High-resolution vascular imaging of the rat spine using liposomal blood pool MR agent

BACKGROUND AND PURPOSE: High-resolution, vascular MR imaging of the spine region in small animals poses several challenges. The small anatomic features, extravascular diffusion, and low signal-to-noise ratio limit the use of conventional contrast agents. We hypothesize that a long-circulating, intravascular liposomal-encapsulated MR contrast agent (liposomal-Gd) would facilitate visualization of small anatomic features of the perispinal vasculature not visible with conventional contrast agent (gadolinium-diethylene-triaminepentaacetic acid [Gd-DTPA]). METHODS: In this study, high-resolution MR angiography of the spine region was performed in a rat model using a liposomal-Gd, which is known to remain within the blood pool for an extended period. The imaging characteristics of this agent were compared with those of a conventional contrast agent, Gd-DTPA. RESULTS: The liposomal-Gd enabled acquisition of high quality angiograms with high signal-to-noise ratio. Several important vascular features, such as radicular arteries, posterior spinal vein, and epidural venous plexus were visualized in the angiograms obtained with the liposomal agent. The MR angiograms obtained with conventional Gd-DTPA did not demonstrate these vessels clearly because of marked extravascular soft-tissue enhancement that obscured the vasculature. CONCLUSIONS: This study demonstrates the potential benefit of long-circulating liposomal-Gd as a MR contrast agent for high-resolution vascular imaging applications.     

MOSFET dosimetry for radiation dose assessment of bismuth shielding of the eye in children

OBJECTIVE: The purpose of our study was to measure radiation dose to the orbit during pediatric cranial CT with and without bismuth shielding using a novel dosimetry system. Cranial CT was performed on a pediatric anthropomorphic phantom, with and without bismuth eye shields. A solid-state metal oxide semiconductor field effect transistor (MOSFET) dosimeter was used to obtain real-time dose measurements. CONCLUSION: Bismuth shielding reduced radiation dose to the eye by up to 42%; shield artifact fell outside the diagnostic area of interest.     

Allogene Gesichtstransplantation: Fiktion oder Realität?

BACKGROUND: The aim of this study was to describe two methods of face-harvesting techniques -- a skin and soft tissue flap and a combined osteocutaneous flap -- and to demonstrate the compatibility between donor and recipient in a human fresh cadaver model. METHODS: In fresh human cadavers the skin and soft tissue of the face (type 1) and a combined osteocutaneous flap (including a le Fort III segment, type 2) were harvested. The faces were subsequently exchanged among the donor crania, simulating full-face transplantation. RESULTS: Both flaps are based on the external blood supply of the faciotemporal vessels and the external jugular vein. The end branches of the trigeminal nerve could potentially be used for restoration of sensation (type 1 flap). With type 2 flaps the facial expression may be restored with the inclusion of the facial nerve. Four morphological parameters determine the donor/recipient compatibility: skin color and texture, anthropometric head dimensions, specific soft tissue components (nose, lip, cheek, and eyebrow), and gender. CONCLUSION: Apart from ethical considerations, long-term immunosuppression will remain the limiting factor of full facial transplantation in the near future.     

17-beta estradiol independently regulates erythropoietin synthesis and NOS activity during hypoxia

We reported previously that 17-beta estradiol (E2-beta) attenuates hypoxic induction of erythropoietin (EPO) synthesis in rats. We hypothesized this attenuation is mediated by increased nitric oxide (NO) bio-availability. To investigate this hypothesis, ovariectomized estrogen-depleted rats were instrumented with arterial and venous catheters and treated with either E2-beta (20 microg/24 hrs) or vehicle (polypropylene glycol) for 7 days. Rats were placed in Plexiglas boxes and administered a bolus of either the NO synthase inhibitor, Nomega-nitro-L-arginine (l-NNA, 15 mg/kg) or saline. Following this bolus, saline or l-NNA was continuously infused (15 mg/kg/h) throughout the 8 hours of hypoxic exposure (12% O2). Hypoxia increased plasma NO metabolites (NOx) in both saline groups but more in E2-beta-treated rats. l-NNA prevented this increase in both groups. Renal endothelial NO synthase (NOS) expression was unaltered by hypoxia, l-NNA, or E2-beta. Despite preventing increases in plasma NOx during hypoxia, l-NNA did not affect E2-beta attenuation of EPO synthesis. We conclude that E2-beta independently attenuates hypoxic induction of EPO and augments hypoxic increases in NO synthesis.     

Assessing patient utilities for varying degrees of low back pain

RATIONALE AND OBJECTIVES: We sought to quantify patient preferences for mild, moderate, and severe low back pain via time-tradeoff analysis and utility measurement. MATERIALS AND METHODS: Forty-one patients being treated for low back pain in a tertiary care teaching hospital participated in the study. Patients were asked to decide which of three health states they were currently experiencing as well as which of the three health states was the worst experienced during their lifetime. A time-tradeoff analysis was performed, during which patients were asked the amount of time in each of the health states they would exchange for complete resolution of symptoms. We correlated (1) subjects' current health state with reported utility and (2) degree of previous low back pain with results of time-tradeoff measurements. RESULTS: All patients were willing to trade a greater number of life-years for resolution of symptoms given a more severe perceived health state. Utility decreased as severity of back pain scenarios increased, with an average utility of 0.93 +/- 0.11 for mild, 0.65 +/- 0.21 for moderate, and 0.18 +/- 0.17 for severe pain. No significant difference in time-tradeoff among subjects was identified based upon current health state on the day of interview. A statistically significant difference was seen in patients' willingness to trade time among those who had actually experienced severe pain versus those who had not. Kendall's correlation revealed that subjects who had experienced severe back pain exhibited significantly lower utilities (P < 0.01) compared with subjects who had never experienced severe pain. CONCLUSIONS: As expected, patients with severe low back pain were willing to sacrifice more potential years of life for resolution of symptoms, suggesting time-tradeoff can accurately reflect patient utility. 2. However, we found no correlation between a subject's current health state and reported utility.     

Perianal fistulae caused by Mycobacterium fortuitum

Mycobacterium fortuitum is a rapidly growing Mycobacterium , which usually colonizes the soil, dust and water. It commonly causes skin and soft tissue infections especially in patients who have preceding trauma. We report a case of perianal fistulae caused by M. fortuitum.     

Single coronary artery from the left sinus with atherosclerosis

We report a rare case of a single coronary artery originating from the left sinus of Valsalva with extensive atherosclerosis in a patient presenting with unstable angina. The distal circumflex artery continued the course of the right coronary artery.     

The role of semantic complexity in treatment of naming deficits: training semantic categories in fluent aphasia by controlling exemplar typicality.

The effect of typicality of category exemplars on naming was investigated using a single subject experimental design across participants and behaviors in 4 patients with fluent aphasia. Participants received a semantic feature treatment to improve naming of either typical or atypical items within semantic categories, while generalization was tested to untrained items of the category. The order of typicality and category trained was counterbalanced across participants. Results indicated that patients trained on naming of atypical exemplars demonstrated generalization to naming of intermediate and typical items. However, patients trained on typical items demonstrated no generalized naming effect to intermediate or atypical examples. Furthermore, analysis of errors indicated an evolution of errors throughout training, from those with no apparent relationship to the target to primarily semantic and phonemic paraphasias. Performance on standardized language tests also showed changes as a function of treatment. Theoretical and clinical implications regarding the impact of considering semantic complexity on rehabilitation of naming deficits in aphasia are discussed.     

The role of semantic complexity in treatment of naming deficits: training semantic categories in fluent aphasia by controlling exemplar typicality.

The effect of typicality of category exemplars on naming was investigated using a single subject experimental design across participants and behaviors in 4 patients with fluent aphasia. Participants received a semantic feature treatment to improve naming of either typical or atypical items within semantic categories, while generalization was tested to untrained items of the category. The order of typicality and category trained was counterbalanced across participants. Results indicated that patients trained on naming of atypical exemplars demonstrated generalization to naming of intermediate and typical items. However, patients trained on typical items demonstrated no generalized naming effect to intermediate or atypical examples. Furthermore, analysis of errors indicated an evolution of errors throughout training, from those with no apparent relationship to the target to primarily semantic and phonemic paraphasias. Performance on standardized language tests also showed changes as a function of treatment. Theoretical and clinical implications regarding the impact of considering semantic complexity on rehabilitation of naming deficits in aphasia are discussed.