Evaluation of MRI resolution affecting trabecular bone parameters: Determination of acceptable resolution

The objective of this study is to evaluate the effect of MR image resolution on trabecular bone parameters and to determine the acceptable resolution that can be accurately analyzed to assess structural parameters. Ten distal femoral condyle specimens of 1 × 1 × 1 cm³ were scanned with a 4.7‐T Bruker BioSpec MRI scanner using a three‐dimensional fast large‐angle spin‐echo sequence with various iso‐cubic voxels sizes (65, 130, 160, 196, 230, and 260 μm). Otsu thresholding was applied to identify voxels containing bone. Conventional bone parameters, structural bone parameters, and skeleton‐based local trabecular thickness (slTB.Th) were evaluated. The Bland–Altman method and correlation indicated that the conventional and structural bone parameters were preserved with an iso‐cubic voxel size up to 230 μm (r > 0.932 and r > 0.843, respectively). In addition, slTB.Th derived from the highest resolution images (65 μm iso‐cubic voxel size), correlated well (r > 0.833) with the values computed from lower resolution images, up to 230 μm, which is twice typical human trabecular thickness range (100–150 μm). The outcome of this study suggests that the various bone parameters were well preserved up to 230 μm images. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.     

Effects of epidural TNF-α inhibitor injection: analysis of the pathological changes in a rat model of chronic compression of the dorsal root ganglion

Objectives  

To evaluate the efficacy of a single direct epidural injection of tumor necrosis factor (TNF)-α inhibitor to reduce the pathological changes in nerve fiber injuries in a rat model of chronic compression of the dorsal root ganglion (CCD).     

Long-term follow-ups of revascularized immature necrotic teeth:three case reports

Revascularization of immature necrotic teeth is a reliable treatment alternative to conventional apexogenesis or apexification. In case 1,a 12-year-old boy had his necrotic,immature mandibular left second premolar treated with a revascularization technique. At a 24-month follow-up,periapical radiolucency had disappeared and thickening of the root wall was observed. In cases 2 and 3,a 10-year-old boy had his necrotic,immature,bilateral mandibular second premolars treated with the same modality. At 48-month (in case 2) and 42-month (in case 3) follow-ups,loss of periapical radiolucencies and increases in the root wall thickness were also observed.     

Evaluation of KCB-328, a new IKr blocking antiarrhythmic agent in pacing induced canine atrial fibrillation.

HYPOTHESIS: KCB-328 is a new potassium channel blocker, which prolongs action potential duration with exhibition of minimal reverse use dependence. We tested the efficacy and proarrhythmic potential of KCB-328, dofetilide and propafenone in the pacing induced canine model of atrial fibrillation (AF). METHODS: Mongrel dogs in complete heart block were paced for 1-6 weeks to produce AF, and given KCB-328 or dofetilide. A subset then received propafenone 14+/-3 days after testing the first drug. RESULTS: KCB-328 prolonged right and left atrial (RA and LA) activation times and AF cycle length (CL), terminating AF in 3 of 6 dogs. RA effective refractory period (ERP) and ventricular ERP and QT interval were prolonged. Dofetilide terminated AF in 1/6 dogs, and increased AF CL and ventricular ERP and QT interval. Dofetilide's reverse use dependency on the QT interval was greater than KCB-328. Propafenone prolonged RA and LA activation times and AF CL and terminated AF in 8 of 9 dogs. One death occurred with dofetilide, none with KCB-328 or propafenone. CONCLUSION: The spectrum of effect of the three drugs differed significantly: propafenone showed the greatest success in AF termination, and both propafenone and KCB-328 appeared less proarrhythmic than dofetilide in this model.     

Immobilization of urokinase on agarose matrices

Immobilization of urokinase, a plasminogen activator, was carried out to determine the effect of spacer length used on the immobilized enzyme activity. The enzyme was covalently coupled to agarose gel, both directly to the matrix and also via interposing different lengths of spacer groups. The specific activity of immobilized urokinase increased as the spacer length (n') increased to a certain length and tended to decrease thereafter. The maximal activity was shown when the value of n' was 7 for the agarose-NH-(CH2)n-CO-NH-(CH2)2-CO-NH-urokinase series. The coupling yield of the enzyme activity was from 33 to 68% depending on various forms of immobilized urokinase. The immobilized urokinase was characterized with regard to pH, temperature, storage, and thermal stabilities.     

Langerhans cell histiocytosis in a 5-month-old presenting with biparietal masses

Langerhans cell histiocytosis (LCH) is a rare proliferative disorder that occurs most commonly in the pediatric population as a result of pathological clonal proliferation of Langerhans cells with subsequent damage and destruction to surrounding tissue. Clinically, LCH presents in a variety of ways, which often results in prolonged time to diagnosis and subsequently poorer outcomes. In this case report, the authors describe an unusually early presentation of multisystem LCH in a patient at birth, which resulted in a 5-month delay to diagnosis and treatment. This patient presented both atypically young and with an uncommon initial manifestation of multisystem disease with multiple soft-tissue swellings rather than early skin involvement. Additionally, this patient had an unusual radiographic appearance with biparietal skull destruction on initial skull radiographs and biparietal soft-tissue lesions on CT resembling cephalohematoma at 3 months of age. The clinical and radiological evaluation, pathology, and treatment strategies are discussed, with particular attention paid to the importance of further workup of atypical nonresolving cephalohematomas to prevent disease progression and poorer outcomes.