The Cost of Canine Rabies on Four Continents

We estimated the economic impacts of canine rabies in Latin America, Africa and Asia. Direct and indirect costs of rabies post‐exposure prophylaxis, dog vaccination and control, rabies diagnostic testing and cattle mortality‐related costs were accounted for. The number of human deaths was updated from previous estimates based on population growth, and the costs associated with the risk of human mortality were incorporated. We accounted for uncertainty associated with the parameter estimates using a Monte Carlo simulation and estimated that the global burden of canine rabies is approximately $124 billion annually. This result illustrates the potential benefits that could be realized if canine rabies was eliminated and provides an important benchmark against which the cost of any potential elimination campaign can be compared.     

Validity of Internet-Based Longitudinal Study Data: The Elephant in the Virtual Room

Background

Internet-based data collection relies on well-designed and validated questionnaires. The theory behind designing and validating questionnaires is well described, but few practical examples of how to approach validation are available in the literature.

Objective

We aimed to validate data collected in an ongoing Internet-based longitudinal health study through direct visits to participants and recall of their health records. We demonstrate that despite extensive pre-planning, social desirability can still affect data in unexpected ways and that anticipation of poor quality data may be confounded by positive validation.

Methods

Dogslife is a large-scale, Web-based longitudinal study of canine health, in which owners of Labrador Retrievers were recruited and questioned at regular intervals about the lifestyle and health of their dogs using an Internet-based questionnaire. The Dogslife questionnaire predominantly consists of closed-answer questions. In our work, two separate validation methodologies were used: (1) direct interviews with 43 participants during visits to their households and (2) comparison of owner-entered health reports with 139 historical health records.

Results

Our results indicate that user-derived measures should not be regarded as a single category; instead, each measurement should be considered separately as each presents its own challenge to participants. We recommend trying to ascertain the extent of recall decay within a study and, if necessary, using this to guide data collection timepoints and analyses. Finally, we recommend that multiple methods of communication facilitate validation studies and aid cohort engagement.

Conclusions

Our study highlighted how the theory underpinning online questionnaire design and validation translates into practical data issues when applied to Internet-based studies. Validation should be regarded as an extension of questionnaire design, and that validation work should commence as soon as sufficient data are available. We believe that validation is a crucial step and hope our suggested guidelines will help facilitate validation of other Internet-based cohort studies.     

上颌腭侧阻生尖牙非手术与手术助萌的比较研究

目的探讨上颌腭侧阻生尖牙通过正畸开辟间隙等非手术助萌的适应证、矫治时间及其临床效果。方法选取9例患者的12颗上颌腭侧阻生尖牙为研究对象,通过曲面全景及头颅侧位片判断阻生尖牙在颌骨内的位置、牙齿的发育阶段及患者骨成熟阶段,通过正畸治疗配合头帽口外弓为阻生尖牙开辟间隙,定期拍摄曲面全景片观察阻生尖牙的萌出潜力。结果 7颗阻生尖牙自动萌出,3颗阻生尖牙采取外科开窗联合正畸牵引治疗,2颗阻生尖牙选择外科拔除。结论正畸开辟间隙后阻生尖牙成功萌出的主要因素可以概括为:萌出路径无干扰、骨成熟早期,根尖孔未闭合,而骨发育阶段比牙发育阶段更有指导意义。     

Cell crawling mediates collective cell migration to close undamaged epithelial gaps

Fundamental biological processes such as morphogenesis and wound healing involve the closure of epithelial gaps. Epithelial gap closure is commonly attributed either to the purse-string contraction of an intercellular actomyosin cable or to active cell migration, but the relative contribution of these two mechanisms remains unknown. Here we present a model experiment to systematically study epithelial closure in the absence of cell injury. We developed a pillar stencil approach to create well-defined gaps in terms of size and shape within an epithelial cell monolayer. Upon pillar removal, cells actively respond to the newly accessible free space by extending lamellipodia and migrating into the gap. The decrease of gap area over time is strikingly linear and shows two different regimes depending on the size of the gap. In large gaps, closure is dominated by lamellipodium-mediated cell migration. By contrast, closure of gaps smaller than 20 μm was affected by cell density and progressed independently of Rac, myosin light chain kinase, and Rho kinase, suggesting a passive physical mechanism. By changing the shape of the gap, we observed that low-curvature areas favored the appearance of lamellipodia, promoting faster closure. Altogether, our results reveal that the closure of epithelial gaps in the absence of cell injury is governed by the collective migration of cells through the activation of lamellipodium protrusion.