[Dizziness and vertigo in a tertiary ENT emergency department]. / Schwindelerkrankungen in einem tertiären HNO-Notfallzentrum.

BACKGROUND: Although vestibular symptoms are amongst the most frequent reasons for seeking emergency medical help, many patients remain undiagnosed. OBJECTIVE: In this cross-sectional study, we investigated the spectrum of vertigo and dizziness in a tertiary ear, nose, and throat (ENT) emergency department (ED). Furthermore, we investigated the attendant symptoms, clinical signs, and the diagnostic tests performed. METHODS: We screened all ED reports from 01/2013 to 12/2013 for adult patients with vestibular symptoms referred to the ENT department. RESULTS: In total, we found 2596 cases with reported vestibular symptoms in the ED as a main or accompanying complaint. Of these, 286 were referred to the ENT specialist directly (n = 98) or via other major medical specialties (n = 188). Benign paroxysmal positional vertigo (BPPV) was the most frequent diagnosis in our study (n = 46, 16.1%), followed by vestibular neuritis (n = 44, 15.4%), otitis media (n = 20, 7%), and 9 patients (3.1%) had an ischemic stroke or a transient ischemic attack. In 70 (24.5%) cases, dizziness was not further specified. CONCLUSION: BPPV is the most frequent diagnosis seen in the ED; however, physicians need to document nystagmus more precisely and perform diagnostic tests systematically, in order to make an accurate diagnosis. To avoid misdiagnoses, ED physicians and ENT specialists should be able to recognize central signs in patients with an acute vestibular syndrome. Every fourth patient does not receive a definitive diagnosis. Diagnostic ED workup for patients with dizziness needs further improvement.

Characterization of intact subcellular bodies in whole bacteria by cryo-electron tomography and spectroscopic imaging.

We illustrate the combined use of cryo-electron tomography and spectroscopic difference imaging in the study of subcellular structure and subcellular bodies in whole bacteria. We limited our goal and focus to bodies with a distinct elemental composition that was in a sufficiently high concentration to provide the necessary signal-to-noise level at the relatively large sample thicknesses of the intact cell. This combination proved very powerful, as demonstrated by the identification of a phosphorus-rich body in Caulobacter crescentus. We also confirmed the presence of a body rich in carbon, demonstrated that these two types of bodies are readily recognized and distinguished from each other, and provided, for the first time to our knowledge, structural information about them in their intact state. In addition, we also showed the presence of a similar type of phosphorus-rich body in Deinococcus grandis, a member of a completely unrelated bacteria genus. Cryo-electron microscopy and tomography allowed the study of the biogenesis and morphology of these bodies at resolutions better than 10 nm, whereas spectroscopic difference imaging provided a direct identification of their chemical composition.

Mapping of a protein-RNA kissing hairpin interface: Rom and Tar-Tar*.

An RNA 'kissing' complex is formed by the association of two hairpins via base pairing of their complementary loops. This sense-antisense RNA motif is used in the regulation of many cellular processes, including Escherichia coli ColE1 plasmid copy number. The RNA one modulator protein (Rom) acts as a co-regulator of ColE1 plasmid copy number by binding to the kissing hairpins and stabilizing their interaction. We have used heteronuclear two-dimensional NMR spectroscopy to map the interface between Rom and a kissing complex formed by the loop of the trans -activation response (Tar) element of immunodeficiency virus 1 (HIV-1) and its complement. The protein binding interface was obtained from changes in amide proton signals of uniformly 15N-labeled Rom with increasing concentrations of unlabeled Tar-Tar*. Similarly, the RNA-binding interface was obtained from changes in imino proton signals of uniformly 15N-labeled Tar with increasing concentrations of unlabeled Rom. Our results are in agreement with previous mutagenesis studies and provide additional information on Rom residues involved in RNA binding. The kissing hairpin interface with Rom leads to a model in which the protein contacts the minor groove of the loop-loop helix and, to a lesser extent, the major groove of the stems.

Structural studies of the Escherichia coli signal transducing protein IIAGlc: implications for target recognition.

In Escherichia coli, the glucose-specific phosphocarrier protein of the phosphotransferase system (PTS), IIAGlc (IIIGlc in older literature), is also the central regulatory protein of the PTS. Depending upon its state of phosphorylation, IIAGlc binds to a number of different proteins that display no apparent sequence homology. Previous structural studies suggested that nonspecific hydrophobic interactions, specific salt bridges, and an intermolecular Zn(II) binding site contribute to the wide latitude in IIAGlc binding sites. Two new crystal forms of IIAGlc have been solved at high resolution, and the models were compared to those previously studied. The major intermolecular contacts in the crystals differ in detail, but all involve the hydrophobic active site of IIAGlc interacting with a hydrophobic patch on a neighbor and all are shown to be surprisingly similar to the physiologically relevant regulatory interaction of IIAGlc with glycerol kinase. In two crystal forms, a helix on one molecule interacts with the face of another, while in the other crystal form, the primary crystal contact consists of a strand of beta-sheet that contributes to an intermolecular Zn(II) binding site with tetrahedral ligation identical to that of the zinc peptidase thermolysin. Thus, relatively nonspecific hydrophobic interactions combined with specific salt bridges and an intermolecular cation binding site (cation-promoted association) permit a regulatory protein to bind to target proteins that have little or no sequence or structural homology with one another. It is suggested that signal transduction by IIAGlc is a binary switch in which phosphorylation at the active site directly controls binding to target molecules.