Outer membrane vesicles of Tannerella forsythia: biogenesis, composition, and virulence.

Tannerella forsythia is the only 'red-complex' bacterium covered by an S-layer, which has been shown to affect virulence. Here, outer membrane vesicles (OMVs) enriched with putative glycoproteins are described as a new addition to the virulence repertoire of T. forsythia. Investigations of this bacterium are hampered by its fastidious growth requirements and the recently discovered mismatch of the available genome sequence (92A2 = ATCC BAA-2717) and the widely used T. forsythia strain (ATCC 43037). T. forsythia was grown anaerobically in serum-free medium and biogenesis of OMVs was analyzed by electron and atomic force microscopy. This revealed OMVs with a mean diameter of ~100 nm budding off from the outer membrane while retaining the S-layer. An LC-ESI-TOF/TOF proteomic analysis of OMVs from three independent biological replicates identified 175 proteins. Of these, 14 exhibited a C-terminal outer membrane translocation signal that directs them to the cell/vesicle surface, 61 and 53 were localized to the outer membrane and periplasm, respectively, 22 were predicted to be extracellular, and 39 to originate from the cytoplasm. Eighty proteins contained the Bacteroidales O-glycosylation motif, 18 of which were confirmed as glycoproteins. Release of pro-inflammatory mediators from the human monocytic cell line U937 and periodontal ligament fibroblasts upon stimulation with OMVs followed a concentration-dependent increase that was more pronounced in the presence of soluble CD14 in conditioned media. The inflammatory response was significantly higher than that caused by whole T. forsythia cells. Our study represents the first characterization of T. forsythia OMVs, their proteomic composition and immunogenic potential.

Potential of the Tannerella forsythia S-layer to delay the immune response.

UNLABELLED: The periodontal pathogen Tannerella forsythia possesses a glycosylated S-layer as an outermost cell decoration. While the S-layer provides a selection advantage to the bacterium in the natural habitat, its virulence potential remains to be investigated. In the present study, the immune responses of human macrophages and gingival fibroblasts upon stimulation with wild-type T. forsythia and an S-layer-deficient mutant were investigated. The mRNA expression levels of the pro-inflammatory mediators IL-1ß, TNF-α, and IL-8 were analyzed by qPCR, and the production of the corresponding cytokines was investigated by ELISA. The S-layer-deficient T. forsythia mutant induced significantly higher levels of pro-inflammatory mediators compared with wild-type T. forsythia, especially at the early phase of response. Analysis of these data suggests that the S-layer of T. forsythia is an important virulence factor that attenuates the host immune response to this pathogen by evading the bacterium's recognition by the innate immune system. ABBREVIATIONS: DMSO, dimethylsulfoxide; FBS, fetal bovine serum; GAPDH, glycerinaldehyde-3-phosphate-dehydrogenase; HGFs, human gingival fibroblasts; LPS, lipopolysaccharide; MEM, minimal essential medium; MTT, 3,4,5-dimethylthiazol-2-yl-2,5-diphenyl tetrazolium bromide; OD, optical density; PBS, phosphate-buffered saline; qPCR, quantitative polymerase chain-reaction; SD, standard deviation; Tannerella forsythia ATCC 43037, Tf wt; Tannerella forsythia ATCC 43037 S-layer mutant, Tf ΔtfsAB.

[Characteristics of the heart rate of emergency physicians in emergency helicopters]. / Herzfrequenzverhalten von Notärzten beim Einsatz im Notarzthubschrauber.

The heart rate behaviour of 14 emergency doctors was examined in 50 cases of medical emergency service by helicopter. In addition, the subjective stress experienced by the probands was inquired by means of a questionnaire. The alarm and the landing at the site of the emergency resulted in the most marked heart rate increases; also during the period of approaching the patient, his rescue and care, persistent tachycardia could be observed. Recovery began slowly during the return flight, but even 15 minutes after completion of the emergency task the heart rate was still higher than the original value before the alarm had been sounded. Subjectively the total stress was considered to be generally low in the opinion of the emergency doctors. It seems that unconscious mechanisms of repression prevent the actual realistic recording of physical and emotional stress during the emergency service by helicopter.

[Lesion of the brachial plexus, caused by wrong positioning during surgery]. / Läsion des Plexus brachialis, verursacht durch fehlerhafte Operationslagerungen.

We report three patients, which showed plexus palsies after routine operations. Compression and stretch of the nerves despite pads leaded to nerve injury in patient A. Abduction of the arm, fixed wrist, hypotension in steep Trendelenburg position and a preexisting shoulder-arm-syndrome were the causes in patient B. Hyperreclination of the head in semisitting position caused the lesion in patient C. The anaesthetist should know the risks of positioning to prevent nerve injuries.