吸烟对种植体周围炎患者龈下菌群、龈沟液炎症因子和RANKL/OPG比值的影响

摘要 目的：探讨吸烟对种植体周围炎患者龈下菌群分布、龈沟液炎症因子白细胞介素-4（IL-4）、白细胞介素-5（IL-5）、白细胞介素-6（IL-6）、白细胞介素-8（IL-8）、白细胞介素-17（IL-17）和核因子-κB受体活化因子配体/骨保护素（RANKL/OPG）比值的影响。方法：选择2019年3月至2022年3月首都医科大学附属北京友谊医院口腔科收治的种植体周围炎患者99例（共151颗种植体）,根据是否吸烟分为吸烟组（45例,68颗种植体）和非吸烟组（54例,83颗种植体）,比较两组患者种植体牙周改良菌斑指数（mPLI）、牙龈出血指数（GBI）、种植体周围探诊深度（PPD）,采集两组龈下菌斑进行细胞培养并进行菌种鉴定,分析两组龈下菌群分布情况,比较两组龈沟液中IL-4、IL-5、IL-6、IL-8、IL-17、RANKL/OPG比值。结果：吸烟组mPLI、GBI、PPD高于不吸烟组（P＜0.05）。吸烟组厌氧菌检出率高于非吸烟组（P＜0.05）,有益菌检出率低于非吸烟组（P＜0.05）,两组需氧菌检出率比较差异无统计学意义（P＞0.05）。吸烟组龈沟液IL-4、IL-5、IL-6、IL-8、IL-17水平均高于非吸烟组（P＜0.05）。吸烟组龈沟液RANKL水平、RANKL/OPG比值高于非吸烟组（P＜0.05）,OPG水平低于非吸烟组（P＜0.05）。结论：吸烟可导致种植体周围炎患者龈下厌氧菌增加,加重炎症反应,增加牙槽骨吸收风险。     

Effects of fronto-occipital artificial cranial vault modification on the cranial base and face.

Artificial reshaping of the cranial vault has been practiced by many human groups and provides a natural experiment in which the relationships of neurocranial, cranial base, and facial growth can be investigated. We test the hypothesis that fronto-occipital artificial reshaping of the neurocranial vault results in specific changes in the cranial base and face. Fronto-occipital reshaping results from the application of pads or a cradle board which constrains cranial vault growth, limiting growth between the frontal and occipital and allowing compensatory growth of the parietals in a mediolateral direction. Two skeletal series including both normal and artificially modified crania are analyzed, a prehistoric Peruvian Ancon sample (47 normal, 64 modified crania) and a Songish Indian sample from British Columbia (6 normal, 4 modified). Three-dimensional coordinates of 53 landmarks were measured with a diagraph and used to form 9 finite elements as a prelude to finite element scaling analysis. Finite element scaling was used to compare average normal and modified crania and the results were evaluated for statistical significance using a bootstrap test. Fronto-occipitally reshaped Ancon crania are significantly different from normal in the vault, cranial base, and face. The vault is compressed along an anterior-superior to posterior-inferior axis and expanded along a mediolateral axis in modified individuals. The cranial base is wider and shallower in the modified crania and the face is foreshortened and wider with the anterior orbital rim moving inferior and posterior towards the cranial base. The Songish crania display a different modification of the vault and face, indicating that important differences may exist in the morphological effects of fronto-occipital reshaping from one group to another.     

Two-phase species–time relationships in North American land birds

The species–time relationship (STR) is a macroecological pattern describing the increase in the observed species richness with the length of time censused. Understanding STRs is important for understanding the ecological processes underlying temporal turnover and species richness. However, accurate characterization of the STR has been hampered by the influence of sampling. I analysed STRs for 521 breeding bird survey communities. I used a model of sampling effects to demonstrate that the increase in richness was not due exclusively to sampling. I estimated the time scale at which ecological processes became dominant over sampling effects using a two‐phase model combining a sampling phase and either a power function or logarithmic ecological phase. These two‐phase models performed significantly better than sampling alone and better than simple power and logarithmic functions. Most community dynamics were dominated by ecological processes over scales <5 years. This technique provides an example of a rigorous, quantitative approach to separating sampling from ecological processes.     

Marginality: scale determined processes and the conservation of the British butterfly fauna

Marginality describes the impact that environmental and landscape factors have in decreasing the probability of population survival and persistence. It may be imposed by extreme conditions or resource scarcity. Typically, it affects populations at the range edge but can also affect populations within the core of ranges, and produces a number of symptoms: characteristically demographic, but also morphological, physiological, biochemical and genetic. In this paper, the causes and effects of marginality on British butterflies are compared in edge and centre of range populations. Issues of temporal and spatial scales are examined, as is the relevance of marginality to the conservation of single and multiple species populations. The recognition of marginality questions the appropriateness of many so-called spatially realistic models of populations and highlights areas of research which have hitherto been ignored. Projected changes in land use and climate have implications for marginality in core and peripheral populations; in view of this, current scales of mapping are found to be unsuitable for monitoring fragmentation and the increasing marginalization of butterfly species in the British landscape.     

Stomatal responses to increased CO2: implications from the plant to the global scale

Increased atmospheric CO₂ often but not always leads to large decreases in leaf conductance. Decreased leaf conductance has important implications for a number of components of CO₂ responses, from the plant to the global scale. All of the factors that are sensitive to a change in soil moisture, either amount or timing, may be affected by increased CO₂. The list of potentially sensitive processes includes soil evaporation, run-off, decomposition, and physiological adjustments of plants, as well as factors such as canopy development and the composition of the plant and microbial communities. Experimental evidence concerning ecosystem-scale consequences of the effects of CO₂ on water use is only beginning to accumulate, but the initial indication is that, in water-limited areas, the effects of CO₂-induced changes in leaf conductance are comparable in importance to those of CO,₂-induced changes in photosynthesis. Above the leaf scale, a number of processes interact to modulate the response of canopy or regional evapotran-spiration to increased CO₂. While some components of these processes tend to amplify the sensitivity of evapo-transpiration to altered leaf conductance, the most likely overall pattern is one in which the responses of canopy and regional evapotranspiration are substantially smaller than the responses of canopy conductance. The effects of increased CO₂ on canopy evapotranspiration are likely to be smallest in aerodynamically smooth canopies with high leaf conductances. Under these circumstances, which are largely restricted to agriculture, decreases in evapotranspiration may be only one-fourth as large as decreases in canopy conductance. Decreased canopy conductances over large regions may lead to altered climate, including increased temperature and decreased precipitation. The simulation experiments to date predict small effects globally, but these could be important regionally, especially in combination with radiative (greenhouse) effects of increased CO₂.     

Do migrant birds have more pointed wings?: A comparative study

Summary Do birds that migrate over longer distances have more pointed wings than more sedentary birds? Within several bird genera, species differ considerably in their migration distances. This makes it possible to study the extent to which different taxa show similar morphological solutions to common selection pressures. I selected 14 species, two from each of seven passerine genera, to maximize within-genus differences in migration distance. Wing lengths and the lengths of eight primary feathers around the wing tip were measured to assess wing length and shape. Primary lengths were transformed to take into account the allometric relationship between the length of each feather and wing length and then collapsed into summary measures of shape by principal component analysis. I used the method of independent contrasts to address the effects of phylogeny. Wing length showed no relationship with migration distance. There was a correlation between migration distance and wing shape. It is concluded that long-distance migration has resulted in convergent morphological evolution of long distal and short proximal primaries, resulting in wing tips close to the leading edge of the wing.     

Recolonization of estuarine organisms: effects of microcosm size and pesticides

Two six-week laboratory experiments were conducted to evaluate effects of pesticides and microcosm size on benthic estuarine macroinvertebrate recolonization. Sediments fortified with the pesticides (fenvalerate: controls, 5 (low) and 50 μg g⁻¹ wet sediment (high); endosulfan: controls, 1 (low) and 10 μg g⁻¹ wet sediment (high)) were fine-grained, organically rich (approximately 3.5% organic carbon and 22% dry weight) material. Relative dominance of the four most abundant taxa in both experiments was consistent among treatments with few exceptions. The amphipod,Corophium acherusicum, dominated abundance in both experiments. In the fenvalerate experiment, large trays (400 cm²) contained significantly (p<0.05) more total number of taxa (TNT) than small microcosms (144 cm²) but tray size was not significantly related to total number of organisms (TNO). When size was adjusted to a common unit area, small trays contained significantly more TNO than large containers. Adjusted abundance of small trays was 2.5 times that of large containers; a ratio close to that of microcosm sizes (i.e., 2.8). This result suggests that larval supply may have been inadequate to ‘aturate’ the available sediment in large containers. Fenvalerate significantly reduced abundance in the high treatment compared to both controls and low treatment but low treatment was not significantly different from controls. The amphipod,Corophium acherusicum, accounted for most of the decrease in abundance in response to fenvalerate. The holothruroid,Leptosynpta sp. and the polychaete,Mediomastus ambiseta, increased in abundance significantly with increased concentration of fenvalerate. Combined effects of actual microcosm size and concentration of endosulfan were not significant for TNO or TNT. As in the fenvalerate experiment, adjusted abundance of small microcosms was 2.6 times that of large trays which approximated the ratio of unit area between microcosm sizes. Abundance of a few taxa responded significantly to adjusted and unadjusted unit area. Abundance of the tunicate,Molgula manhattensis, increased significantly with increased concentration of endosulfan. Abundance was affected by sample location (e.g., interiorvs exterior cores) within microcosms. Abundance adjusted to unit area resulted in significantly greater TNO in externalvs internal cores. This has importance for sequential sub-sampling of microcosms to determine temporal dynamics. Statistically significant effects were measured in benthic community structure associated with microcosm size; however, the magnitude was relatively small. There appears to be no major biological reason to select one microcosm size over the other for screening for contaminant effects. Where feasible, the small trays provide savings in sample preparation and analysis, allow more replicates where laboratory space is limiting and generate less chemical waste. These benefits may be off-set by less ‘artifacts’ associated with edge effects of larger microcosms and the need for a larger mass of sediment to accommodate additional analytical requirements (e.g., thin vertical surficial samples to refine contaminant exposure at the sediment/water interface).     

Uncertain branch lengths, taxonomic sampling error, and the egg to body size allometry in temperate butterflies (Lepidoptera)

The allometry of egg to body size in temperate butterflies, and the relationships between egg size and larval host structure, taxonomy, voltinism, and duration of the egg stage, are investigated using cross-species analysis and the comparative analysis of independent contrasts. In addition, the effect of two sources of uncertainty that may affect continuous data when treated under a statistical, comparative, framework, is assessed: (1) unknown evolutionary distances, and (2) taxonomic representativity (proportion of species of a given taxon, from which data are available). It is suggested that the effects of taxonomic under-representation could be important in comparative, quantitative studies, but this problem may be tempered by means of weighted regression. Under the assumption that taxonomy represents butterfly phylogeny, egg and adult body size are related by negative allometry (i.e. the slope of the line fitted to the logarithmically transformed data is lower than 1.0). However, the precise slope (0.2-0.9) depends on the method used, branch lengths, and taxonomic sampling. There is evidence for a relationship between a species' voltinism and the number of days it spends in the egg stage, as well as between adult butterfly size and the gross structure of the plants used as larval hosts (woody plants or herbs). Egg size proves to be related to foodplant taxonomy, voltinism, and duration of the egg stage when the data are analysed using species means, but these relationships become non-significant when the comparative method is employed.     

Some comments on coordinate-free and scale-invariant methods in morphometrics

The unusual strategy for comparing biological shapes is to use some kind of superimposition of the two forms under study and then look at the "residuals" as the shape change. In this paper, I take a careful look at this general strategy and point out some subtle but inherent and important pitfalls. Additionally an alternative approach based on Euclidean Distance Matrix representation is presented. It is applicable to two- as well as three-dimensional objects.     

Determination of electric current distributions in animals and humans exposed to a uniform 60-Hz high-intensity electric field

The thermographic method for determining specific absorption rate (SAR) in animals and models of tissues or bodies exposed to electromagnetic fields was applied to the problem of quantifying the current distribution in homogeneous bodies of arbitrary shape exposed to 60-Hz electric fields. The 60-Hz field exposures were simulated by exposing scale models of high electrical conductivity to 57.3-MHz VHF fields of high strength in a large 3.66 × 3.66 × 2.44-m TE₁₀₁ mode resonant cavity. After exposure periods of 2–30 s, the models were quickly disassembled so that the temperature distribution (maximum value up to 7 °C) along internal cross-sectional planes of the model could be recorded thermographically. The SAR, W′, calculated from the temperature changes at any point in the scale model was used to determine the SAR, W, for a full-scale model exposed to a 60-Hz electric field of the same strength by the relation W = (60/ f² · (σ′/σ) · W′ where f′ is the model exposure frequency, σ′ is the conductivity of the scale model at the VHF exposure frequency, and σ is the conductivity of the full-scale subject at 60 Hz. The SAR was used to calculate either the electric field strength or the current density for the full-scale subject. The models were used to simulate the exposure of the full-scale subject located either in free space or in contact with a conducting ground plane. Measurements made on a number of spheroidal models with axial ratios from 1 to 10 and conductivity from 1 to 10 s/m agreed well with theoretical predictions. Maximum current densities of 200 nA/cm² predicted in the ankles of man models and 50 nA/cm² predicted in the legs of pig models exposed to 60-Hz fields at 1kV/m agreed well with independent measurements on full-scale models.