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[en] Determining the structural origins of amyloid fibrillation is essential for understanding both the pathology of amyloidosis and the rational design of inhibitors to prevent or reverse amyloid formation. In this work, the decisive roles of peptide structures on amyloid self-assembly and morphological diversity were investigated by the design of eight amyloidogenic peptides derived from islet amyloid polypeptide. Among the segments, two distinct morphologies were highlighted in the form of twisted and planar (untwisted) ribbons with varied diameters, thicknesses, and lengths. In particular, transformation of amyloid fibrils from twisted ribbons into untwisted structures was triggered by substitution of the C-terminal serine with threonine, where the side chain methyl group was responsible for the distinct morphological change. This effect was confirmed following serine substitution with alanine and valine and was ascribed to the restriction of intersheet torsional strain through the increased hydrophobic interactions and hydrogen bonding. We also studied the variation of fibril morphology (i.e., association and helicity) and peptide aggregation propensity by increasing the hydrophobicity of the peptide side group, capping the N-terminus, and extending sequence length. Lastly, we anticipate that our insights into sequence-dependent fibrillation and morphological diversity will shed light on the structural interpretation of amyloidogenesis and development of structure-specific imaging agents and aggregation inhibitors.
[en] The purpose of this study was to describe a new technique called MR plastination arthrography to study both intra- and extra-articular anatomy. In six human cadaveric lower legs MR arthrography was performed in either a one-step or two-step procedure. In the former a mixture of diluted Gadolinium and dyed polymer was injected. In the latter the dyed polymer was injected after arthrography wih diluted Gadolinium. Three-millimeter slices of these legs, obtained in a plane identical to that of the MR images, were plastinated according to the E12 technique of von Hagens. The plastination slices were subsequently compared with the MR images. The one-step procedure resulted in an inhomogeneous arthrogram. The two-step procedure resulted in a good correlation between the high-resolution MR images and plastination slices, as expressed by a good comparison of anatomic detail of the small syndesmotic recess. Images of the distal tibiofibular syndesmosis obtained with plastination arthrography correlated well with images acquired by MR arthrography when performed in a two-step procedure. (orig.)
[en] The size distribution and body condition of the two morphotypes of green turtle (Chelonia mydas) foraging in Gorgona Natural National Park (GNNP) in the Colombian Pacific was assessed from 2003 to 2012. Measurements of straight carapace length (SCL), curved carapace length (CCL), weight, and body condition of 1,023 turtles captured on the GNNP reefs were recorded. More black turtles (n = 747) than yellow turtles (n = 276) were captured, all of them juveniles. Black turtles were significantly larger and heavier than yellow turtles. The size of recruitment to the neritic zone was 40.0-49.9 cm SCL for both morphotypes, but there were more yellow than black turtles in this size class, indicating a difference in the recruitment pattern. The body condition index of yellow turtles was significantly higher than that of black turtles, which could indicate differences in resource use. Based on our results, we suggest that GNNP might function as a recruitment area for yellow turtles, which arrive at smaller sizes and as part of a coastal migratory route for black turtles, which arrive at larger sizes and maintain residence at this location for an unknown period of time.
[en] Currently ocular biometric measurements are defined by US and are measured from the orbital walls. These bony landmarks cannot be seen by MRI, and therefore these measurements cannot be directly applied. To define measurements of normal growth of the fetal eyes using MRI. Transorbital views were analyzed in 198 fetal MR examinations. The ocular diameter (OD) and interocular and binocular distances (IOD and BOD) were measured and were plotted against gestational age. Fetuses with abnormalities affecting the eyes were evaluated separately. Of 198 scans, 146 had suitable images, 35 of which were abnormal. Normal growth of BOD, IOD and OD were determined, and compared with the respective already established US data. Normal growth charts were derived from a cohort of 111 normal fetuses. Because the margins of the vitreous are inside the bony orbit, at the same gestational age measurements of the BOD and OD are always less than the corresponding measurements by US, and those of the IOD are always more. Normal growth charts for MRI can now be used to support suspected diagnoses of orbital and ocular pathologies and the syndromes that give rise to them, and many examples are demonstrated. (orig.)
[en] Multi-scale and fractal morphologies are ubiquitous in experiments. Accurate statements about sizes of domains and interfaces, roughness exponents, fractal dimensions, etc. can be obtained from the correlation function 𝐶(𝑟) and the structure factor 𝑆(𝑘). Smooth morphologies are characterized by the Porod law. The signature of fractal domains and interfaces is a power-law decay of 𝐶(𝑟) and 𝑆(𝑘) with non-integer exponents. As typical experimental morphologies are smooth on some length scales and fractal on others, the structure factor is characterized by cross-overs from one form to another. We illustrate this with two examples: (i) ground state morphologies in dilute anti-ferromagnets; and (ii) droplet-in-droplet morphologies of double-phase-separating mixtures. The identification of fractal morphologies in these systems yields novel insights on the underlying micro-scale phenomena. (author)
[en] The aim of this study was to evaluate the characteristics and CT features of subcarinal air collections on thin-section multidetector-row computed tomography (MDCT). Two hundred asymptomatic adult subjects without a history of pulmonary disease underwent MDCT. The CT appearances and characteristics of foci of extraluminal air contiguous to the main bronchus in the subcarinal region were retrospectively analysed. Subcarinal air collections were found in 81 of 200 subjects (41%) and were spotty or microtubular in 67 of 81 subjects and rounded or oval in the other 14. Each subcarinal air focus communicated, or seemed to communicate, with the adjacent bronchus in 76 of 81 cases. Our data demonstrate that extraluminal air foci in the subcarinal region are common CT findings and routinely depicted on thin-section MDCT, and that most of these lesions seem to be main bronchial diverticula. Cystic air foci in the subcarinal region should be called subcarinal air cysts. The precise recognition of these cysts improves the ability to avoid misidentification, such as pneumomediastinum. (orig.)
[en] Highlights: • Morphological changes of the gold Nanorods-decorated electrospun nanofibers were controlled by applying thermal treatment. • The decorated nanorods became short, and finally round with the increasing thermal treating time. • The SERS activity of the changing nanostructure firstly increased and then decreased with the thermal treating time. • The catalytic property of the changing nanostructure monotonously decreased with the thermal treating time. Understanding the structure-property relationships of functional materials with changing nanostructures is essential for their practical applications. In this work, the nanorods-decorated electrospun nanofibers underwent a morphology evolution upon simple thermal treatment. The nanorods became short, and finally round with the increasing thermal treating time. As results of the morphology evolution, the SERS properties and the catalytic properties of the changing nanostructures showed different trends. The SERS activity firstly increased and then decreased with the thermal treating time. However, the catalytic property decreased with the thermal treating time. The revealed connections between the practical performance and the morphology evolution might be helpful for the control of functionality of nanomaterials under certain conditions.
[en] To evaluate effects of a vascular-disrupting agent on rodent tumour models. Twenty rats with liver rhabdomyosarcomas received ZD6126 intravenously at 20 mg/kg, and 10 vehicle-treated rats were used as controls. Multiple sequences, including diffusion-weighted imaging (DWI) and dynamic contrast-enhanced MRI (DCE-MRI) with the microvascular permeability constant (K), were acquired at baseline, 1 h, 24 h and 48 h post-treatment by using 1.5-T MRI. [18F]fluorodeoxyglucose micro-positron emission tomography (18F-FDG μPET) was acquired pre- and post-treatment. The imaging biomarkers including tumour volume, enhancement ratio, necrosis ratio, apparent diffusion coefficient (ADC) and K from MRI, and maximal standardised uptake value (SUVmax) from FDG μPET were quantified and correlated with postmortem microangiography and histopathology. In the ZD6126-treated group, tumours grew slower with higher necrosis ratio at 48 h (P < 0.05), corresponding well to histopathology; tumour K decreased from 1 h until 24 h, and partially recovered at 48 h (P < 0.05), parallel to the evolving enhancement ratios (P < 0.05); ADCs varied with tumour viability and perfusion; and SUVmax dropped at 24 h (P < 0.01). Relative K of tumour versus liver at 48 h correlated with relative vascular density on microangiography (r = 0.93, P < 0.05). The imaging biomarkers allowed morphological, functional and metabolic quantifications of vascular shutdown, necrosis formation and tumour relapse shortly after treatment. A single dose of ZD6126 significantly diminished tumour blood supply and growth until 48 h post-treatment. (orig.)