Automatic plaque characterization employing quantitative and multicontrast MRI.

Multicontrast magnetic resonance imaging (MRI) has shown promise in identifying and characterizing atherosclerotic plaques. One of the limitations of this technique is the lack of a practical automated plaque characterization scheme. In the current study, a prior-information-enhanced clustering (PIEC) technique that utilizes both multicontrast MR images and quantitative T(2) maps is proposed to characterize atherosclerotic plaque components automatically. The PIEC algorithm was assessed on computationally simulated images and multicontrast MRI data of coronary arteries. Multicontrast (T(1)-, T(2)-, partial T(2)-, and proton density-weighted) MR images were acquired from freshly excised human coronary arteries using a 4.7T small-animal scanner. The T(2) distribution for each plaque constituent was measured by exponentially fitting the signal from multiple MR images with different TEs and the same TR. The calculated T(2) distributions were used as the a priori information and combined with the Fuzzy C-Means (FCM)-based clustering algorithm to characterize plaque constituents. The proposed PIEC technique appears to be a promising algorithm for accurate automated plaque characterization.     

Normalization by dietary cod-liver oil of reduced thrombogenesis in essential fatty acid deficient rats

Rats, deficient in essential fatty acids (EFA), were given diets containing 5 energy% sunflowerseed oil (SO, rich in linoleic acid), cod-liver oil (CLO, rich in timnodonic acid and cervonic acid), or hydrogenated coconut oil (HCO), containing no EFAs at all. SO and CLO feeding resulted in normalization of the reduced arterial thrombus formation in EFA-deficient animals. SO feeding was associated with the normalization of the arachidonic acid content of platelet phospholipids. CLO feeding did not have this effect but greatly increased the availability of timnodonic acid (EPA) and cervonic acid (DHA). Further research is required to investigate whether these changes in fatty acid composition can be hold responsible for the normalizing effect of dietary CLO on the disturbed arterial thrombosis tendency in EFA deficient rats, possibly via the formation of eicosanoids.     

Evidence against a lymphocyte-mediated autoimmune etiology for murine muscular dystrophy

The hypothesis that murine muscular dystrophy (MMD) is a lymphocyte-mediated autoimmune disease was tested by orthotopically transplanting normal and dystrophic muscle into normal or dystrophic hosts immunosuppressed with antilymphocyte serum (ALS). Normal serum (NS)-treated animals served as controls. Allograft conditions revealed that both normal and dystrophic muscle were antigenic and were rejected by NS-treated hosts, with the myofiber component of the muscle implant being rejected before the fibroblast portion. New muscle regenerated in a host receiving ALS therapy and was retained by the host until 30 days after the withdrawal of the ALS therapy. Normal muscle isografted into dystrophic hosts regenerated irrespective of whether the host was treated with ALS or NS. In the reciprocal experiment, dystrophic muscle regenerated in normal hosts, but the myofibers were gradually eliminated and replaced by connective tissue, thus behaving as they would have in the donor animal. These observations are incompatible with a lymphocyte-mediated autoimmune etiology for MMD. Furthermore, they raise some question about the claims of muscular dystrophy being attributable to a neural or vascular lesion, and imply that the lesion may be intrinsic to the muscle.     

Shivering following retrobulbar block

A case of a severe but brief period of shivering following a retrobulbar block (RBB) is presented. The shivering occurred within two minutes after completion of the RBB and subsided gradually within five minutes, without specific treatment. The patient remained conscious during the episode of shivering. The shivering was so abrupt and severe as to be misjudged as a seizure, but its onset appeared to be slower than a seizure. The mechanism of shivering appeared to be the central spread of local anaesthetic solution into the brain stem, along the optic nerve. Shivering may be a warning sign of brain stem anaesthesia and demands special care to anticipate life-threatening complications.     

Comparison of immunoscintigraphy, efficacy, and toxicity of conventional and pretargeted radioimmunotherapy in CD20-expressing human lymphoma xenografts.

Pretargeted radioimmunotherapy (RIT) using streptavidin (sAv)-conjugated antibodies before radiolabeled-biotin is a promising approach to improve absorbed dose ratios and achieve high durable remission rates with diminished systemic toxicity. This study compared the immunoscintigraphy, toxicity, and therapeutic efficacy of pretargeted RIT with conventional RIT using an anti-CD20 antibody. METHODS: Athymic mice bearing Ramos human Burkitt's lymphoma xenografts were injected intraperitoneally with a 1F5-sAv conjugate followed 24 h later by a galactosylated, biotinylated clearing agent (CA) and, finally, 3 h later by (111)In- or (90)Y-labeled 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-biotin. The comparison groups consisted of mice injected with conventional, directly labeled (111)In- or (90)Y-1F5. RESULTS: Rapid tumor uptake of radioactivity within 2 h was observed with the pretargeting approach, resulting in high-contrast tumor images at 24 h with minimal blood-pool radioactivity. Although conventional radiolabeled antibodies produced clear tumor images at 24 h, a large amount of radioactivity was present in the blood pool. The tumor-to-blood ratio was 3.5:1 with pretargeting compared with 0.4:1 with conventional (111)In-1F5. Pretargeted RIT with 29.6 MBq (800 micro Ci) (90)Y-DOTA-biotin cured 100% of mice with tolerable toxicity, whereas conventional RIT with (90)Y-1F5 at a dose of 14.8 MBq (400 micro Ci) produced no cures, induced profound pancytopenia, and was lethal to all mice. CONCLUSION: These results suggest that anti-CD20 pretargeted RIT may be superior to conventional radiolabeled antibodies in terms of radioimmunoscintigraphy, toxicity, and therapeutic efficacy for treatment of B-cell lymphomas.