Low packing densities are key structural features of amphidynamic crystals built with static and mobile components. Here we report a loosely packed crystal of dendrimeric rotor, 2, and the fast dynamics of all its aromatic groups, both resulting from the hyperbranched structure of the molecule. Compound 2 was synthesized with a convergent strategy to construct a central phenylene core with stators consisting of two layers of triarylmethyl groups. Single crystal X-ray diffraction analysis confirmed a low-density packing structure consisting of one molecule of 2 and approximately eight solvent molecules per unit cell. Three isotopologues of 2 were synthesized to study the motion of each segment in the molecule in the solid state using variable temperature quadrupolar echo 2H NMR spectroscopy. Line shape analysis of the spectra reveals that the central phenylene, the six branch phenylenes and the eighteen periphery phenyls all display megahertz rotational dynamics in the crystals at ambient temperature. Arrhenius analysis of the data gives similar activation energies and pre-exponential factors for different parts of the structure. The observed pre-exponential factors are 4–6 orders of magnitude greater than those of elementary site-exchange processes, indicating that the dynamics are not dictated by static energetic potentials. Instead, the activation energies for rotations in the crystals of 2 are controlled by temperature dependent local structural fluctuations and crystal fluidity.

BACKGROUND AND PURPOSE:Atypical clinical presentations of spontaneous intracranial hypotension include obtundation, memory deficits, dementia with frontotemporal features, parkinsonism, and ataxia . The purpose of this study was to compare clinical and imaging features of spontaneous intracranial hypotension with typical-versus-atypical presentations.

Purpose To assess the feasibility of ferumoxytol-enhanced anesthesia-free cardiac MRI in neonates and young infants for complex congenital heart disease (CHD). Methods With IRB-approval, 21 consecutive neonates and young infants (1 day – 11 weeks old, median age of 3 days) who underwent a rapid two-sequence (MRA and 4D flow) MRI protocol with intravenous ferumoxytol without sedation (n = 17) or light sedation (n = 4) at 3T (except one case at 1.5T) between June 2014 and February 2016 were retrospectively identified. Medical records were reviewed for indication, any complications, if further diagnostic imaging was performed after MRI, and surgical findings. Two radiologists scored the images in two sessions on a five-point scale for overall image quality and delineation of various anatomical structures. Confidence interval of proportions for likelihood of requiring additional diagnostic imaging after MRI was determined. For the possibility of reducing the protocol to a single rapid sequence, Wilcoxon-rank sum test was used to assess whether 4D flow and MRA significantly differed in anatomical delineation. Results One of 21 patients (4.8%, 80% confidence interval 0–11%) required additional imaging, a CTA to assess lung parenchyma and peripheral pulmonary arteries. Only 1 out of 13 patients (7.7%) with operative confirmation had a minor discrepancy between radiology and operative reports (80% confidence interval 0–17%). 4D flow was significantly superior to MRA (p<0.05) for the evaluation of systemic arteries, valves, ventricular trabeculae, and overall quality. Using Cohen’s kappa coefficient, there was good interobserver agreement for the evaluation of systemic arteries by 4D flow (κ = 0.782), and systemic veins and pulmonary arteries by MRA (κ > 0.6). Overall 4D flow measurements (mean κ = 0.64–0.74) had better internal agreement compared to MRA (mean κ = 0.30–0.64). Conclusion Ferumoxytol-enhanced cardiac MRI, without anesthesia, is feasible for the evaluation of complex CHD in neonates and young infants, with a low likelihood of need for additional diagnostic studies. The decreased risk by avoiding anesthesia must be balanced against the potential for adverse reactions with ferumoxytol.

There is great demand for high-throughput methods to characterize ligand affinity. By combining mRNA display with next-generation sequencing, we determined the kinetic on- and off-rates for over twenty thousand ligands, without the need for synthesis or purification of individual members. Our results are reproducible and as accurate as other methods of affinity measurement.

Inflammatory pseudotumor is a generic term used to designate a heterogeneous group of inflammatory mass-forming lesions histologically characterized by myofibroblastic proliferation with chronic inflammatory infiltrate. Inflammatory pseudotumor is multifactorial in etiology and generally benign, but it is often mistaken for malignancy given its aggressive appearance. It can occur throughout the body and is seen in all age groups. Inflammatory pseudotumor has been described in the literature by many organ-specific names, resulting in confusion. Recently within this generic category of inflammatory pseudotumor, inflammatory myofibroblastic tumor has emerged as a distinct entity and is now recognized as a fibroblastic/myofibroblastic neoplasm with intermediate biological potential and occurring mostly in children. We present interesting pediatric cases of inflammatory myofibroblastic tumors given this entity's tendency to occur in children. Familiarity and knowledge of the imaging features of inflammatory pseudotumor can help in making an accurate diagnosis, thereby avoiding unnecessary radical surgery.