传染病传染速度在大区域内的关联建模仿真

研究传染病的扩散速度对病情的控制问题.传染病在扩散过程中,受到不同区域中人群组成、环境特征不同的影响,存在高度的非线性与随机性.传统的扩散模型通过高维度约束,扩散随机性较强,设定过多前提条件,导致模型复杂,效果不好.提出基于加权时态关联挖掘算法的传染病传染速度在大区域内的关联建模方法.提取传染病传染速度影响因素,根据上述影响因素,建立加权时态关联模型,计算不同影响因素的支持度,并建立候选项集树,实现传染速度估计.实验结果表明,利用改进算法进行传染病传染速度在大区域内关联建模,能够提高传染病传染速度仿真的真实度,得到精确的估计结果,满足传染病预防和控制的临床需求.     

烟草灰霉病侵染条件的研究

烟草灰霉病是黑龙江烟区新发现病害，个别地块已造成严重损失。自１９９０～１９９５年利用田间试验和控制条件接种方法，研究了烟草灰霉病病菌侵染来源和侵染规律，试验发现：①灰霉病菌Ｂｏｔｒｙｔｉｓｃｉｎｅｒｅａ侵染烟株的最适宜温度在１８℃左右，９℃以下或２７℃以上不能发生侵染，该菌发生侵染还必须满足９ｈ以上的湿润时间，１２～２４ｈ持续湿润利于侵染，光照对病菌侵染有抑制作用。②病菌的侵染来源主要是来自烟株病残体产生的分生孢子。③黑龙江烟区有两个侵染高峰，一个在６月中、下旬，另一个在８月中、下旬。这期间低温、多雨侵染率较高。     

两种拟青霉对烟蚜感染作用试验

为探讨利用拟青霉控制烟蚜的可能性,测定了粉拟青霉(Paecilomycesfarinosus)和玫烟色拟青霉(Paecilomycesfumosoroseus)对烟蚜[Myzusnicotianae(Blackman)]的感染致死率,发现粉拟青霉菌Pf 27菌株和玫烟色拟青霉菌Pf 30菌株对烟蚜有较好的感染致死作用。在处理后第3d和第5d,粉拟青霉菌Pf 27菌株对烟蚜的室内感染率分别为56 0%和98 0%,玫烟色拟青霉菌Pf 30菌株分别为10 0%和82 0%。用1 5×108个/mL的孢子悬浮液喷雾处理烟田烟株上的烟蚜,处理后第10d,Pf 27菌株和Pf 30菌株对烟蚜的感染率分别为77 2%和78 5%,这两个菌株均有进一步研究的价值。     

Predictive models of control strategies involved in containing indoor airborne infections

Recently developed control measure modeling approaches for containing airborne infections, including engineering controls with respiratory protection and public health interventions, are readily amenable to an integrated-scale analysis. Here we show that such models can be derived from an integrated-scale analysis generated from three different types of functional relationship: Wells-Riley mathematical model, competing-risks model, and Von Foerster equation, both of the key epidemiological determinants involved and of the functional connections between them. We examine mathematically the impact of engineering control measures such as enhanced air exchange and air filtration rates with personal masking combined with public health interventions such as vaccination, isolation, and contact tracing in containing the spread of indoor airborne infections including influenza, chickenpox, measles, and severe acute respiratory syndrome (SARS). If enhanced engineering controls could reduce the basic reproductive number (R0) below 1.60 for chickenpox and 3 for measles, our simulations show that in such a prepared response with public health interventions would have a high probability of containing the indoor airborne infections. Combinations of engineering control measures and public health interventions could moderately contain influenza strains with an R0 as high as 4. Our analysis indicates that effective isolation of symptomatic patients with low-efficacy contact tracing is sufficient to control a SARS outbreak. We suggest that a valuable added dimension to public health inventions could be provided by systematically quantifying transmissibility and proportion of asymptomatic infection of indoor airborne infection. Practical Implications We have developed a flexible mathematical model that can help determine the best intervention strategies for containing indoor airborne infections. The approach presented here is scalable and can be extended to include additional control efficacies. If a newly emergent airborne infection should appear, the model could be quickly calibrated to data and intervention options at the early stage of the outbreak. Data could be provided from the field to estimate value of R0, the serial interval between cases, the distributions of the latent, incubation, and infectious periods, case fatality rates, and secondary spread within important mixing groups. The combination of enhanced engineering control measures and assigned effective public health interventions would have a high probability for containing airborne infection.     

Role of air distribution in SARS transmission during the largest nosocomial outbreak in Hong Kong

Severe acute respiratory syndrome (SARS) is primarily transmitted by bio-aerosol droplets or direct personal contacts. This paper presents a detailed study of environmental evidence of possible airborne transmission in a hospital ward during the largest nosocomial SARS outbreak in Hong Kong in March 2003. Retrospective on-site inspections and measurements of the ventilation design and air distribution system were carried out on July 17, 2003. Limited on-site measurements of bio-aerosol dispersion were also carried out on July 22. Computational fluid dynamics simulations were performed to analyze the bio-aerosol dispersion in the hospital ward. We attempted to predict the air distribution during the time of measurement in July 2003 and the time of exposure in March 2003. The predicted bio-aerosol concentration distribution in the ward seemed to agree fairly well with the spatial infection pattern of SARS cases. Possible improvement to air distribution in the hospital ward was also considered. PRACTICAL IMPLICATIONS: Our study revealed the need for the development of improved ventilation and air-conditioning systems in an isolation ward or a general hospital ward for infectious respiratory diseases. The outbreak in Ward 8A, which was in a general hospital and could house nearly 40 patients, demonstrated the cross-infection risks of respiratory infectious diseases in hospitals if a potential highly infectious patient was not identified and isolated. Our example simulation, which extended the SARS Busters' design for an isolation room to Ward 8A, demonstrated that there was room for improvement to minimize cross-infection in large general hospital wards.     

Acute exposure to silica nanoparticles enhances mortality and increases lung permeability in a mouse model of Pseudomonas aeruginosa pneumonia

Background

The lung epithelium constitutes the first barrier against invading pathogens and also a major surface potentially exposed to nanoparticles. In order to ensure and preserve lung epithelial barrier function, the alveolar compartment possesses local defence mechanisms that are able to control bacterial infection. For instance, alveolar macrophages are professional phagocytic cells that engulf bacteria and environmental contaminants (including nanoparticles) and secrete pro-inflammatory cytokines to effectively eliminate the invading bacteria/contaminants. The consequences of nanoparticle exposure in the context of lung infection have not been studied in detail. Previous reports have shown that sequential lung exposure to nanoparticles and bacteria may impair bacterial clearance resulting in increased lung bacterial loads, associated with a reduction in the phagocytic capacity of alveolar macrophages.

Results

Here we have studied the consequences of SiO₂ nanoparticle exposure on Pseudomonas aeruginosa clearance, Pseudomonas aeruginosa-induced inflammation and lung injury in a mouse model of acute pneumonia. We observed that pre-exposure to SiO₂ nanoparticles increased mice susceptibility to lethal pneumonia but did not modify lung clearance of a bioluminescent Pseudomonas aeruginosa strain. Furthermore, internalisation of SiO₂ nanoparticles by primary alveolar macrophages did not reduce the capacity of the cells to clear Pseudomonas aeruginosa. In our murine model, SiO₂ nanoparticle pre-exposure preferentially enhanced Pseudomonas aeruginosa-induced lung permeability (the latter assessed by the measurement of alveolar albumin and IgM concentrations) rather than contributing to Pseudomonas aeruginosa-induced lung inflammation (as measured by leukocyte recruitment and cytokine concentration in the alveolar compartment).

Conclusions

We show that pre-exposure to SiO₂ nanoparticles increases mice susceptibility to lethal pneumonia but independently of macrophage phagocytic function. The deleterious effects of SiO₂ nanoparticle exposure during Pseudomonas aeruginosa-induced pneumonia are related to alterations of the alveolar-capillary barrier rather than to modulation of the inflammatory responses.

Electronic supplementary material

The online version of this article (doi:10.1186/s12989-014-0078-9) contains supplementary material, which is available to authorized users.     

新型牛蛙抗菌肽Temporin-La对金黄色葡萄球菌感染模型小鼠的治疗效果

目的探讨新型牛蛙抗菌肽Temporin-La对金黄色葡萄球菌感染模型小鼠的治疗效果。方法采用二倍稀释法检测抗菌肽Temporine-La对临床主要致病菌的最小抑菌浓度(minimum inhibitory concentration,MIC);透射电镜观察Temporine-La对金黄色葡萄球菌的作用效果;复制金黄色葡萄球菌表皮感染小鼠模型,分别用4 U/ml青霉素和10μg/ml Temporin-La进行治疗,另设生理盐水对照组和空白对照组,感染后第4天,对各组小鼠进行白细胞计数、细菌计数、血管内皮生长因子(vascular endothelial growth factor,VEGF)表达水平检测及病理组织切片观察。结果Temporin-La对革兰阳性菌的抑菌活性高于革兰阴性菌,其中对金黄色葡萄球菌的抑制作用最强;透射电镜观察显示,经100μg/ml Temporin-La处理的金黄色葡萄球菌出现了质壁分离的现象,细胞壁缺失或发生裂解,金黄色葡萄球菌发生裂解而死亡;感染后第4天,青霉素组和Temporin-La组白细胞数及创面下肌肉组织细菌数均明显低于生理盐水对照组(P<0.05或P<0.01),Temporin-La组小鼠血清VEGF的表达水平明显高于青霉素组和空白对照组(P<0.05),青霉素组和Temporin-La组小鼠的创口修复情况明显优于生理盐水对照组。结论 Temporin-La具有抗小鼠金黄色葡萄球菌感染的效果,为其临床应用提供了实验依据,也为抗感染治疗提供了新的思路。     

Viral hemorrhagic septicemia virus infection in Yellow perch, Perca flavescens, in Lake Erie

Viral hemorrhagic septicemia virus (VHSV) infects wild and hatchery fish in Europe, Japan, and the Great Lakes and Pacific regions of North America. The virus was associated with a large die-off of yellow perch, Perca flavescens, in Lake Erie in 2006. To determine the infection pattern of VHSV, we sampled yellow perch during the spring, summer, and fall of 2007 and 2008 in the central basin of Lake Erie during routine sampling by the Ohio Division of Wildlife with bottom trawls in nearshore, mid-depth, and offshore locations near the Chagrin River. The Ohio Department of Agriculture's Diagnostic Laboratories and the U.S. Fish and Wildlife Service's La Crosse Fish Health Center tested for VHSV from homogenized samples obtained from yellow perch kidney, spleen, and brain. At each lake sample location, we also measured temperature, dissolved oxygen, and conductivity. In both years, we found yellow perch infected with VHSV during a three-week period starting in the last week of spawning to early June. A high proportion of adult male and female yellow perch tested positive for VHSV during the infection period in our sample population. Infection appeared to be associated with temperatures between 12 and 18 °C and with significantly higher yellow perch densities during spawning. No large mortalities of yellow perch were observed during the VHSV infection period in 2007 and 2008.     

洁净手术室使用中应注意的几个问题

结合医院外科手术室工作实践中出现的问题，根据国家相关标准和规范的要求，提出解决问题的具体措施和建议。     

甜菜坏死黄脉病毒危害菠菜的研究初报

报导了甜菜坏死黄脉病毒感染菠菜的情况，建议种植过甜菜的地块不要种植菠菜