Phospholipase C from Pseudomonas aeruginosa and Bacillus cereus:characterization of catalytic activity

Objective:To study characteristics of phospholipases C(PLCs),their importance for producing microorganisms us well us the potential of their use for industrial purposes.Methods:PLC from Bacillus cereus(B.cereus) D101 was selected as an example of Gram-positive PLCs and PLC from Pseudomanas aeruginosa(P.aeruginosa) D183 of Gram-negative ones.Enzymes were partially purified by ammonium sulfate precipitation followed by membrane dialysis.Partially purified preparations were used to study effect of different factors on activities as well as in substrate specificity tests which were conducted using a turbidimetric assay method.Results:Maximum activity was at pH 7 and 8 and 40 ℃ for P.aeruginosa PLC,and pH 8-10 and 37 ℃ for B.cereus PLC.Both PLCs were inhibited by Pi at 5 mM or higher,whereas,PLC from B.cereus only was inhibited by EDTA.Activity of P.aeruginosa PLC was not affected by removing Zn~(2+) ions from reaction mixture or their replacement with Ca~(2+),Ba~(2+),Mg~(2+) or Mn~(2+)ions.Vis-a-vis,activity of B.cereus PLC was found to be metal ion dependent PLCs from both isolates were relatively thermostable and showed maximum affinity toward phosphatidylcholine.Sphingomyelin and phosphatidylethanolamine were not good substrates and phosphatidylinositol,phosphatidylserine,phosphatidylglycerol and cardiolipin could be considered nonsubstrates.Conclusions:Human body physiological conditions could favor activity of P.aeruginosa and B.cereus PLCs.These enzymes may participate in phosphate scavenging and virulence of producing isolates but not in autolysis.PLCs from both isolates are potential candidates for industrial use.     

Bt Toxin Modification for Enhanced Efficacy

Insect-specific toxins derived from Bacillus thuringiensis (Bt) provide a valuable resource for pest suppression. Here we review the different strategies that have been employed to enhance toxicity against specific target species including those that have evolved resistance to Bt, or to modify the host range of Bt crystal (Cry) and cytolytic (Cyt) toxins. These strategies include toxin truncation, modification of protease cleavage sites, domain swapping, site-directed mutagenesis, peptide addition, and phage display screens for mutated toxins with enhanced activity. Toxin optimization provides a useful approach to extend the utility of these proteins for suppression of pests that exhibit low susceptibility to native Bt toxins, and to overcome field resistance.     

MDR-selective microbial-based therapy: A novel approach to cancer treatment

Microbial-based therapy of cancer is one of the earliest non-surgical anticancer therapies. The main limitation of such therapies is the toxicity of the therapeutic dose. This article discusses a novel approach that exploits cancer multidrug resistance (MDR) to provide a safer microbial-based therapy. As multidrug resistant cells can only contain limited amounts of a variety of susceptible drugs including certain antibiotics, we can take advantage of MDR to create a micro-environment (antibiotic free) that favors growth of intracellular bacteria within cancer cells. Thus, this approach targets cancer cells and spares normal cells (shielded by antibiotic): providing a more selective thus safer anticancer treatment. This article also explores the potentials of Chlamydia pneumoniae as an anti-cancer agent in this MDR-selective microbial-based therapy: its unique life cycle and the immune response to its infection suggest that it could be used directly, in the proposed approach, without any pre-requirements.     

Stratification of Gallstones in the Gallbladder

A clinical approach to the diagnosis of congenital cardiac malformations is described which the authors have found effective in exposing the important signs and their significance. Each available diagnostic method is evaluated separately before all data are correlated.

Clinical diagnosis based on history, physical examination, roentgenography and electrocardiography was 94 per cent accurate in a series of cases seen in office consultation and 90 per cent accurate in a series of hospital cases reviewed. The significance of the various signs and symptoms that are routinely searched for in the physical examination is discussed.

The salient points in the clinical diagnosis of the common entities are presented.     

枯草杆菌二联活菌颗粒对厌食症患儿血清神经肽Y和肿瘤坏死因子-α水平影响及疗效

目的探讨枯草杆菌二联活菌颗粒对厌食症患儿血清神经肽Y(NPY)和肿瘤坏死因子-α(TNF-α)水平影响及疗效。方法选取2012年6月~2014年6月在浙江省嘉兴市妇幼保健院儿童厌食症患者86例,采用随机数字表将其分为观察组(43例)和对照组(43例)。两组患儿均予以纠正患儿不良饮食习惯、健胃消食药和葡萄糖酸锌等常规治疗。观察组患儿加用枯草杆菌二联活菌颗粒1.0 g/次,2次/d,温开水冲服。疗程为6周。对照组患儿除不使用枯草杆菌二联活菌颗粒外余治疗基本同观察组。观察并记录两组患儿治疗前和治疗6周后血清NPY和TNF-α水平的变化,并比较其治疗后的临床效果及药物不良反应。结果治疗6周后,两组患儿血清NPY和TNF-α水平[观察组:(45.53±7.82)pg/m L,(10.24±2.74)mmol/L;对照组:(37.39±7.53)pg/m L,(8.19±2.13)mmol/L]较治疗前[观察组:(32.17±5.18)pg/m L,(6.82±1.76)mmol/L;对照组:(32.79±4.23)pg/m L,(7.03±1.54)mmol/L]明显上升(t=2.89、3.12、2.31、2.45,P<0.05或P<0.01),且观察组上升程度较对照组更明显(t=2.19、2.24,P<0.05);同时观察组患儿临床总有效率(93.02%)较对照组(76.74%)更佳(χ2=4.44,P<0.05)。两组患儿治疗中无明显的药物不良反应发生。结论枯草杆菌二联活菌颗粒治疗儿童厌食症的效果较确切,且安全性较好,其作用机制可能与其升高血清NPY和TNF-α水平,提高患儿的食欲密切相关。     

地衣芽孢杆菌活菌颗粒杂菌检查方法验证

目的 建立地衣芽孢杆菌活菌颗粒杂菌检查方法。方法 控制菌检查采用平皿涂布法;非致病性杂菌检查以杂菌率不得过0.1%为限度指标,采用营养琼脂平皿涂布法37 ℃培养;真菌计数采用玫瑰红钠琼脂平皿涂布法25 ℃培养。结果 控制菌检查、非致病性杂菌检查和真菌计数方法均满足中国药典2010年版验证试验的基本要求。结论 该方法可作为地衣芽孢杆菌活菌颗粒杂菌检查方法。     

Risk factors for latent tuberculosis infection in children in South Korea

Objectives: In South Korea, latent tuberculosis infection (LTBI) screening is a critical strategy associated with efforts to reduce the incidence of tuberculosis (TB). Currently, only children with a known history of TB contact are considered as pediatric high-risk groups for LTBI, and consequently, LTBI screening is only provided to these children. However, to reduce the incidence of TB, the high-risk groups that undergo LTBI screening should be expanded. This study aimed to assess the risk factors for LTBI among children living in South Korea with no known history of TB contact for the identification of additional high-risk groups. We investigated the risk factors for LTBI among US visa applicant children, who undergo LTBI screening regardless of their TB contact history.

Methods: We obtained data on demographic characteristics, medical history, Bacillus Calmette–Guerin (BCG) vaccination history, and results of LTBI screening for children aged 2–14 years. A tuberculin skin test was used for the diagnosis of LTBI, and an induration of 10 mm or greater was used to define a positive test. Adjusted odds ratios and 95% confidence intervals were calculated to determine the association between clinical and demographic variables and LTBI.

Results: Of the 1,664 study participants, 91 (5.5%) had LTBI. The binary logistic regression analysis showed that children born in high TB burden foreign countries had the highest odds of LTBI when considering all the risk factors investigated. Increasing age, absence of BCG vaccination, and a previous diagnosis of asthma were also significant risk factors for LTBI.

Conclusion: These results indicate that children born in high TB burden foreign countries should be considered a high-risk group for LTBI in South Korea; the inclusion of these children in LTBI screening should be considered.     

海洋细菌Bacillus coagulans spp.heishijiaosis 发酵液抗真菌活性及其机制研究

目的对凝结芽胞杆菌黑石礁新亚种LU-B02产生的抗白色念珠菌活性物质的作用靶位及抑菌谱进行了研究。方法采用山梨醇保护形态变异法结合扫描电镜超微结构观察研究了活性物质的作用靶位,最小抑菌浓度(MIC)法比较了该菌发酵液对不同真菌的抑菌活性。结果该活性物质抑制白色念珠菌细胞壁中的主要组分——葡聚糖的合成从而造成其细胞壁残缺。该活性物质具有抗真菌专一性,对革兰氏阳性代表菌金黄色葡萄球菌和革兰氏阴性代表菌大肠杆菌等细菌均无抑制效果,而对人体病原真菌抑菌效果较为明显,尤其是对白色念珠菌的抑制效果较好。MIC测定表明白色念珠菌对LU-B02活性物质高度敏感,相当于斯皮仁诺8~16μg,抑菌效价每毫升相当于3 500 U制霉菌素或洁尔阴活性的4倍。发酵液在酸性条件下加入0.2%冰片时,室温下存放6个月仍可保持良好的抗白色念珠菌活性。结论凝结芽孢杆菌黑石礁新亚种(Bacillus coagulans spp.heishijiaosis)产生的活性物质在控制以白色念珠菌为主的真菌感染方面具有良好应用前景。     

产纤溶酶海洋枯草芽孢菌的液体发酵条件优化

目的采用响应面法对高产纤溶酶海洋菌株Y-6-A的液体发酵条件进行优化,以进一步提高产酶量并考察该法的有效性。方法先采用单因素实验考查各因素对菌株产酶的影响,并在此基础上利用PlackettBurman设计筛选到影响菌株产酶的主要因素,接着通过最陡爬坡实验逼近酶活最高区域,最后根据Box-Behnken中心组合实验设计对各显著因子进行优化。结果最终得到影响产酶的因素有4个:可溶性淀粉、黄豆粕粉、温度和转速,最佳发酵条件为:可溶性淀粉46.1g/L,黄豆粕粉23.3g/L,温度31.2℃,转速184r·min^-1,在此发酵条件下得到的酶活为3 606.23IU/mL,经3次验证实验测得的酶活稳定在3 580.32±14.82IU/mL,较优化前提高了22.4%,此外,实验值与预测值之间的相对误差为0.63%。结论响应面的优化结果比较理想,经优化后能较好提高酶活。