水环境中耐药菌污染与危害研究进展

细菌在抗菌药选择性压力下产生耐药性并可传代,通过质粒和整合子等可移动基因元件将耐药基因在相同或不同种属中广泛传播,导致细菌多重耐药,并可通过多种途径进入水体,水环境日益成为庞大的耐药基因库,为致病菌及条件致病菌提供获得大量耐药基因的机会,若多重耐药菌再次侵入人体,可能引发严重的公共卫生问题。     

Street Vended Food in Developing World: Hazard Analyses

Street food vending has become an important public health issue and a great concern to everybody. This is due to widespread food borne diseases, due to the mushrooming of wayside food vendors who lack an adequate understanding of the basic food safety issues. Major sources contributing to microbial contamination are the place of preparation, utensils for cooking and serving, raw materials, time and temperature abuse of cooked foods and the personal hygiene of vendors. Various studies have identified the sources of food safety issues involved in street foods to be microorganism belonging to the genus Bacillus, Staphylococcus, Clostridium, Vibrio, Campylobacter, Listeria, Salmonella. Application of sound risk analysis policies is being advocated to provide a scientific base to the host of risk management option which India may need to explore to ensure public health and safety.     

The Mean of the Inverse of a Punctured Normal Distribution and Its Application

The fundamental properties of a punctured normal distribution are studied. The results are applied to three issues concerning X/Y where X and Y are independent normal random variables with means μ_X and μ_Y respectively. First, estimation of μ_X/μ_Y as a surrogate for E(X/Y) is justified, then the reason for preference of a weighted average, over an arithmetic average, as an estimator of μ_X/μ_Y is given. Finally, an approximate confidence interval for μ_X/μ_Y is provided. A grain yield data set is used to illustrate the results. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Population fluctuations and regulation in great snipe: a time-series analysis

1. During the last centuries, the breeding range of the great snipe Gallinago media has declined dramatically in the western part of its distribution. To examine present population dynamics in the Scandinavian mountains, we collected and analysed a 19-year time series of counts of great snipe males at leks in central Norway, 1987-2005. 2. The population showed large annual fluctuations in the number of males displaying at lek sites (range 45-90 males at the peak of the mating season), but no overall trend. 3. We detected presence of direct density-dependent mechanisms regulating this population. Inclusion of the density-dependent term in a Ricker-type model significantly improved the fit with observed data (evaluated with Parametric Bootstrap Likelihood Ratio tests and Akaike's Information Criterion for small sample size). 4. An analysis of (a number of a priori likely) environmental covariates suggests that the population dynamics were affected by conditions influencing reproduction and survival of offspring during the summer, but not by conditions influencing survival at the wintering grounds in Africa. This is in contrast to many altricial birds breeding in the northern hemisphere, and supports the idea that population dynamics of migratory nidifugous birds are more influenced by conditions during reproduction. 5. Inclusion of these external factors into our model improved the detectability of density dependence. This illustrates that allowing for external effects may increase statistical power of density dependence tests and thus be of particular importance in relatively short time series. 6. In our best model of the population dynamics, two likely density-independent offspring survival covariates explained 47.3% of the variance in great snipe numbers (predation pressure estimated by willow grouse reproductive success and food availability estimated by the amount of precipitation in June), whereas density dependence explained 35.5%. Demographic stochasticity and unidentified environmental stochasticity may account for the remaining 17.2%.     

Actin dynamics in Amoeba proteus motility

Summary. We studied the distribution of the endogenous Arp2/3 complex in Amoeba proteus and visualised the ratio of filamentous (F-actin) to total actin in living cells. The presented results show that in the highly motile Amoeba proteus, Arp2/3 complex-dependent actin polymerisation is involved in the formation of the branching network of the contractile layer, adhesive structures, and perinuclear cytoskeleton. The aggregation of the Arp2/3 complex in the cortical network, with the exception of the uroid and advancing fronts, and the spatial orientation of microfilaments at the leading edge suggest that actin polymerisation in this area is not sufficient to provide the driving force for membrane displacement. The examined proteins were enriched in the pinocytotic pseudopodia and the perinuclear cytoskeleton in pinocytotic amoebae. In migrating amoebae, the course of changes in F-actin concentration corresponded with the distribution of tension in the cell cortex. The maximum level of F-actin in migrating amoebae was observed in the middle-posterior region and in the front of retracting pseudopodia. Arp2/3 complex-dependent actin polymerisation did not seem to influence F-actin concentration. The strongly condensed state of the microfilament system could be attributed to strong isometric contraction of the cortical layer accompanied by its retraction from distal cell regions. Isotonic contraction was limited to the uroid. Correspondence and reprints: Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, ulica Pasteura 3, 02-093 Warszawa, Poland.     

An estimate of the lower limit of global fungal diversity

We conservatively estimate that there is a minimum of 712,000 extant fungal species worldwide, but we recognize that the actual species richness is likely much higher. This estimate was calculated from the ratio of fungal species to plant species for various ecologically defined groups of fungi in well-studied regions, along with data on each groups’ level of endemism. These calculations were based on information presented in the detailed treatments of the various fungal groups published in this special issue. Our intention was to establish a lower boundary for the number of fungal species worldwide that can be revised upward as more information becomes available. Establishing a lower boundary for fungal diversity is important as current estimates vary widely, hindering the ability to include fungi in discussions of ecology, biodiversity and conservation. Problems inherent in making these estimates, and the impact that additional data on fungal and plant species diversity will have on these estimates are discussed.     

Aalen Additive Hazards Change-Point Model

We study a test comparing the full Aalen additive hazards modeland the change-point model, and suggest how to estimate theparameters of the change-point model. We also study a test forno change-point effect. Both tests are provided with large sampleproperties and a resampling method is applied to obtain p-values.The finite-sample properties of the proposed inference proceduresand estimators are assessed through a simulation study. Themethods are further applied to a dataset concerning myocardialinfarction.     

2013~2017年黑龙江省居民病伤死亡构成统计分析

摘要 目的：分析2013~2017年黑龙江省居民疾病死亡构成情况,为提高全省居民的防病治病意识及加强居民的健康生活理念提供参考。方法：采用国家卫生统计网络直报系统及数理统计方法对2013~2017年全省居民疾病发病死亡构成变化进行分析。结果：全省居民死亡性别比例表现为男性高于女性,死亡年龄比例70岁以上最高,死因前三位依次为：循环系统疾病、肿瘤、呼吸系统疾病。循环系疾病中,以脑血管病、急性心梗、冠心病死亡率较高。结论：加强对循环系统疾病、恶性肿瘤及呼吸系统疾病的重点防治可能有助于减少本省疾病发病和死亡。     

Decreased circulating miR-375: A potential biomarker for patients with non-small-cell lung cancer

MicroRNAs (miRNAs) are directly involved in cancer initiation, progression and metastasis. Alterations of miRNAs expression in cancer tissue may be reflected in circulation. We attempted to investigate the expression and clinical significance of plasma miR-20a, miR-31 and miR-375 in patients with non-small cell lung cancer (NSCLC). The plasma levels of miR-20a, miR-31 and miR-375 in 164 NSCLC patients and 164 healthy controls (discovery cohort) were evaluated and compared among various clinicopathological characteristics. The relationship between miRNA expression and clinical outcome of NSCLC patients was examined in an independent cohort (53 cases and 53 controls). The expression level of miR-375 in tissue was also examined. Plasma miR-375 levels in NSCLC patients were significantly decreased in both patient cohorts (P < 0.05). In addition, patients with metastatic NSCLC had lower plasma miR-375 expression than those with non-metastatic NSCLC (P < 0.05). Survival analysis showed that patients with low miR-375 expression had worse overall survival rates than those with high miR-375 expression (hazard ratios (HR) = 1.537 (1.046–2.258), P = 0.029). This association was independently validated in a separate cohort of 53 NSCLC patients (HR = 2.406, 95% CI 1.170–4.945, P = 0.017). The expression level of miR-375 was also found to be significantly down-regulated in NSCLC tissues compared with paracancerous tissues (P < 0.001). These findings indicate that miR-375 has an important role in NSCLC initiation and progression, and may be an independent poor prognostic factor in NSCLC patients.     

湖北省纽荷尔脐橙果实品质状况的研究

以纽荷尔脐橙为试材,分析了湖北省13个产地果实的常规品质和果皮色差值。结果显示,不同产地纽荷尔脐橙果实品质差异明显。系统聚类结果表明,秭归县、巴东县和兴山县的常规品质聚为第一类,长阳县、郧县、公安县、枝江市和宜都市聚为第二类,而丹江口市、阳新县、通城县、天门市和京山县聚为第三类;就果皮色差值来看,长阳县、郧县、兴山县和宜都市聚为第一类,巴东县、京山县、枝江市、丹江口市、阳新县、公安县、秭归县聚为第二类,天门市和通城县聚为第三类。综合分析常规品质和果皮色差值可以看出,三峡库区的兴山县、秭归县、巴东县纽荷尔脐橙综合品质最好,邻近三峡库区的长阳县、宜都市、枝江市,丹江库区的郧县和卷桥库区的公安县次之,丹江口市、阳新县、京山县,尤其是天门市和通城县的品质表现不如上述各个产地。因此湖北省纽荷尔脐橙应重点集中在三峡库区这一优势区域内优先发展,同时向其邻近的适宜地区辐射,而在其它产地宜选择小气候适宜地区适当发展。