The Contribution of Crab Burrow Excavation to Carbon Availability in Surficial Salt-marsh Sediments

Geomorphology, vegetation and tidal fluxes are usually identified as the factors introducing variation in the flushing of particulate organic matter (POM) from tidal marshes to adjacent waters. Such variables may, however, be insufficient to explain export characteristics in marshes inhabited by ecosystem engineers that can alter the quantity and quality of POM on the marsh surface that is subject to tidal flushing. In this study we evaluated the balance between transfer of buried sedimentary organic carbon (C) to the marsh surface due to crab excavation (measured from the mounds of sediment excavated from burrows) and outputs of C from the surface due to sediment deposition within crab burrows (estimated from sediment deposited within PVC burrow mimics), in a Southwestern Atlantic salt marsh supporting dense (approximately 70 ind m⁻²) populations of the crab Chasmagnathus granulatus. C excavation by crabs was much greater than deposition of C within crab burrow mimics. Per area unit estimates of the balance between these two processes indicated that crabs excavated 5.98 g m⁻² d⁻¹ and 4.80 mg m⁻² d⁻¹ of total and readily (10 d) labile C, respectively. However, sediments excavated by crabs showed a significantly lower content of both total and readily-labile C than sediment collected in burrow mimics. This indicates that ecosystem engineering by burrowing crabs causes a net decrease in the concentration of C in the superficial sediment layers and, thus, an overall decrease in the amount of C that can be washed out of the marsh by tidal action. Incorporating the in situ activities of ecosystem engineers in models of marsh export should enhance understanding of the function of marshes in estuarine ecosystems.     

哌拉西林/他唑巴坦对三种非发酵菌体外敏感性检测方法的比较

目的评价不同方法检测无CLSI解释标准的3种非发酵菌———嗜麦芽窄食单胞菌、洋葱伯克霍尔德菌、脑膜脓毒性黄杆菌对哌拉西林/他唑巴坦的耐药性情况,以利于检测方法的选择应用。方法同时用标准K-B法、VITEK-32配套的药敏检测卡GNS-143法、E-test试条法检测临床分离的139株无CLSI解释标准的非发酵菌对哌拉西林/他唑巴坦的敏感性,并对3种方法相互间的符合情况进行比较。结果3种方法检测80株嗜麦芽窄食单胞菌,36株洋葱伯克霍尔德菌,23株脑膜脓毒性黄杆菌对哌拉西林/他唑巴坦的敏感率分别为:46.3%、82.5%、45.0%,77.8%、44.4%、52.8%,69.6%、52.2%、56.5%;耐药率分别为:32.5%、10.0%、48.8%,19.4%、38.9%、38.9%,17.4%、39.1%、21.7%。139株细菌3种方法间的符合情况:K-B法与VITEK法比较,完全符合率为51.1%、部分符合率为22.3%、完全不符合率为26.6%;K-B法与E-test试条法比较,三者分别为61.9%、15.8%、22.3%;VITEK法与E-test试条法比较,三者分别为56.1%、16.6%、27.3%。结论不同的方法检测同一种细菌对哌拉西林/他唑巴坦的药敏结果有较大不同,各方法间的可比性较差。嗜麦芽窄食单胞菌K-B法与E-test试条法符合性好于VITEK法,而其他2种细菌VITEK法好于K-B法。建议临床实验室对此类细菌的药敏检测仅报告实验检测结果,而不报药敏检测解释结果。     

应用正交试验探讨抗—HBs含量测定（EIA）的影响因素

本文报道了应用正交试验研究抗－ＨＢｓ 含量测定（ＥＩＡ）的影响因素,并找出了较佳的试验条件。培育时间和显色剂是影响该试验的主要因素。加样品５０ μｌ,酶联试剂５０ μｌ,显色剂Ａ、Ｂ各１００ μｌ,２５℃分别培育３０ ｍ ｉｎ、１５ ｍ ｉｎ。为较优的试验条件。     

基因组水平的基因挖掘与功能分析方法的探讨

为了实现基因组中特定基因功能的注释,研究者提出一种新的思路,即利用对目的基因启动子上游的顺式元件的功能的分析,进一步来推断目的基因的功能。在此主要对基因组水平的基因挖掘与功能分析方法及其研究进展进行了探讨。     

TCT、HPV检测在宫颈锥切术后复发中的预测价值

目的:评估薄层液基细胞学检查(thinprep cytologic test,TCT)和人乳头瘤病毒(human papillomavirus,HPV)检测在宫颈锥切术后复发中的预测价值。方法:随访531例病理诊断为子宫颈上皮内瘤变(cervical intraepithelial neoplasia,CIN)Ⅱ-Ⅲ级接受宫颈锥切术的患者,分别于术后3、6个月及术后每6-12月随访1次,以TCT及HPV检测作为随访的检测指标,若二者有一项异常,行阴道镜下活组织检查,病理证实存在子颈上皮内瘤变Ⅰ-Ⅲ级者视为复发。采用敏感度、特异度、阳性预测值、阴性预测值表示TCT、HPV检测性能。结果:531例患者中10%(54例)的患者出现不同级别的病变复发。TCT在术后预测病变复发的灵敏度77%,特异度72%;HPV在术后预测病变复发的灵敏度95%,特异度60%,TCT联合HPV预测病变复发的灵敏度100%,特异性80%。术后HPV负荷量100 RLU/PC者较HPV负荷量100 RLU/PC者而言术后病变复发的风险增高,差别有统计学意义(P0.01),术后HPV负荷量100 RLU/PC是锥切术后病变复发的高危因素。结论:使用细胞学联合HPV检测是有效的预测宫颈锥切术后病变复发的方法,术后高HPV负荷量与病变复发相关,并可对术后复发高风险人群进行分流,临床需严密随访。     

Conventional methods and future trends in antimicrobial susceptibility testing

Antimicrobial susceptibility testing is an essential task for selecting appropriate antimicrobial agents to treat infectious diseases. Constant evolution has been observed in methods used in the diagnostic microbiology laboratories. Disc diffusion or broth microdilution are classical and conventional phenotypic methods with long turnaround time and labour-intensive but still widely practiced as gold-standard. Scientists are striving to develop innovative, novel and faster methods of antimicrobial susceptibility testing to be applicable for routine microbiological laboratory practice and research. To meet the requirements, there is an increasing trend towards automation, genotypic and micro/nano technology-based innovations. Automation in detection systems and integration of computers for online data analysis and data sharing are giant leaps towards versatile nature of automated methods currently in use. Genotypic methods detect a specific genetic marker associated with resistant phenotypes using molecular amplification techniques and genome sequencing. Microfluidics and microdroplets are recent addition in the continuous advancement of methods that show great promises with regards to safety and speed and have the prospect to identify and monitor resistance mechanisms. Although genotypic and microfluidics methods have many exciting features, however, their applications into routine clinical laboratory practice warrant extensive validation. The main impetus behind the evolution of methods in antimicrobial susceptibility testing is to shorten the overall turnaround time in obtaining the results and to enhance the ease of sample processing. This comprehensive narrative review summarises major conventional phenotypic methods and automated systems currently in use, and highlights principles of some of the emerging genotypic and micro/nanotechnology-based methods in antimicrobial susceptibility testing.     

On Approximate and Exact Sample Sizes of Equivalence Tests for Binomial Proportions

There exist several formulae for sample sizes for testing the equivalence of binomial proportions which are based on approximations by the normal distribution. Quite often these formulae produce drastically different results. In this paper the validity of the approximate sample sizes is investigated with respect to the exact distributions.