Spontaneous Spondylodiscitis - Epidemiology, Clinical Features, Diagnosis and Treatment.

Spontaneous spondylodiscitis is a rare but serious infectious disease which is a combination of an inflammatory process, involving one or more adjacent vertebral bodies (spondylitis), the intervertebral discs (discitis) and finally - the neighboring neural structures. In most cases the condition is due to a hematogenous infection and can affect all regions of the spinal cord, but it is usually localized in the lumbar area. The most common clinical symptom is a pronounced, constant and increasing nocturnal paravertebral pain, while consequently different degrees of residual neurological symptoms from nerve roots and/or spinal cord may appear.

An Achilles' heel in an amyloidogenic protein and its repair: insulin fibrillation and therapeutic design.

Insulin fibrillation provides a model for a broad class of amyloidogenic diseases. Conformational distortion of the native monomer leads to aggregation-coupled misfolding. Whereas beta-cells are protected from proteotoxicity by hexamer assembly, fibrillation limits the storage and use of insulin at elevated temperatures.

Polymorphic fibril formation by residues 10-40 of the Alzheimer's beta-amyloid peptide.

We report investigations of the morphology and molecular structure of amyloid fibrils comprised of residues 10-40 of the Alzheimer's beta-amyloid peptide (Abeta(10-40)), prepared under various solution conditions and degrees of agitation. Omission of residues 1-9 from the full-length Alzheimer's beta-amyloid peptide (Abeta(1-40)) did not prevent the peptide from forming amyloid fibrils or eliminate fibril polymorphism. These results are consistent with residues 1-9 being disordered in Abeta(1-40) fibrils, and show that fibril polymorphism is not a consequence of disorder in residues 1-9.

Experimental constraints on quaternary structure in Alzheimer's beta-amyloid fibrils.

We describe solid-state nuclear magnetic resonance (NMR) measurements on fibrils formed by the 40-residue beta-amyloid peptide associated with Alzheimer's disease (Abeta(1-40)) that place constraints on the identity and symmetry of contacts between in-register, parallel beta-sheets in the fibrils. We refer to these contacts as internal and external quaternary contacts, depending on whether they are within a single molecular layer or between molecular layers. The data include (1) two-dimensional 13C-13C NMR spectra that indicate internal quaternary contacts between side chains of L17 and F19 and side chains of I32, L34, and V36, as well as external quaternary contacts between side chains of I31 and G37; (2) two-dimensional 15N-13C NMR spectra that indicate external quaternary contacts between the side chain of M35 and the peptide backbone at G33; (3) measurements of magnetic dipole-dipole couplings between the side chain carboxylate group of D23 and the side chain amine group of K28 that indicate salt bridge interactions.

Abeta40-Lactam(D23/K28) models a conformation highly favorable for nucleation of amyloid.

Recent solid-state NMR data (1) demonstrate that Abeta(1)(-)(40) adopts a conformation in amyloid fibrils with two in-register, parallel beta-sheets, connected by a bend structure encompassing residues D(23)VGSNKG(29), with a close contact between the side chains of Asp23 and Lys28. We hypothesized that forming this bend structure might be rate-limiting in fibril formation, as indicated by the lag period typically observed in the kinetics of Abeta(1)(-)(40) fibrillogenesis. We synthesized Abeta(1)(-)(40)-Lactam(D23/K28), a congener Abeta(1)(-)(40) peptide that contains a lactam bridge between the side chains of Asp23 and Lys28.

Self-propagating, molecular-level polymorphism in Alzheimer's beta-amyloid fibrils.

Amyloid fibrils commonly exhibit multiple distinct morphologies in electron microscope and atomic force microscope images, often within a single image field. By using electron microscopy and solid-state nuclear magnetic resonance measurements on fibrils formed by the 40-residue beta-amyloid peptide of Alzheimer's disease (Abeta(1-40)), we show that different fibril morphologies have different underlying molecular structures, that the predominant structure can be controlled by subtle variations in fibril growth conditions, and that both morphology and molecular structure are self-propagating when fibrils grow from preformed seeds. Different Abeta(1-40) fibril morphologies also have significantly different toxicities in neuronal cell cultures.

Rotational resonance in uniformly 13C-labeled solids: effects on high-resolution magic-angle spinning NMR spectra and applications in structural studies of biomolecular systems.

We describe investigations of the effects of rotational resonance (R(2)) on solid state (13)C NMR spectra of uniformly (13)C-labeled samples obtained under magic-angle spinning (MAS), and of the utility of R(2) measurements as structural probes of peptides and proteins with multiple uniformly labeled residues. We report results for uniformly (13)C-labeled L-alanine and L-valine in polycrystalline form, and for amyloid fibrils formed by the 15-residue peptide A beta(11-25) with uniform labeling of a four-residue segment. The MAS NMR spectra reveal a novel J-decoupling effect at R(2) conditions that may be useful in spectral assignments for systems with sharp (13)C MAS NMR lines.

Backbone and side chain assignment strategies for multiply labeled membrane peptides and proteins in the solid state.

We demonstrate that the SPECIFIC CP technique can be used to obtain heteronuclear correlation (HETCOR) spectra of peptide backbones with greater efficiency than conventional HETCOR methods. We show that similar design principles can be employed to achieve selective homonuclear polarization transfer mediated through dipolar or scalar couplings. Both approaches are demonstrated in a tripeptide with uniform 15N and 13C labeling, and with uniform 15N labeling and natural abundance 13C.

A structural model for Alzheimer's beta -amyloid fibrils based on experimental constraints from solid state NMR.

We present a structural model for amyloid fibrils formed by the 40-residue beta-amyloid peptide associated with Alzheimer's disease (Abeta(1-40)), based on a set of experimental constraints from solid state NMR spectroscopy. The model additionally incorporates the cross-beta structural motif established by x-ray fiber diffraction and satisfies constraints on Abeta(1-40) fibril dimensions and mass-per-length determined from electron microscopy. Approximately the first 10 residues of Abeta(1-40) are structurally disordered in the fibrils.

Supramolecular structure in full-length Alzheimer's beta-amyloid fibrils: evidence for a parallel beta-sheet organization from solid-state nuclear magnetic resonance.

We report constraints on the supramolecular structure of amyloid fibrils formed by the 40-residue beta-amyloid peptide associated with Alzheimer's disease (A beta(1-40)) obtained from solid-state nuclear magnetic resonance (NMR) measurements of intermolecular dipole-dipole couplings between (13)C labels at 11 carbon sites in residues 2 through 39. The measurements are carried out under magic-angle spinning conditions, using the constant-time finite-pulse radiofrequency-driven recoupling (fpRFDR-CT) technique. We also present one-dimensional (13)C magic-angle spinning NMR spectra of the labeled A beta(1-40) samples.

Sensitivity enhancement in structural measurements by solid state NMR through pulsed spin locking.

Free induction decay (FID) signals in solid state NMR measurements performed with magic angle spinning can often be extended in time by factors on the order of 10 by a simple pulsed spin locking technique. The sensitivity of a structural measurement in which the structural information is contained in the dependence of the integrated FID amplitude on a preceding evolution period can therefore be enhanced substantially by pulsed spin locking in the signal detection period. We demonstrate sensitivity enhancements in a variety of solid state NMR techniques that are applicable to selectively isotopically labeled samples, including 13C-15N rotational echo double resonance (REDOR), 13C-13C dipolar recoupling measurements using the constant-time finite-pulse radio-frequency-driven recoupling (fpRFDR-CT) and constant-time double-quantum-filtered dipolar recoupling (CTDQFD) techniques, and torsion angle measurements using the double quantum chemical shift anisotropy (DQCSA) technique.

Tryptophan interactions in bacteriorhodopsin: a heteronuclear solid-state NMR study.

The bulky and amphiphilic nature of tryptophan residues makes them particularly interesting components of proteins. In bacteriorhodopsin, four of the eight tryptophan residues are in the active site, forming parts of the retinal binding pocket. In this work, we use solid-state NMR to study the interactions of the tryptophan residues in wild-type bacteriorhodopsin, in the resting state, and in critical intermediates of the proton-motive photocycle.