Surviving in the High Arctic: dental variation in a casually introduced population of Microtus rossiaemeridionalis (Arvicolinae,Rodentia) on Svalbard

A human‐mediated invasion of a temperate rodent Microtus rossiaemeridionalis on the High Arctic Archipelago of Svalbard in the first half of the 20th century provides an opportunity to explore extent and rate of morphological divergence over decades of isolation. We studied dental size and morphology in 124 voles captured on Svalbard (Spitsbergen) in 1997–2005 and compared the data to mainland conspecific populations across northern Eurasia. Both dental and cranial sizes in the Svalbard population fall within the limits of natural variation of the species. Dental morphology suggests that the population experiences strong effects of isolation as indicated by the significant increase in the frequency of rare dental morphs, possibly caused by inbreeding. No evidence for directional shift towards increased or decreased complexity of the morphotype dental patterns is revealed. Although the population on Svalbard is phenotypically different from the mainland populations (due to increased frequency of rare morphs), those differences are not enough to support the idea of initial rapid evolution related to colonization. The limited spatial extent and environmental homogeneity of suitable habitats on the island allowed the species to initially multiply but not to diversify so that the species exhibits phenotypic conservatism but suffers the consequences of small population size.     

Potential mechanisms for the effects of tea extracts on the attachment,biofilm formation and cell size of Streptococcus mutans

Tea can inhibit the attachment of Streptococcus mutans to surfaces and subsequent biofilm formation. Five commercial tea extracts were screened for their ability to inhibit attachment and biofilm formation by two strains of S. mutans on glass and hydroxyapatite surfaces. The mechanisms of these effects were investigated using scanning electron microscopy (SEM) and phytochemical screening. The results indicated that extracts of oolong tea most effectively inhibited attachment and extracts of pu-erh tea most effectively inhibited biofilm formation. SEM images showed that the S. mutans cells treated with extracts of oolong tea, or grown in medium containing extracts of pu-erh tea, were coated with tea components and were larger with more rounded shapes. The coatings on the cells consisted of flavonoids, tannins and indolic compounds. The ratio of tannins to simple phenolics in each of the coating samples was ～3:1. This study suggests potential mechanisms by which tea components may inhibit the attachment and subsequent biofilm formation of S. mutans on tooth surfaces, such as modification of cell surface properties and blocking of the activity of proteins and the structures used by the bacteria to interact with surfaces.     

ON ALLOPTOX (LAGOMORPHA, OCHOTONIDAE)FROM THE MIDDLE MIOCENE OF TONGXIN, NINGXIA HUI AUTONOMOUS REGION, CHINA

<正> Rather abundant sample of Alloptox, including skulls, maxillae, mandibles and isolated teeth, was collected from the middle Miocene of Tongxin County, Ningxia Hui Autonomous Region during the two field seasons in 1985 and 1986, when reconnaissance and geological mapping of the middle Miocene in this region were conducted by a joint party of the Institute of Vertebrate Paleontology and Paleoanthropology, Academia Sinica (IVPP) and the Bureau of Geology, Ningxia Hui Autonomous Region. The specimens came from 18 localities pertaining to 9 levels in a sequence of middle Miocene fluviatile sediments with a thickness of ca. 200m. Except for the specimens assigned to Alloptox sp. from locality Taoziliang, all are recognized as Alloptox gobiensis. The present paper deals with only their dental morphology which is probably phylogenetically significant. Altogether 327 specimens of Alloptox gobiensis and 27 specimens of Alloptox sp. have been described. The text figures are drawn by the authors and Mrs. Yang Mingwan. All teeth are presented as left ones, the abbreviatd word "inv" is used under the figures of right teeth. All specimens are stored in IVPP under the inventory number V8822-V8839. The authors are much obliged to Prof. Qiu Zhanxiang for reading and correcting the English version of this paper.     

新型光纤光学相干层析系统在龋齿诊断中的应用

早期龋齿导致牙齿内部脱矿,使得该区域折射率发生变化,从而导致其后向散射系数增加。利用一种新型的光学相干层析（OCT）系统可以进行口腔龋齿疾病的诊断。该全光纤系统快速准确地获得了人体正常离体牙和具有龋变的离体牙的OCT图像。对比它们的后向散射系数,首次发现具有龋变的离体牙齿的后向散射系数是正常离体牙齿组织的数倍。采用此方法可以对龋齿及早期龋齿进行诊断,对于龋齿早期诊断研究具有重要的意义。     

The effects of plaque morphology and material properties on peak cap stress in human coronary arteries

Heart attacks are often caused by rupture of caps of atherosclerotic plaques in coronary arteries. Cap rupture occurs when cap stress exceeds cap strength. We investigated the effects of plaque morphology and material properties on cap stress. Histological data from 77 coronary lesions were obtained and segmented. In these patient-specific cross sections, peak cap stresses were computed by using finite element analyses. The finite element analyses were 2D, assumed isotropic material behavior, and ignored residual stresses. To represent the wide spread in material properties, we applied soft and stiff material models for the intima. Measures of geometric plaque features for all lesions were determined and their relations to peak cap stress were examined using regression analyses. Patient-specific geometrical plaque features greatly influence peak cap stresses. Especially, local irregularities in lumen and necrotic core shape as well as a thin intima layer near the shoulder of the plaque induce local stress maxima. For stiff models, cap stress increased with decreasing cap thickness and increasing lumen radius (R = 0.79). For soft models, this relationship changed: increasing lumen radius and increasing lumen curvature were associated with increased cap stress (R = 0.66). The results of this study imply that not only accurate assessment of plaque geometry, but also of intima properties is essential for cap stress analyses in atherosclerotic plaques in human coronary arteries.     

Effect of tissue properties,shape and orientation of microcalcifications on vulnerable cap stability using different hyperelastic constitutive models

Approximately half of all cardiovascular deaths associated with acute coronary syndrome occur when the thin fibrous cap tissue overlying the necrotic core in a coronary vessel is torn, ripped or fissured under the action of high blood pressure. From a biomechanics point of view, the rupture of an atheroma is due to increased mechanical stresses in the lesion, in which the ultimate stress (i.e. peak circumferential stress (PCS) at failure) of the tissue is exceeded. Several factors including the cap thickness, morphology, residual stresses and tissue composition of the atheroma have been shown to affect the PCS. Also important, we recently demonstrated that microcalcifications (μCalcs>5 µm are a common feature in human atheroma caps, which behave as local stress concentrators, increasing the local tissue stress by at least a factor of two surpassing the ultimate stress threshold for cap tissue rupture. In the present study, we used both idealized µCalcs with spherical shape and actual µCalcs from human coronary atherosclerotic caps, to determine their effect on increasing the circumferential stress in the fibroatheroma cap using different hyperelastic constitutive models. We have found that the stress concentration factor (SCF) produced by μCalcs in the fibroatheroma cap is affected by the material tissue properties, μCalcs spacing, aspect ratio and their alignment relative to the tensile axis of the cap.     

双歧杆菌三联活菌胶囊对动脉粥样硬化患者血脂、颈动脉斑块和肠道菌群的影响

目的 探讨双歧杆菌三联活菌胶囊辅助治疗颈动脉粥样硬化患者及其对患者血脂、颈动脉斑块和肠道菌群的影响。方法 选择2017年1月至2017年10月在我院门诊治疗的颈动脉粥样硬化患者84例,随机分为观察组和对照组各42例。对照组患者均予以瑞舒伐他汀（10 mg/次,1次/d）+肠溶阿司匹林片（100 mg/次,1次/d）口服治疗,并根据病情酌情给予降压、降糖等治疗。观察组患者在对照组基础上加用双歧杆菌三联活菌胶囊630 mg/次,3次/d,温水口服。两组患者疗程均为6个月。观察两组患者治疗前后血脂指标[总胆固醇（TC）、甘油三脂（TG）、高密度脂蛋白胆固醇（HDL-C）和低密度脂蛋白胆固醇（LDL-C）]水平、颈动脉斑块指标[颈动脉斑块内‒中膜厚度（IMT）及斑块面积）及肠道菌群数量（双歧杆菌、乳杆菌和大肠埃希菌）的变化。结果 治疗6个月后,两组患者TC、TG和LDL-C水平较治疗前均明显下降,HDL-C水平较治疗前均有明显上升（P<0.05）,且观察组变化幅度较对照组更明显（P<0.05）;两组患者颈动脉IMT及斑块面积较治疗前均明显下降（P<0.05）,且观察组下降幅度幅度较对照组更明显（P<0.05）;两组患者肠道双歧杆菌和乳杆菌数量较治疗前明显上升,大肠埃希菌数量较治疗前明显下降（P<0.05或P<0.01）,且观察组变化幅度幅度较对照组更明显（P<0.05）。结论 双歧杆菌三联活菌胶囊对颈动脉粥样硬化患者具有良好的协同降脂作用,并能延缓和逆转颈动脉粥样硬化,降低IMT及斑块面积。其作用机制可能与其能纠正肠道菌群紊乱,增加肠道有益菌数量,减少致病菌数量密切相关。     

动脉粥样硬化斑块钙化机制的研究进展

心血管疾病中动脉粥样硬化斑块的钙化是动脉粥样硬化的临床标志之一,主要发生在动脉血管的内膜.动脉粥样硬化斑块核心的钙化不会增加斑块的易损性,而粥样斑块纤维帽上的微钙化会加强纤维帽的周向应力,致使斑块的易损性增加.动脉粥样硬化斑块的钙化机制包括被动钙化和主动钙化,被动钙化受激素和局部信号的调节,主动钙化机制涉及复杂的细胞生命过程,基质囊泡、细胞凋亡、外泌体、氧化应激反应和细胞自噬等均参与了钙化过程.本文对动脉粥样硬化斑块的钙化机制的进展进行综述.