Morphological and physical characterization of the capsular layer of Vibrio cholerae O139

The morphological and physical characteristics of the capsule of Vibrio cholerae O139 were examined. An electron microscopic study using the freeze-substitution technique showed that all of the V. cholerae strains of the O139 serogroup examined have a very thin fibrous layer on the outside of the outer membrane. In contrast, the mutants of strain O139, strain MO10T4 (which lacks capsule synthesis), and strain Bengal-2R1 (which fails to synthesize both the capsule and the O-antigen of lipopolysaccharide) were all found to have lost the surface layer. In addition, the capsule layer could also not be observed on the surface of V. cholerae strain O1. To determine the biological characteristics of the capsule of strains of the O139 serogroup, we investigated the serum killing activity and bacterial phagocytosis by polymorphonuclear leukocytes. The O139 strains were more resistant to the serum killing activity than were the V. cholerae O1 strain and the O139 mutant strains, thus suggesting that the existence of the capsule gave a serum-resistant character to the O139 strains. The surface character of the O139 strains had the same hydrophobic character as did that of the O139 mutant strains and the O1 strain. In addition, all the V. cholerae O1 and O139 strains examined, including the mutant strains, were effectively ingested by the human polymorphonuclear leukocytes. The number of ingested bacteria was not significantly different among the strains, and the ingestion of the acapsular O139 mutants thus showed that the capsule does not play an antiphagocytic role. These data suggest that the capsule of V. cholerae O139 has a physiological function different from that of the ordinal hydrophilic capsule that is found in invasive bacteria such as Klebsiella pneumoniae. Received: 23 March 1998 / Accepted: 28 July 1998     

Biochemistry and structure of the glycan secreted by desiccation-tolerantNostoc commune (Cyanobacteria)

Summary Filaments of the desiccation-tolerant cyanobacteriumNostoc commune are embedded within, and distributed throughout, a dense glycan sheath. Analysis of the glycan of field materials and of pure cultures ofN. commune DRH 1 through light and electron microscopy, immunogold labelling and staining with dyes, revealed changes in the pattern of differentiation in glycan micro-structure, as well as localized shifts in pH, upon rehydration of desiccated field material. A Ca/Si rich external (pellicular) layer of the glycan acts as a physical barrier to epiphytic bacteria on the surface ofN. commune colonies. A purified fraction (>12 kDa) of an aqueous extract of the glycan from desiccated field material contained glucose, N-acetylglucosamine, glucosamine, mannose, and galactosamine with ratios of 3.11.410.10.06, respectively. Lipid soluble extracts ofN. commune contained trehalose and sucrose and the levels of both became undetectable following cell rehydration. Intracellular cyanobacterial trehalase was identified using immunoblotting and its synthesis was detected upon rehydration of desiccated field cultures. Elemental analysis of glycan extracts showed a flux in the concentrations of salts in the glycan matrix following rehydration of desiccated colonies. Water-stress proteins (Wsp; most abundant proteins in glycan), a water soluble UV-A/B-absorbing pigment, the lipid-soluble UV-protective pigment scytonemin (in both its oxidized and reduced forms), as well as two unidentified cyanobacterial glycoproteins (75 kDa and 110 kDa), were found within the glycan matrix. An unidentified 68 kDa protein, the second most abundant protein in aqueous extracts of the glycan, was isolated and its N-terminal sequence was determined as AFIFGTISPNNLSGTSGNSGIVGSA. Gene bank searches with this sequence identified significant homologies (35–45%) with various carbohydrate-modifying enzymes. The role of the glycan in the desiccation tolerance ofN. commune is discussed with respect to structure/function relationships.Abbreviations EPS extracellular polysaccharides - Wsp water-stress protein - SEM scanning electron microscopy - TEM transmission electron microscopy - EDX energy dispersive X-ray analysis - FPLC fast performance liquid chromatography - SDS-PAGE sodium dodecylsulfate polyacrylamide gel electrophoresis - TLC thin layer chromatography - UV ultra-violet radiation - UTEX University of Texas Culture Collection     

Adherence to human small intestines of capsulated Vibrio cholerae O139

Abstract Capsulated cells of V. cholerae O139 adhered to formalis-fixed or native mucosa of the small intestines from an adult and a child. The primary adherence target was mucus. Capsulated O139 cells adhered better to the antigen sampling cells (M cells) of ileal Peyer's patch than to the absorptive cells. O139 cells on the mucosa appeared as small aggregates. Similar organisms were found on the mucosa of duodenal biopsy samples from patients infected with V. cholerae O139. The findings indicated that capsulated cells of V. cholerae O139 tend to autoagglutinate and contribute to the effective adherence to the intestinal mucosa.     

Isolation and characterization of enterotoxigenic Escherichia coli mutants that produce abnormal heat-labile enterotoxins

Abstract Bacteroides fragilis populations were separated according to the size of surface structure. Subculture of the separated populations produced cultures enriched for 3 different structures; a large capsule, a small capsule and an electron-dense layer (EDL). The ability of these subpopulations to haemagglutinate (HA) erythrocytes from a number of species was examined. Populations which produced either a large or s small capsule did not have HA activity, whereas those with an extracellular EDL did. By mixing populations with EDL and those with either the large or small capsule, the degree of HA could be altered. HA was dependent on the proportion of EDL-bearing bacteria present. Fimbriae were not observed on electron microscopy.     

Induction of opsonic antibodies to the gamma-D-glutamic acid capsule of Bacillus anthracis by immunization with a synthetic peptide-carrier protein conjugate

The capsule of Bacillus anthracis, a polymer of gamma-D-glutamic acid, functions as a virulence determinant and is a poor immunogen. In this study we show that antibodies reactive with the B. anthracis capsule can be elicited in mice by immunization with a conjugate consisting of a synthetic gamma-D-glutamic acid nonamer peptide (gamma-D-glu9) covalently coupled to keyhole limpet hemocyanin. The serum response to gamma-D-glu9 was comprised primarily of IgG antibodies that recognized an epitope requiring a minimum of four gamma-linked D-glutamic acid residues. Antibodies to (gamma-D-glu9) bound to the surface of encapsulated B. anthracis cells and mediated opsonophagoctosis. These findings suggest that anti-capsular antibodies could mediate the clearance of vegetative B. anthracis cells in vivo. Thus, inclusion of an immunogenic capsular component as well as protective antigen in new anthrax vaccines would generate immune responses targeting both the bacteremic and toxigenic aspects of anthrax infection and thus may increase protective efficacy.     

Discrimination of normal gastric mucosa from Helicobacter pylori gastritis using standard endoscopes and a single observation site: studies in children and young adults

Background. In the Helicobacter pylori‐negative normal stomach, collecting venules are visible in the gastric corpus as numerous minute points. This finding has been termed ‘regular arrangement of collecting venules’ (RAC). The aim of the present study was to investigate the reliability of the presence of the RAC pattern for discrimination of normal gastric mucosa from H. pylori gastritis in pediatric patients. Methods. Fifty‐two consecutive children, adolescents and young adults (male:female 24 : 28; median age 15 years, range 8–29 years) referred for endoscopy and assessed for H. pylori infection were prospectively studied. The lower lesser curvature of the corpus near the incisura was evaluated for the RAC pattern using a standard endoscope with the tip close to, but not in contact with, the gastric surface. Gastric biopsies were taken after the endoscopic observation. Results. In all the 29 RAC‐positive patients, active H. pylori gastritis was absent, whereas H. pylori gastritis was found in 20 of 23 RAC‐negative patients (86.9%). Conclusions. Identification of the RAC pattern at the lower lesser curvature of the corpus using close observation with a standard endoscope proved to be an effective and practical marker to discriminate normal histology from H. pylori gastritis among both children and young adults. Absence of the RAC pattern should prompt gastric mucosal biopsies despite otherwise normal‐appearing gastric mucosa.     

Soybean Curd Refuse Alleviates Experimental Tumorigenesis in Rat Colon

Adult Fischer-344 rats which underwent administration of azoxymethane were fed diets containing soybean curd refuse (SCR) or a high-molecular-weight fraction of soy protein digest (HMF), or Hammarsten casein (CAS) as a protein source over a period of 34 weeks. All the living rats of each group at 22, 28 or 34 weeks were endoscopically inspected for tumor incidence in the colon. SCR turned out to be comparable to HMF in anti-tumorigenicity, or rather better than HMF.     

Diffuse reflectance spectroscopy in Barrett’s Esophagus: developing a large field‐of‐view screening method discriminating dysplasia from metaplasia

We evaluated diffuse reflectance spectroscopy implemented as a small field‐of‐view technique for discrimination of dysplasia from metaplasia in Barrett’s esophagus as an adjuvant to autofluorescence endoscopy. Using linear discriminant analysis on 2579 spectra measured in 54 patients identified an optimum a 4‐wavelength classifier (at 485, 513, 598 and 629 nm). Sensitivity and specificity for a test data set were 0.67 and 0.85, respectively. Spectroscopic results show that this technique could be implemented in wide‐field imaging mode to improve the accuracy of existing endoscopy techniques for finding early pre‐malignant lesions in Barrett’s esophagus. Results show that the discrimination occurs likely due to redistribution of blood content in the tissue sensed by the optical probing with the wavelength‐dependent sampling depth. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

电针腧穴联合当飞利肝宁治疗非酒精性脂肪性肝炎的临床研究

目的:探讨电针腧穴联合当飞利肝宁治疗非酒精性脂肪性肝炎(nonalcohlic steatohepatitis,NASH)的临床疗效及其安全性。方法:选择符合2010年非酒精性脂肪性肝病诊疗指南[1]诊断标准的80例非酒精性脂肪性肝炎患者,随机分为联合组(电针联合当飞利肝宁治疗组)和对照组(护肝宁治疗组)各40例,两组患者均在纠正不良生活方式、控制饮食(BMI24)、适量有氧运动等的基础上给予相应的治疗,对照组仅服用护肝宁,3次/d,联合组服用当飞利肝宁及电针腧穴治疗。观察和比较两组的疗效、血清转氨酶、血脂水平、脂肪肝程度变化和不良反应的发生情况。结果:联合组和对照组的治疗总有效率分别为90.0%和62.5%,两组总有效率比较有显著性差异(P0.05)。治疗后,联合组患者的血清转氨酶、血脂水平均较对照组显著降低(P0.05)。治疗中两组均未发现明显不良反应。结论:电针腧穴联合当飞利肝宁对非酒精性脂肪性肝炎有较好的治疗效果,具有很高的临床应用价值。     

NBI及AFE在喉癌早期诊断中的应用

研究表明,喉癌的早期诊断、及时治疗不仅可以提高治愈率,而且也减少了患者的手术创伤和经济负担。积极开展喉癌的早期诊断研究具有重要的临床和社会意义。发现早期喉癌常规方法主要有电子喉镜、纤维喉镜、颈部CT及MRI检查,但并不能明显有效提高早期诊断率。而窄带成像(narrow band imaging,NBI)及自体荧光内镜(autofluorescence endoscopy AFE)是近几年用于喉癌早期诊断的两种新颖的内镜技术。NBI是一种通过变窄光波的波长,使粘膜上皮内乳头样毛细血管袢及粘膜下静脉的结构形成鲜明的对比,从而提高组织表面细微结构的对比度,便于发现病灶。而AFE技术是一种利用自发荧光聚集于病变组织的某个区域产生的差异强度,来区别正常组织与肿瘤性病变,从而用于肿瘤的早期诊断及识别癌前病变。因此,对NBI及AFE的进一步研究及认识对喉癌早期诊断提供非常重要的临床应用价值。