Aggregative Adherence and Intestinal Colonization by Enteroaggregative Escherichia coli Are Produced by Interactions among Multiple Surface Factors.

Enteroaggregative Escherichia coli (EAEC) bacteria are exceptional colonizers that are associated with diarrhea. The genome of EAEC strain 042, a diarrheal pathogen validated in a human challenge study, encodes multiple colonization factors. Notable among them are aggregative adherence fimbriae (AAF/II) and a secreted antiaggregation protein (Aap). Deletion of aap is known to increase adherence, autoaggregation, and biofilm formation, so it was proposed that Aap counteracts AAF/II-mediated interactions. We hypothesized that Aap sterically masks heat-resistant agglutinin 1 (Hra1), an integral outer membrane protein recently identified as an accessory colonization factor. We propose that this masking accounts for reduced in vivo colonization upon hra1 deletion and yet no colonization-associated phenotypes when hra1 is deleted in vitro. Using single and double mutants of hra1, aap, and the AAF/II structural protein gene aafA, we demonstrated that increased adherence in aap mutants occurs even when AAF/II proteins are genetically or chemically removed. Deletion of hra1 together with aap abolishes the hyperadherence phenotype, demonstrating that Aap indeed masks Hra1. The presence of all three colonization factors, however, is necessary for optimal colonization and for rapidly building stacked-brick patterns on slides and cultured monolayers, the signature EAEC phenotype. Altogether, our data demonstrate that Aap serves to mask nonstructural adhesins such as Hra1 and that optimal colonization by EAEC is mediated through interactions among multiple surface factors. IMPORTANCE Enteroaggregative Escherichia coli (EAEC) bacteria are exceptional colonizers of the human intestine and can cause diarrhea. Compared to other E. coli pathogens, little is known about the genes and pathogenic mechanisms that differentiate EAEC from harmless commensal E. coli. EAEC bacteria attach via multiple proteins and structures, including long appendages produced by assembling molecules of AafA and a short surface protein called Hra1. EAEC also secretes an antiadherence protein (Aap; also known as dispersin) which remains loosely attached to the cell surface. This report shows that dispersin covers Hra1 such that the adhesive properties of EAEC seen in the laboratory are largely produced by AafA structures. When the bacteria colonize worms, dispersin is sloughed off, or otherwise removed, such that Hra1-mediated adherence occurs. All three factors are required for optimal colonization, as well as to produce the signature EAEC stacked-brick adherence pattern. Interplay among multiple colonization factors may be an essential feature of exceptional colonizers.

Impact of osteopathic therapy on proprioceptive balance and quality of life in patients with dizziness.

The aim of the study was to evaluate the efficacy of osteopathic manipulative treatment (OMT) in patients with Benign-Paroxysmal-Positional Vertigo (BPPV). Thirty-one patients with BPPV were randomly assigned into two groups: 19 patients received osteopathic treatments (TG) and 12 patients received sham therapy (SG), both in four weekly sessions. Before the first and the last treatment, those patients were evaluated using Dizziness Handicap Inventory (DHI) and stabilometric platform to assess lifestyle modification and balance functions. After the treatment session, TG compared to SG showed an improvement in DHI global (p = 0.02), functional (p = 0.03) and physical (p = 0.03) components, as well as a reduction of swinging area (p = 0.02). An association between swinging area and lifestyle measures (global [r = 0.53; p = 0.02]; functional [r = 0.50; p = 0.03]; physical [r = 0.60; p = 0.01]) changes were found in TG. These findings suggest that OMT could be a useful approach to reduce imbalance symptoms and to improve the quality of life in patients suffering from dizziness.

Slow-wave oscillations in the craniosacral space: a hemoliquorodynamic concept of origination.

The mechanism of formation of rhythmic, slow-wave oscillations in the craniospinal cavity were studied. Synchronous bioimpedance traces were made of the head and lumbosacral part of the spine in five healthy young subjects at rest and during voluntary breath-holding; these reflect changes in the ratios of blood and CSF volumes in these parts of the craniospinal space. Computer amplitude-frequency and spectral analysis of the data (Macintosh G-4, Chart-5.2) demonstrated slow (6-12 cycles/min) and rapid (pulsatile) oscillations in different directions in the cranial and lumbosacral areas. These data suggested a hemoliquorodynamic hypothesis for the craniosacral rhythm. The pulsatile and slow-wave oscillations of cerebrovascular tone and intracranial pressure evidently initiate to-and-fro displacements of the CSF in the caudal direction. The associated tonic contractions of the musculature of the lumbar part of the spine and the mobility of the sacrum are detected manually as the craniosacral rhythm.

[Slow-wave fluctuations in craniosacral space: hemo-liquorodynamic conception of origin].

In the paper, the mechanism of forming of rhythmic slow-wave fluctuations in craniospinal cavity was investigated. In five young healthy persons, at rest and under voluntary respiration arrest test, the bioimpedansograms of head and lumbosacral part of vertebral column were synchronously registered as these recordings reflect the changes of relationships between blood/CSF volumes in cranial and lumbosacral regions, respectively. The recordings were subjected to frequency and spectral computer analysis (PC Macintosh G-4, Chart 5.2. software). The rapid (pulsatile) as well as slow and counter-directed waves (frequency 6-10 cycles/min) of these processes were revealed in cranial and lumbosacral regions. The data obtained suggest the CSF dynamic concept of origin of the craniosacral rhythm. The pulse and slow-frequency oscillations of the cerebral vessels tone initiate corresponding intracranial pressure waves, and the latter are the motivating forces for to-and-fro CSF shifts in caudal direction. This mechanism is accompanied by tonic contractions of lumbar muscles and sacrum movements, and it is manually perceptible as a craniosacral rhythm.