2019-2020年宁夏炭疽芽胞杆菌毒力鉴定及基因分型研究

目的 了解宁夏2019-2020年分离的炭疽芽胞杆菌菌株致病力及基因分型特征,为宁夏皮肤炭疽疫情判定与分子溯源提供实验室依据。方法 收集2019-2020年宁夏各地区分离的炭疽芽胞杆菌,对其进行毒力鉴定,并运用MLVA-15和canSNP分型技术进行基因分型研究。结果 2019-2020年宁夏分离到的炭疽芽胞杆菌均为强毒株,MLVA-15分型为同一种群,canSNP分型为A.Br.001/002组。结论 2019-2020年宁夏分离到的炭疽芽胞杆菌致病力较强,且菌株呈现相同的基因分型特征,提示菌株间存在流行病学关联。此研究结果填补了宁夏炭疽芽胞杆菌实验室检测中菌株致病力及基因分型的空白。     

双歧杆菌完整肽聚糖对汉坦病毒核蛋白诱导细胞免疫应答的影响

目的探讨双歧杆菌完整肽聚糖作为佐剂对汉坦病毒核蛋白(HTNV-NP)诱导细胞免疫应答的影响。方法提取双歧杆菌完整肽聚糖(WPG),并将其与HTNV-NP混合后免疫BALB/c小鼠。于加强免疫后4周,检测小鼠NK细胞和CTL的杀伤活性、淋巴细胞增殖反应,采用ELISA法检测IL-2和IFN-γ分泌水平,同时观察WPG的安全性。结果注射HTNV-NP组和注射HTNV-NP+WPG组小鼠NK细胞活性、CTL细胞毒活性、淋巴细胞增殖反应刺激指数(SI)以及IL-2、IFN-γ的分泌水平分别为(5.16±1.34)%(、28.46±4.16)%、1.7(、89.65±7.63)pg/ml(、245.68±56.74)pg/ml和(9.85±0.87)%(、43.29±5.54)%、3.1、(204.48±36.17)pg/ml、(473.29±74.94)pg/ml,差异有显著性(P<0.01)。其间小鼠未出现明显不良反应。结论WPG可显著增强HTNV-NP的细胞免疫应答,是良好的疫苗佐剂。     

Just an additional hydrogen bond can dramatically reduce the catalytic activity of Bacillus subtilis lipase A I12T mutant: An integration of computational modeling and experimental analysis

Understanding the structural basis and energetic property of hydrogen bonding and its effects on enzymatic activity is fundamentally important for the rational design of specific enzymes with desired biological functions. In the current study, site-directed mutagenesis analysis preliminarily revealed that the amino acid substitution of Ile12 with Thr12 (I12T) dramatically reduced the hydrolytic activity of Bacillus subtilis lipase A. A further computational investigation proposed that the I12T mutation would establish a geometrically perfect hydrogen bond between the mutated Thr12 and catalytic Ser77 of lipase A, which considerably impaired the catalytic capability of lipase A through two distinct but complementary approaches: rigidizing the enzyme active site and lowering the nucleophilic ability of the catalytic residue Ser77. To verify this hypothesis, a homogenous mutation I12S serving as the control to the I12T mutation was created to examine the hydrogen bonding effect on enzymatic activity. It was found that the I12S mutant only suffered from a slight damage in its hydrolytic ability due to absence of the hydrogen bond originally present at the Thr12–Ser77 interface in the I12T mutant, which was further characterized systematically by quantum mechanics/molecular mechanics (QM/MM) modeling, atom-in-molecules (AIM) analysis and molecular dynamics (MD) simulation. It is suggested that the hydrogen bond arising from the I12T mutation in lipase A can considerably reduce the flexibility and mobility of the enzyme active site, thus impairing the catalytic activity of the lipase A I12T mutant remarkably; the activity loss can be, however, largely recovered by replacing Thr residue at the 12th position of I12T mutant with its analog Ser, which is chemically similar to Thr but cannot form effective hydrogen bonding with Ser77.     

Specificity of tuberculin skin test improved by BCG immunization schedule change in Japan

IntroductionTuberculin skin test (TST) has been used to diagnose tuberculosis (TB) and latent tuberculosis infection (LTBI). However, in Bacillus Calmette-Guérin (BCG) vaccinated patients, TST tends to produce false-positive results. According to the previous vaccination schedule, Japanese people were mandated to receive up to three doses of BCG-vaccine. The vaccination schedule was changed in 2003 and as per the new schedule, only infants are administered a dose of BCG vaccine. Our hypothesis is that this change can lead to a reduction in the cross-reaction to TST.MethodsWe evaluated the TST results obtained from 1097 recruits from six defense camps and 667 recruits from an air base. These TST data were divided into two groups according to the date of birth: a new group and an old group according to the BCG immunization schedule. We then analyzed positive and negative reaction of TST and erythema sizes.ResultsWe confirmed that the change in BCG-vaccination schedule significantly decreased TST false-positive reaction (P_meta = 1.4 × 10⁻¹⁸; risk ratio = 0.83; 95% confidence interval: 0.80–0.87) and erythema size (P_meta = 1.1 × 10⁻⁴; mean difference = 6.6 mm; 95% confidence interval: 3.2 mm–9.9 mm).ConclusionsWe showed the reduction in BCG cross-reaction to TST, in the new BCG vaccination schedule group, compared to the old group, we also have extracted information on the improvement in the specificity of TST for LTBI and TB diagnosis, which resulted from BCG schedule change.     

The IL‐23/Th17 axis is involved in the adaptive immune response to Bacillus anthracis in humans

The neutralization of toxins is considered essential for protection against lethal infection with Bacillus anthracis (BA), a select agent and bioterrorism threat. However, toxin‐neutralizing activity alone would not be expected to provide sterile immunity. Therefore, we hypothesized that the development of an adaptive immune response against BA is required for bacterial clearance. We found that human monocyte‐derived dendritic cells (hDCs) kill germinated BA bacilli, but not nongerminated BA spores. hDCs produce IL‐1β, IL‐6, IL‐12, and IL‐23, and these cytokines are differentially regulated by germination‐proficient versus germination‐deficient BA spores. Moreover, the IL‐23 response to BA spores is regulated by IL‐1R‐mediated signaling. hDCs infected with germinating BA spores stimulated autologous CD4⁺ T cells to secrete IL‐17A and IFN‐γ in a contact‐dependent and antigen‐specific manner. The T‐cell response to BA spores was not recapitulated by hDCs infected with germination‐deficient BA spores, implying that the germination of spores into replicating bacilli triggers the proinflammatory cytokine response in hDCs. Our results provide primary evidence that hDCs can generate a BA‐specific Th17 response, and help elucidate the mechanisms involved. These novel findings suggest that the IL‐23/Th17 axis is involved in the immune response to anthrax in humans.     

Efficacy of Peracetic Acid in Rapid Disinfection of Resilon and Gutta-percha Cones Compared with Sodium Hypochlorite,Chlorhexidine, and Povidone-iodine

Background

The aim of this investigation was to compare the effectiveness of 3% sodium hypochlorite (NaOCl), 2% chlorhexidine, 1% peracetic acid, and 10% povidone-iodine in the rapid disinfection of Resilon (Pentron Clinical Technologies, LLC, Wallingford, CT) and gutta-percha cones contaminated with Enterococcus faecalis and Bacillus subtilis.

Methods

Two hundred fifty-six samples consisting of 128 gutta-percha cones and 128 Resilon cones were used in this study. The materials were tested for disinfection according to the type of solution (3% NaOCl, 2% chlorhexidine, 1% peracetic acid, or 10% povidone-iodine), the time of exposure to each solution (1 or 5 minutes), and the type of microorganisms (E. faecalis or B. subtilis). Subsequent to the disinfection, samples were placed in test tubes containing 10 mL Mueller-Hinton broth and incubated at 37°C for 7 days. All test tubes were observed at 24-hour intervals and visually checked for turbidity, signifying microbial growth.

Results

In this study, 1% peracetic acid showed the best results for both 1 minute and 5 minutes of disinfection, 2% chlorhexidine showed the second best results although it was statistically at par with peracetic acid, and 3% hypochlorite ranked third in disinfection; this was statistically significant when compared with peracetic acid and chlorhexidine. Disinfection by povidone-iodine was the least within all the groups for both contact times although disinfection for 5 minutes showed better results than disinfection for 1 minute for gutta-percha.

Conclusions

The outcome of this study confirmed the efficacy of 1% peracetic acid and 2% chlorhexidine in the rapid disinfection of both Resilon and gutta-percha.     

Probiotic Therapy Reduces Periodontal Tissue Destruction and Improves the Intestinal Morphology in Rats With Ligature‐Induced Periodontitis

Background: With increase in the incidence of resistance to antibiotics, probiotics are emerging as a promising adjunctive periodontal therapy. The authors of this study evaluate the influence of probiotic (PROB) supplementation on ligature‐induced periodontitis (LIP) and intestinal morphology in rats. Methods: Thirty‐two rats were randomly divided into four groups: control (C), LIP, PROB, and LIP/PROB. In groups PROB and LIP/PROB, the PROB was administered orally by addition to the drinking water of the animals for 44 days. In groups LIP and LIP/PROB, the mandibular right first molar of the animals received a cotton ligature that was left in the same position for 14 days. All animals were euthanized 44 days after the start of the PROB supplementation. The jaws were resected and histomorphometric analyses were performed. The measurements included evaluation of attachment loss (AL) and alveolar bone level (ABL) on the distal root of the mandibular first molar. Samples of the duodenum, jejunum, and ileum were also dissected from each animal to evaluate the villous height (VH) and crypt depth (CD). The data obtained were subjected to statistical analyses (analysis of variance, Tukey; P <0.05). Results: Mean values of AL and ABL were significantly higher in group LIP compared with group LIP/PROB (AL: 3.05 ± 0.57 mm and 1.78 ± 0.63 mm, respectively; ABL: 4.21 ± 0.42 mm and 3.38 ± 0.17 mm, respectively). In group LIP/PROB, the mean values of VH and CD of the jejunum were significantly higher than the ones from group LIP (VH: 672.1 ± 83.3 µm and 528.0 ± 51.7 µm, respectively; CD: 463.8 ± 100.9 µm and 269.0 ± 48.4 µm, respectively). Conclusions: It can be concluded that PROB supplementation 1) reduces AL and alveolar bone loss in rats with LIP and 2) can protect the small intestine from reactive changes induced by LIP.     

ICUD-EAU International Consultation on Bladder Cancer 2012: Non–Muscle-Invasive Urothelial Carcinoma of the Bladder

Context

Our aim was to present a summary of the Second International Consultation on Bladder Cancer recommendations on the diagnosis and treatment options for non–muscle-invasive urothelial cancer of the bladder (NMIBC) using an evidence-based approach.

Objective

To critically review the recent data on the management of NMIBC to arrive at a general consensus.

Evidence acquisition

A detailed Medline analysis was performed for original articles addressing the treatment of NMIBC with regard to diagnosis, surgery, intravesical chemotherapy, and follow-up. Proceedings from the last 5 yr of major conferences were also searched.

Evidence synthesis

The major findings are presented in an evidence-based fashion. We analyzed large retrospective and prospective studies.

Conclusions

Urothelial cancer of the bladder staged Ta, T1, and carcinoma in situ (CIS), also indicated as NMIBC, poses greatly varying but uniformly demanding challenges to urologic care. On the one hand, the high recurrence rate and low progression rate with Ta low-grade demand risk-adapted treatment and surveillance to provide thorough care while minimizing treatment-related burden. On the other hand, the propensity of Ta high-grade, T1, and CIS to progress demands intense care and timely consideration of radical cystectomy.