Neural control of bone metabolism and growth has been suggested, although the identity of participating neurons and neurotransmitters effecting this control has not been established. Immunohistochemical studies demonstrated a system of vasoactive intestinal peptide (VIP)-immunoreactive nerve fibers that innervate periosteum and bone in several mammalian species. Thoracic sympathetic chain ganglionectomy resulted in an ipsilateral loss of VIP-immunoreactive fibers in the periosteum of ribs, whereas dorsal root ganglionectomy had no effect. Injection of fast blue into rib periosteum labeled a population of VIP-immunoreactive sympathetic postganglionic neurons. Thus, postganglionic sympathetic neurons may provide an important means by which VIP regulates bone mineralization.

A new type of endovascular prosthesis has been developed using a unique metal alloy (nitinol) with a heat-sensitive memory. Nitinol wire coil grafts were straightened in ice water and passed into the canine aorta via catheter, where they reformed into their original shapes. Follow-up aortograms demonstrated long-term patency with minimal thrombus formation. Nitinol endovascular coil grafts may eventually be used in the nonsurgical treatment of several forms of vascular disease.

Restoration of femoral offset is an important part of total hip arthroplasty. Since radiographs showing the femur at a sufficient degree of internal rotation to allow direct measurement of femoral offset are not usually available, templates of the prosthesis at 25 and 45 degrees of rotation were created. Radiographs of 20 cadaver femurs with a mean offset of 44 +/- 5 mm (r 36-56) were then obtained at different degrees of rotation. Simple guidelines to indicate the correct template for each projection of the femur were found. The system could be used to select a prosthesis with correct offset using radiographs obtained at angles of rotation between 20 degrees internally and 40 degrees externally.

Purpose: The stiffness of a myocardial infarct affects the left ventricular pump function and remodeling. Magnetic resonance elastography (MRE) is a noninvasive imaging technique for measuring soft-tissue stiffness in vivo. The purpose of this study was to investigate the feasibility of assessing in vivo regional myocardial stiffness with high-frequency 3D cardiac MRE in a porcine model of myocardial infarction, and compare the results with ex vivo uniaxial tensile testing. Methods: Myocardial infarct was induced in a porcine model by embolizing the left circumflex artery. Fourteen days postinfarction, MRE imaging was performed in diastole using an echocardiogramgated spin-echo echo-planar-imaging sequence with 140-Hz vibrations and 3D MRE processing. The MRE stiffness and tensile modulus from uniaxial testing were compared between the remote and infarcted myocardium. Results: Myocardial infarcts showed increased in vivo MRE stiffness compared with remote myocardium (4.6 6 0.7 kPa versus 3.0 6 0.6 kPa, P ¼ 0.02) within the same pig. Ex vivo uniaxial mechanical testing confirmed the in vivo MRE results, showing that myocardial infarcts were stiffer than remote myocardium (650 6 80 kPa versus 110 6 20 kPa, P ¼ 0.01).Conclusions: These results demonstrate the feasibility of assessing in vivo regional myocardial stiffness with highfrequency 3D cardiac MRE. Magn Reson Med 79:361-369, 2018. V C 2017 International Society for Magnetic Resonance in Medicine.

In this study, rivaroxaban was more effective than enoxaparin for short-term thromboprophylaxis of mechanical valve prosthetics in the heterotopic aortic position. It reduced valve thrombus and platelet deposition on day 30 following implantation without increased adverse events. Future studies would provide additional support for clinical trials evaluating rivaroxaban as an alternative to warfarin for appropriately selected patients with prosthetic aortic valves.