成人安氏Ⅱ1分类错牙合切牙牙槽骨高度及厚度研究

目的:本研究对成人安氏Ⅱ1分类不同垂直骨面型患者治疗前的锥形束CT（CBCT）进行三维重建,测量切牙牙槽骨的高度和厚度,探讨成人安氏Ⅱ1分类错牙合不同垂直骨面型牙槽骨高度及厚度是否存在相关性,为临床上此类错牙合的诊断、矫治及风险评估提供理论依据。方法: 筛选CBCT,将测试对象分成高、均、低角3组,每组20例,应用Invivo 5 软件进行测量,对相关数据进行分析。结果:不同垂直骨面型切牙牙槽骨高度及厚度存在统计学差异（P＜0.05）。结论:（1）成人安氏Ⅱ1分类错牙合牙槽骨高度和厚度与垂直骨面型之间存在相关性。（２）成人安氏Ⅱ1分类切牙牙槽骨厚度,高角组最薄,低角组最厚。（3）成人安氏Ⅱ1分类切牙牙槽骨高度,高角组最高,低角组最低。     

Hard and soft tissue changes and long-term stability after vertical height reduction genioplasty using biodegradable fixation

The aim of this work was to analyse the stability of vertical height reduction genioplasty using biodegradable material, as well as to determine vertical changes of hard and soft tissues during this procedure.Forty patients underwent vertical height reduction genioplasty using two types of biodegradable fixation (Biosorb FX^® or OSTEOTRANS-MX^®), combined with mandibular setback surgery. We assessed lateral cephalographs over time (pre-operation; immediately post-operation; 3 months, 6 months and 12 months post-operation).We found a mean vertical difference of 0.22 mm (standard deviation (SD) = 0.49 mm) at the menton point immediately post-operation, compared with 12 months post-operation. And there was no statistical significance(P > 0.05). The chin hard tissue remained stable from the immediate post-operation period to 1 year post-operation, and the chin soft tissue remained stable from 3 months to 1 year post-operation. The regression equation describing the replacement of hard tissue with soft tissue change, between pre-operation and 12 months post-operation is y = 0.590x + 0.885 (R² = 0.300, P < 0.001).We confirm that the use of biodegradable fixation is a stable method, in terms of skeletal tissues, and a relatively stable method, in terms of soft tissues. In vertical height reduction genioplasty, soft tissue does not reflect 100% of the vertical tissue reduction in hard tissues. This data may influence establishment of surgical treatment objectives.     

From the Cover: Enhancement of anammox by the excretion of diel vertical migrators

Measurements show that anaerobic ammonium oxidation with nitrite (anammox) is a major pathway of fixed nitrogen removal in the anoxic zones of the open ocean. Anammox requires a source of ammonium, which under anoxic conditions could be supplied by the breakdown of sinking organic matter via heterotrophic denitrification. However, at many locations where anammox is measured, denitrification rates are small or undetectable. Alternative sources of ammonium have been proposed to explain this paradox, for example through dissimilatory reduction of nitrate to ammonium and transport from anoxic sediments. However, the relevance of these sources in open-ocean anoxic zones is debated. Here, we bring to attention an additional source of ammonium, namely, the daytime excretion by zooplankton and micronekton migrating from the surface to anoxic waters. We use a synthesis of acoustic data to show that, where anoxic waters occur within the water column, most migrators spend the daytime within them. Although migrators export only a small fraction of primary production from the surface, they focus excretion within a confined depth range of anoxic water where particle input is small. Using a simple biogeochemical model, we suggest that, at those depths, the source of ammonium from organisms undergoing diel vertical migrations could exceed the release from particle remineralization, enhancing in situ anammox rates. The contribution of this previously overlooked process, and the numerous uncertainties surrounding it, call for further efforts to evaluate the role of animals in oxygen minimum zone biogeochemistry.Water column oxygen minimum zones (OMZs), where oxygen concentrations plummet to submicromolar levels (1), are responsible for approximately one-third of the total removal of fixed nitrogen from the oceans (2, 3). Several processes mediated by specialized prokaryotes convert fixed inorganic nitrogen (NH₄⁺, NO₂⁻, and NO₃⁻) to N₂ in anoxic waters. Canonical denitrification, consisting of dissimilatory NO₃⁻ reduction to NO₂⁻ (DNRN) followed by the further oxidation of organic matter with NO₂⁻ (the denitrification step), was long considered the dominant fixed N removal pathway in anoxic waters. Over the last decade, anammox has gained attention as a major sink of fixed N in nearly anoxic waters (O₂ < 10 mmol·m⁻³) (4, 5).Stoichiometric considerations would suggest a close coupling between denitrification and anammox (6, 7). Under anoxic conditions, the NH₄⁺ liberated by the remineralization of organic matter through DNRN and denitrification should accumulate in the water column because conventional (aerobic) nitrification cannot proceed. However, this accumulation is not observed in the cores of anoxic waters, where observed NH₄⁺ concentrations are generally much less than 1 mmol·m⁻³ (8). In these regions, oxidation of NH₄⁺ with NO₂⁻ by anammox is thought to be the major sink of NH₄⁺ (9). Given that no significant NH₄⁺ accumulation takes place in the cores of OMZs, the supply of NH₄⁺ by denitrification must be completely consumed by its consumption via anammox. This would lead to ∼70% of the total fixed nitrogen (N) removal occurring through denitrification, and about 30% from anammox, with some variability related to the stoichiometry of the organic matter respired (7, 10).However, in situ measurements of denitrification and anammox in anoxic waters have in most cases failed to show a close coupling between these two biogeochemical pathways. While measurements of fixed N removal with isotopically labeled substrates show anammox occurring in many OMZs, denitrification appears to be patchier (11). In incubation experiments, anammox proceeds as soon as labeled NH₄⁺ is added, while denitrification can sometimes lag by multiple days following the addition of organic matter (e.g., ref. 12). This suggests that anammox could proceed at low, uniform rates in anoxic waters, while denitrification could be intermittent in space and time, fueled by high organic matter input events (13). It is possible that, despite the local mismatch of observed rates, a stoichiometric balance between anammox and denitrification is realized as an average on large spatial and temporal scales (11). However, the current pool of measurements is not extensive enough to test this hypothesis by providing an integrated view of fixed N removal in the water column, and the observed decoupling between anammox and denitrification remains puzzling due to the cryptic ammonium source.Alternative sources of NH₄⁺, other than the byproduct of DNRN and denitrification, could be responsible for some of this decoupling. Different biogeochemical pathways can supply NH₄⁺ to anammox bacterial communities. These include dissimilatory nitrate reduction to ammonium (DNRA) (14), as well as diffusion and advection from sulfate-reducing sediments, or from microaerobic remineralization at the boundaries of anoxic waters. However, it is not clear whether DNRA, thermodynamically disfavored compared with DNRN and denitrification, is important in anoxic open waters, compared with sediments (15). Similarly, advection and diffusion of NH₄⁺ can be relevant at the boundaries of anoxic layers, or where anoxic waters impinge on sulfidic sediments (8), but are of limited importance in the anoxic cores of OMZs, which are characterized by weak circulation and mixing (16, 17), small NH₄⁺ gradients (8), and undetectable oxygen concentrations over water layers hundreds of meters thick (1).Here, we suggest that the excretion of NH₄⁺ by diel vertically migrating animals could play an important role in the N cycle of OMZs, and contribute to the decoupling of anammox and denitrification. As shown in DVM Association With Anoxic Waters, diel vertical migrations (DVM) of zooplankton and micronekton commonly reach the anoxic layers of the major OMZs of the open ocean. Because animals excrete reduced N mostly as NH₄⁺, they can fuel anammox directly, and decouple it from denitrification. Here, we present a first assessment of this process.The rest of the paper is organized as follows. In DVM Association With Anoxic Waters, we show the common occurrence of DVM across major OMZs by using acoustic data. In DVM Effects on the N Cycle in Anoxic Waters, we describe how the excretion of NH₄⁺ by vertical migrators can alter the balance between fixed N removal pathways, enhancing anammox. In Spatial Models of DVM Amplification of Anammox, we outline the results of an idealized, spatially resolved model of the nitrogen cycle in anoxic waters, to estimate the potential for anammox amplification by DVM. Finally, in Summary, we discuss the implications for OMZ biogeochemistry.     

Middle Mesial Canal Preparation Enhances the Risk of Fracture in Mesial Root of Mandibular Molars

IntroductionThe aim of this investigation was to evaluate the effect of the presence and preparation of middle mesial (MM) canals on the fracture resistance of the mesial root of mandibular molars.MethodsForty intact mesial roots of mandibular first molars having 2 (n = 20) or 3 (n = 20) independent canals from the furcation level for up to at least 5 mm apically were selected based on preoperative micro–computed tomographic scanning. The selected roots were then distributed into 2 experimental (n = 10) and 2 control groups (n = 10) according to the root length, canal configuration (2 or 3 independent canals), and root thickness at the furcation level. In the experimental groups 1 (2 independent canals) and 3 (3 independent canals), root canals were enlarged up to the ProTaper Next X3 rotary instrument (Dentsply Sirona, Ballaigues, Switzerland), whereas in groups 2 (2 independent canals) and 4 (3 independent canals) root canals were not prepared. The specimens were embedded in acrylic resin after their surfaces were coated with a thin layer of silicone and subjected to a fracture strength using a universal testing machine. The types of fracture extension and course were recorded and statistically compared with the chi-square test, whereas fracture strength was analyzed using 1-way analysis of variance and post hoc Tukey tests (α = 5%).ResultsNo statistical difference in fracture strength was observed between nonprepared roots with 2 (group 2, 696.1 ± 186.3 N) or 3 (group 4, 558.4 ± 154.6 N) independent canals (P > .05), whereas the lowest values were obtained in the prepared roots with an MM canal (groups 3, 377.1 ± 77.2 N) (P < .05). The mean fracture strength observed in the prepared roots with 2 canals (group 1, 528.4 ± 134.3 N) showed no statistically significant difference compared with nonprepared roots with 3 canals (group 4, 558.4 ± 154.6 N) (P > .05). The chi-square test revealed no significant differences in fracture extent, types, and courses among groups (P > .05). Fracture extensions in all groups were mostly central and buccal-central types, whereas the highest frequency of fracture course was the curved and zigzag types.ConclusionsThe fracture resistance of the mesial roots of the mandibular molars decreased after the preparation of mesial canals with large-tapered instruments. Preparation of the MM canal further diminished the fracture resistance of the mesial roots. The resultant fracture displayed a distinct pattern in the buccolingual plane.     

Risk factors for mother-to-child transmission of hepatitis C virus: Maternal high viral load and fetal exposure in the birth canal

Aim: Mother‐to‐child transmission (MTCT) is the major transmission pathway of hepatitis C virus (HCV) in children. However, its risk factors remain unsettled for introduction of putative intervention. Methods: Pregnant women screened for HCV and MTCT in children born to antibody‐positive mothers were prospectively studied in Tottori, Japan. Results: Among 41 856 screened women, 188 (0.45%) were HCV antibody‐positive, of whom 61% had detectable HCV RNA. While 10 of the 34 children (29%) born to high viral load (HVL: ≥6.0 × 10⁵ IU/mL) mothers were infected, none born to RNA‐detectable but non‐HVL mothers were infected (P < 0.001). MTCT among vaginally delivered children born to HVL mothers was analyzed. Children delivered after 4 h or more of labor were more frequently infected than were those born within 4 h of labor (P = 0.019). Premature rupture of fetal membranes was significantly more common in infected children than in uninfected children (P < 0.001). Durations of membrane rupture and labor were longer in infected children than in uninfected children (P = 0.008 and P = 0.040, respectively). Elective cesarean section that eliminates these risk factors, other than HVL, significantly reduced MTCT from nine of 22 (41%) to none of nine children (0%) (P = 0.032). Conclusion: Our data suggest that contamination of the fetus in the birth canal with infected maternal blood is a major risk factor for HCV MTCT, in addition to maternal HVL. To rationalize intervention by elective cesarean section, the natural history of infected children should be carefully evaluated.     

Testing children of mothers with HIV infection: experience in three south-west London HIV clinics

Objective

There are several reported cases of vertically infected children presenting with advanced HIV infection in the UK. The children of women with HIV infection are at increased risk of being infected. There are few data available on the number of such children that are yet to be tested for HIV. This study looked at the HIV testing status of children whose mothers attend HIV services at three south‐west London clinics.

Methods

Case notes of women attending the clinics from 1 January to 30 June 2009 were reviewed. When data were incomplete, women were prospectively interviewed.

Results

Case notes of 605 women were reviewed; 478 women had 1107 children. The majority of women (386; 81%) were of Black African ethnicity. Sixty‐one per cent (675 of 1107) of the children were known to have been tested for HIV. The children resident abroad were more likely to be untested compared with those resident in the UK; 186 of 255 (73%) vs. 246 of 852 (29%). A quarter (106 of 432) of the untested children were ≤18 years old; 49 (46%) of these were resident in the UK. The most common reason given by the mothers for not testing was a perceived ‘unlikely risk’.

Conclusions

A significant number of children at risk of vertically transmitted HIV infection, including 49 children ≤18 years and resident in the UK, were identified through this study. The mothers are being encouraged to have these children tested and a multidisciplinary team involving adult and paediatric HIV healthcare professionals has been set up to negotiate and facilitate testing.     

孕期人乳头状瘤病毒感染的结局分析

目的:探讨人乳头状瘤病毒(human papillomavirus,HPV)的感染分型及母婴垂直传播情况。方法:对2011年1月—2012年12月在复旦大学附属中山医院青浦分院产科门诊就诊的500例孕妇的宫颈脱落细胞进行HPV-DNA分型检测,并对HPV阳性孕妇分娩的新生儿的口咽部和生殖器黏膜细胞进行HPV-DNA分型检测,分析HPV亚型感染状况。结果:500例孕妇中HPV阳性者102例,感染率20.40%;感染HPV最常见的亚型为HPV16(4.2%)、HPV52(2.20%)、HPV33(1.80%)、HPV58(1.80%)、HPV18(1.60%)、HPV39(1.20%)。HPV阳性孕妇中,单型别感染88例(86.27%);多重型别感染14例(13.73%),其中二重感染11例,三重感染3例。母婴HPV垂直传播7例(6.86%)。25~30岁年龄段孕妇HPV感染率较高,不同孕期孕妇HPV感染率差异无统计学意义(P0.05)。结论:孕期HPV感染以HPV16型为主,并可母婴垂直传播;妊娠期妇女早期筛查对降低宫颈癌发病率和新生儿感染率非常必要。     

采用二维组织轨迹法(2DTT)对心室壁运动的探讨

缺血性心脏病是否存在左心室壁运动失调和心肌缺血有很大关系。心动超声图对左心室失调心壁运动的检测非常方便,没有任何损伤。在心动超声图左心室壁运动中,健康的部分在心室扩张末期壁厚是最小的,而后在心室收缩期壁厚增加。存在心肌梗塞的心室在收缩期比健康正常的心室壁厚度增加的能力要低下。扩张期和收缩期心室壁厚度没有变化和收缩期心室壁厚度反而变小的情况都存在。本文就其中的B超临床诊断功能作了说明与分析。     

种植体螺纹形状对骨界面应力分布的影响

目的研究种植体表面不同螺纹形状对种植体-骨界面应力分布的影响,以供临床筛选合适的种植系统。方法采用三维有限元法,分别对种植体施加30牛顿垂直和斜向45°两种方向的集中载荷,对不同螺纹顶角螺纹形状分别为对称、上平下斜、上斜下平的种植体-骨界面进行应力分析。结果螺纹形状为上平下斜式种植体的应力峰值较小;各组模型的最大位移值相近,但螺纹形状对称、顶角为30°者位移极值最小,为3.84×10-4mm和85.61×10-4mm。结论螺纹形状对种植体-骨界面的应力分布有影响,设计和选择种植系统时应全面考虑。     

Subendocardial Steal Effect Seen with Real-Time Perfusion Imaging at Low Emission Power during Adenosine Stress: Replenishment M-Mode Processing Allows Visualization of Vertical Steal

We present a patient in whom power pulse inversion imaging clearly demonstrated a subendocardial myocardial perfusion defect during contrast vasodilator stress using adenosine. The defect was best appreciated with M-mode postprocessing of power pulse inversion imaging data.