Gadolinium Deposition and Nephrogenic Systemic Fibrosis: A Radiologist's Primer.

Gadolinium-based contrast agents (GBCAs) have an excellent safety profile. However, over the last 2 decades, two specific concerns have surfaced. GBCAs are associated with nephrogenic systemic fibrosis (NSF) and tissue retention of gadolinium. NSF is a rare fibrosing disorder with a poor prognosis, which is characterized by skin and subcutaneous thickening as well as systemic manifestations. The disease has been reported exclusively in patients with advanced renal disease, and it is associated with higher doses and specific types of GBCAs. The number of new cases of NSF has fallen over the past decade, presumably because of adherence by health care providers to regulatory guidelines, which continue to evolve. While gadolinium retention has been known to occur in the liver and bones, the relatively recent findings of deposition and retention in the brain have reignited the debate concerning the safety profile of GBCAs. Despite these concerns, there have been no proven health effects related to gadolinium deposition and retention other than NSF. The authors review the different categories of GBCAs available for commercial use, discuss NSF and gadolinium retention in the brain, and provide updates on the latest U.S. and European regulatory guidelines regarding use of these agents. Given the frequency with which GBCAs are used in clinical practice, it is imperative for all radiologists to learn the current guidelines to provide the safest and highest quality of patient care. ©RSNA, 2019.

Regulating the Basicity of Metal-Oxido Complexes with a Single Hydrogen Bond and Its Effect on C-H Bond Cleavage.

The functionalization of C-H bonds is an essential reaction in biology and chemistry. Metalloenzymes that often exhibit this type of reactivity contain metal-oxido intermediates that are directly involved in the initial cleavage of the C-H bonds. Regulation of the cleavage process is achieved, in part, by hydrogen bonds that are proximal to the metal-oxido units, yet our understanding of their exact role(s) is still emerging. To gain further information into the role of H-bonds on C-H bond activation, a hybrid set of urea-containing tripodal ligands has been developed in which a single H-bond can be adjusted through changes in the properties of one ureayl N-H bond. This modularity is achieved by appending a phenyl ring with different para-substituents from one ureayl NH group. The ligands have been used to prepare a series of MnIII-oxido complexes, and a Hammett correlation was found between the pKa values of the complexes and the substituents on the phenyl ring that was explained within the context of changes to the H-bonds involving the MnIII-oxido unit. The complexes were tested for their reactivity toward 9,10-dihydroanthracene (DHA), and a Hammett correlation was found between the second-order rate constants for the reactions and the pKa values. Studies to determine activation parameters and the kinetic isotope effects are consistent with a mechanism in which rate-limiting proton transfer is an important contributor. However, additional reactivity studies with xanthene found a significant increase in the rate constant compared to DHA, even though the substrates have the same pKa(C-H) values. These results do not support a discrete proton-transfer/electron-transfer process, but rather an asynchronous mechanism in which the proton and electron are transferred unequally at the transition state.

Modulating the Primary and Secondary Coordination Spheres within a Series of CoII-OH Complexes.

The interplay between the primary and secondary coordination spheres is crucial to determining the properties of transition metal complexes. To examine these effects, a series of trigonal bipyramidal Co-OH complexes have been prepared with tripodal ligands that control both coordination spheres. The ligands contain a combination of either urea or sulfonamide groups that control the primary coordination sphere through anionic donors in the trigonal plane and the secondary coordination sphere through intramolecular hydrogen bonds. Variations in the anion donor strengths were evaluated using electronic absorbance spectroscopy and a qualitative ligand field analysis to find that deprotonated urea donors are stronger field ligands than deprotonated sulfonamides. Structural variations were found in the CoII-O bond lengths that range from 1.953(4) to 2.051(3) Å; this range in bond lengths were attributed to the differences in the intramolecular hydrogen bonds that surround the hydroxido ligand. A similar trend was observed between the hydrogen bonding networks and the vibrations of the O-H bonds. Attempts to isolate the corresponding CoIII-OH complexes were hampered by their instability at room temperature.

Unprecedented gallium-nitrogen anions: synthesis and characterization of [(Cl3Ga)3N]3- and [(Cl3Ga)2NSnMe3]2-.

The [(Cl3Ga)3N](3-) (1) anion, which is the sole example of a discrete chemical species containing a µ3-N atom bound only to gallium, was isolated from the reaction of Cl3Ga·N(SnMe3)3 with [GaCl4](1-). The analogous reaction of [GaCl4](1-) with (Me3Sn)3N afforded [(Cl3Ga)2NSnMe3](2-) (2), which is also an unprecedented anion containing a single µ3-N atom bound to only gallium and tin.

Intrawound vancomycin powder reduces surgical site infections in posterior cervical fusion.

STUDY DESIGN: Retrospective comparative study using prospectively collected data. OBJECTIVE: To compare the rate of infection with and without the use of vancomycin powder application during posterior cervical instrumentation. SUMMARY OF BACKGROUND DATA: Surgical site infections (SSI) are a significant source of morbidity in multilevel posterior-instrumented fusions for cervical spondylotic myelopathy (CSM). Local delivery of antibiotics has been associated with decreased rates of SSI in posterior-instrumented fusions, but no study has addressed the effects of these measures on a population composed of exclusively multilevel posterior cervical instrumentation performed with decompression for CSM. METHODS: All patients undergoing multilevel posterior decompression and instrumentation for CSM by a single surgeon from 2003-2011 were included. Post hoc analysis of prospectively collected data was analyzed comparing consecutive patients treated without the use of vancomycin powder with those treated after the initiation of vancomycin powder prophylaxis. Intervention cohort and controls were examined for differences in SSI rate, body mass index, neurological status, comorbidities, and complications. RESULTS: A total of 112 patients were included in the study. Intervention (n = 40) and control (n = 72) groups were statistically similar with regard to age, body mass index, comorbidities, estimated blood loss, and operative time. Univariate analysis showed a significant decrease in infection rate in the intervention group (0%) compared with the control group (15%) in this high-risk population (P = 0.007; power = 81%). No adverse events were noted in the intervention group associated with the use of vancomycin powder. CONCLUSION: The local application of vancomycin was associated with a significant reduction in the risk of SSI in multilevel posterior cervical-instrumented fusions for CSM. This study supports the growing body of evidence that vancomycin powder placed in the wound can reduce the incidence of postoperative wound infections, and is the first that addresses this specific population. LEVEL OF EVIDENCE: 2.

The motive for sensory pleasure: enjoyment of nature and its representation in painting, music, and literature.

Eight studies assessed the motive for sensory pleasure (MSP) involving a general disposition to enjoy and pursue pleasant nature-related experiences and avoid unpleasant nature-related experiences. The stated enjoyment of pleasant sights, smells, sounds, and tactile sensations formed a unitary construct that was distinct from sensation seeking, novelty preference, and need for cognition. MSP was found to be related to (a) enjoyment of pleasant nature scenes and music of high but not low clarity; (b) enjoyment of writings that portrayed highly detailed nature scenes; (c) enjoyment of pleasantly themed paintings and dislike of unpleasant paintings, as distinct from findings with Openness to Experience; (d) choice of pleasant nature scenes over exciting or intellectually stimulating scenes; (e) view duration and memory of artistically rendered quilts; (f) interest in detailed information about nature scenes; and (g) frequency of sensory-type suggestions for improvement of a museum exhibit.