Phylogenetic analysis and identification of different serovars of Mycobacterium intracellulare at the molecular level

Comparative 16S rRNA sequencing was used to infer the phylogenetic relationship among different serovars of the Mycobacterium avium-M. intracellulare complex as well as to define signature nucleotides characteristic for different serovars. In general, the groups defined by rRNA sequencing reflect the classification obtained with sensitin tests and pathogenicity examinations in chickens. Unique 16S rRNA sequence patterns could be defined for (1) M. avium, (2) M. intracellulare serovars 4, 5, 6, 8, 9, 10 and 11, (3) M. intracellulare serovars 12, 13, 14, 15, 17, 19 and 20, (4) M. intracellulare serovar 7 and (5) M. intracellulare serovar 18. Phylogenetically, groups 1 and 2 on one hand and groups 3, 4 and 5 on the other hand each share a common ancestor. M. paratuberculosis was indistinguishable from M. intracellulare serovars 4, 5, 6, 8, 9, 10 and 11 by this kind of analysis.     

Evidence That Transition from Health to Psychotic Disorder Can Be Traced to Semi-Ubiquitous Environmental Effects Operating against Background Genetic Risk

Background

In order to assess the importance of environmental and genetic risk on transition from health to psychotic disorder, a prospective study of individuals at average (n = 462) and high genetic risk (n = 810) was conducted.

Method

A three-year cohort study examined the rate of transition to psychotic disorder. Binary measures indexing environmental exposure (combining urban birth, cannabis use, ethnicity and childhood trauma) and proxy genetic risk (high-risk sibling status) were used to model transition.

Results

The majority of high-risk siblings (68%) and healthy comparison subjects (60%) had been exposed to one or more environmental risks. The risk of transition in siblings (n = 9, 1.1%) was higher than the risk in healthy comparison subjects (n = 2, 0.4%; OR_adj  = 2.2,95%CI:5–10.3). All transitions (100%) were associated with environmental exposure, compared to 65% of non-transitions (p = 0.014), with the greatest effects for childhood trauma (OR_adj  = 34.4,95%CI:4.4–267.4), cannabis use (OR = 4.1,95%CI:1.1, 15.4), minority ethnic group (OR = 3.8,95%CI:1.2,12.8) and urban birth (OR = 3.7,95%CI:0.9,15.4). The proportion of transitions in the population attributable to environmental and genetic risk ranged from 28% for minority ethnic group, 45% for urban birth, 57% for cannabis use, 86% for childhood trauma, and 50% for high-risk sibling status. Nine out of 11 transitions (82%) were exposed to both genetic and environmental risk, compared to only 43% of non-transitions (p = 0.03).

Conclusion

Environmental risk associated with transition to psychotic disorder is semi-ubiquitous regardless of genetic high risk status. Careful prospective documentation suggests most transitions can be attributed to powerful environmental effects that become detectable when analysed against elevated background genetic risk, indicating gene-environment interaction.     

Identification of a Novel Genomic Island Specific to Hospital-Acquired Clonal Complex 17 Enterococcus faecium Isolates

Hospital-acquired clonal complex 17 (CC17) Enterococcus faecium strains are genetically distinct from indigenous strains and are enriched with resistance genes and virulence genes. We identified a genomic island in CC17 E. faecium tentatively encoding a metabolic pathway involved in carbohydrate transport and metabolism, which may provide a competitive advantage over the indigenous E. faecium microbiota.     

Enterococcal surface protein Esp is not essential for cell adhesion and intestinal colonization of Enterococcus faecium in mice

Background  

Enterococcus faecium has globally emerged as a cause of hospital-acquired infections with high colonization rates in hospitalized patients. The enterococcal surface protein Esp, identified as a potential virulence factor, is specifically linked to nosocomial clonal lineages that are genetically distinct from indigenous E. faecium strains. To investigate whether Esp facilitates bacterial adherence and intestinal colonization of E. faecium, we used human colorectal adenocarcinoma cells (Caco-2 cells) and an experimental colonization model in mice.     

99mTc-CD19 monoclonal antibody is not useful for imaging of B cell non-Hodgkin’s lymphoma

 In this study we investigated the applicability of ^99mTc-labeled CD19 monoclonal antibody (mAb) for tumor imaging in patients with B cell non-Hodgkin’s lymphoma. A 1-mg sample of murine CD19 mAb was labeled with approximately 550 MBq [^99mTc]pertechnetate. The labeled mAb was administered i. v. to seven patients, four without and three with pretreatment with 10 mg unlabeled CD19 mAb. The number of circulating B cells was decreased by 44±5% 1 h after injection of the radiolabeled mAb. Peripheral B cells were coated with CD19, resulting in partial modulation of CD19, most pronounced in the three pretreated patients. Whole-body images were obtained with a gamma camera and compared with results obtained by conventional imaging techniques. Initially, blood-pool activity dominated, whereas 24 h after injection the radioactivity was mainly located in the spleen, kidneys and liver. In two patients, a lesion in the spleen appeared as an unlabeled spot. In one patient, a lesion in the femur, which was detected by computed tomography (CT) and gallium-67 scans, was also seen on the CD19 scan from 1 h after administration of the radioimmunoconjugate onwards. Good imaging of bone marrow infiltration was observed in one of three patients. Lymph node involvement was not observed in any of the patients in whom affected lymph nodes were detected by CT or gallium-67 scan. In conclusion, in the present study radioimmunodetection with ^99mTc-labeled CD19 mAb was found to be inferior to CT and gallium-67 scanning in the diagnosis of patients with B cell non-Hodgkin’s lymphoma. Received: 14 March 1996 / Accepted: 14 May 1996     

Single-Molecule Microscopy Reveals Membrane Microdomain Organization of Cells in a Living Vertebrate

It has been possible for several years to study the dynamics of fluorescently labeled proteins by single-molecule microscopy, but until now this technology has been applied only to individual cells in culture. In this study, it was extended to stem cells and living vertebrate organisms. As a molecule of interest we used yellow fluorescent protein fused to the human H-Ras membrane anchor, which has been shown to serve as a model for proteins anchored in the plasma membrane. We used a wide-field fluorescence microscopy setup to visualize individual molecules in a zebrafish cell line (ZF4) and in primary embryonic stem cells. A total-internal-reflection microscopy setup was used for imaging in living organisms, in particular in epidermal cells in the skin of 2-day-old zebrafish embryos. Our results demonstrate the occurrence of membrane microdomains in which the diffusion of membrane proteins in a living organism is confined. This membrane organization differed significantly from that observed in cultured cells, illustrating the relevance of performing single-molecule microscopy in living organisms.     

Effect of a single 3''-methylene phosphonate linkage on the conformation of an A-DNA octamer double helix.

The three-dimensional structure of the self-complementary DNA octamer d(GCCCGpGGC) has been determined in the crystalline state using X-ray diffraction data to a nominal resolutoin of 2.12 measured from a very small crystal at DESY, Hamburg. The structure was refined with stereochemical restraints to an R value of 17.1%. d(GCCCGpGGC), containing one single 3'-methylene phosphonate linkage (denoted p), forms an A-DNA double helix with strict dyad symmetry, that is distinct from canonical A-DNA by a wide open major groove and a small average base-pair inclination against the helix axis. The conformation of the unmodified control d(GCCCGGGC) is known from an X-ray analysis of isomorphous crystals (Heinemann et al. (1987) Nucleic Acids Res. 15, 9531-9550). Comparison of the two structures reveals only minor conformational differences, most notably in the pucker of the reduced deoxyribose. It is suggested that oligonucleotides with charged 3'-methylene phosphonate groups may form stable duplexes with complementary DNA or RNA strands rendering them candidates for use as gene-regulatory antisense probes.     

Enterococcal surface protein Esp is important for biofilm formation of Enterococcus faecium E1162

Enterococci have emerged as important nosocomial pathogens with resistance to multiple antibiotics. Adhesion to abiotic materials and biofilm formation on medical devices are considered important virulence properties. A single clonal lineage of Enterococcus faecium, complex 17 (CC17), appears to be a successful nosocomial pathogen, and most CC17 isolates harbor the enterococcal surface protein gene, esp. In this study, we constructed an esp insertion-deletion mutant in a clinical E. faecium CC17 isolate. In addition, initial adherence and biofilm assays were performed. Compared to the wild-type strain, the esp insertion-deletion mutant no longer produced Esp on the cell surface and had significantly lower initial adherence to polystyrene and significantly less biofilm formation, resulting in levels of biofilm comparable to those of an esp-negative isolate. Capacities for initial adherence and biofilm formation were restored in the insertion-deletion mutant by in trans complementation with esp. These results identify Esp as the first documented determinant in E. faecium CC17 with an important role in biofilm formation, which is an essential factor in infection pathogenesis.     

Contribution of the enterococcal surface protein Esp to pathogenesis of Enterococcus faecium endocarditis

The enterococcal surface protein Esp, specifically linked to nosocomial Enterococcus faecium, is involved in biofilm formation. To assess the role of Esp in endocarditis, a biofilm-associated infection, an Esp-expressing E. faecium strain (E1162) or its Esp-deficient mutant (E1162Δesp) were inoculated through a catheter into the left ventricle of rats. After 24 h, less E1162Δesp than E1162 were recovered from heart valve vegetations. In addition, anti-Esp antibodies were detected in Esp-positive E. faecium bacteremia and endocarditis patient sera. In conclusion, Esp contributes to colonization of E. faecium at the heart valves. Furthermore, systemic infection elicits an Esp-specific antibody response in humans.