronic but intermittent delivery as with smoking. Plasma nicotine levels ranged from 10 to 15 ng/mL, which were within the range in cigarette smokers. Animals were then lesioned with low doses of the dopaminergic neurotoxin MPTP for several months while nicotine was continued. The results showed that levels of striatal tyrosine hydroxylase, dopamine transporter, vesicular monoamine transporter, dopamine and nicotinic receptors were greater in nicotine-treated MPTP-lesioned primates than in lesioned animals not receiving nicotine. Nicotine had no effect in unlesioned animals. Monoamine oxidase activity was similar in unlesioned and lesioned animals treated with or without nicotine, suggesting that nicotine did not exert its effects through changes in MPTP or dopamine metabolism. MPTP-induced cell loss in the substantia nigra was unaffected by nicotine treatment, indicating that nicotine acts at the striatal level to restore/maintain dopaminergic function. These data further support the possibility that nicotine contributes to the lower incidence of Parkinson's disease in smokers.     

Relationship between cigarette yields,puffing patterns,and smoke intake: evidence for tar compensation?

The relationship between cigarette yields (of nicotine, tar, and carbon monoxide), puffing patterns, and smoke intake was studied by determining puffing patterns and measuring blood concentrations of nicotine and carboxy-haemoglobin (COHb) in a sample of 55 smokers smoking their usual brand of cigarette. Regression analyses showed that the total volume of smoke puffed from a cigarette was a more important determinant of peak blood nicotine concentration than the nicotine or tar yield of the cigarette, its length, or the reported number of cigarettes smoked on the test day. There was evidence of compensation for a lower tar yield over and above any compensation for nicotine. When nicotine yield was controlled for, smokers of lower-tar cigarettes not only puffed more smoke from their cigarettes than smokers of higher-tar cigarettes but they also had higher plasma nicotine concentrations, suggesting that they were compensating for the reduced delivery of tar by puffing and inhaling a greater volume of smoke. The results based on the COHb concentrations were consistent with this interpretation. If an adequate intake of tar proves to be one of the main motives for smoking, then developing a cigarette that is acceptable to smokers and also less harmful to their health will be much more difficult.     

Epidemiological study on improving the QOL and oral conditions of the aged--Part 2: Relationship between tooth loss and lifestyle factors for adults men

Oral health in early- and mid-adulthood is essential for the improvement of one's QOL, this study was investigated to include an epidemiological analysis of the relationship between tooth loss and life style, such as smoking, regular exercise, and the food habits of approximately 2,000 employees. Compared with the group with mild or no periodontal disease (CPI of 0, 1, or 2), the frequency of tooth loss in the group with advanced periodontal disease (CPI of 4) was 2.00 times (odds ratio, 2.00; 95% confidence limit, 1.37 to 2.93). The probability of tooth loss showed statistical significance in relation to smoking, alcohol drinking, and frequency of meals. Compared with non-smokers, the probability that current smokers will lose teeth is 1.53 times greater (odds ratio, 1.53; 95% confidence limit, 1.20 to 1.96). It was concluded that periodontal disease and smoking must be averted for preventing tooth loss.