Pituitary fossa: chemical shift effect in MR imaging

The effect of chemical shift on magnetic resonance (MR) imaging of the pituitary fossa was studied. Healthy volunteers underwent conventional MR imaging of the pituitary fossa and then imaging with the frequency-encoding gradient reversed or with the phase- and frequency-encoding gradients interchanged. Comparison of the image pairs in each subject showed that the thin, black stripe evident at the water-fat interface within the pituitary fossa was altered when the gradients were changed. Therefore, the low-intensity signal within the pituitary fossa is a chemical shift misregistration effect.     

Anulus fibrosus in bulging intervertebral disks

In this investigation the association of radial tears of the anulus fibrosus and bulging of the intervertebral disk was studied. An index of disk bulging was measured in sagittal anatomic sections in 149 lumbar disks from 31 cadavers. The indexes of disk bulging were correlated with stages of disk development and the presence of an annular tear. The largest disk-bulging indexes were always associated with radial tears of the anulus. Eighty-four percent of the disks with radial tears had disk-bulging indexes greater than 2.5 mm. Most normal adult disks had an index of less than 2.5 mm. The results challenge the concept that the anulus fibrosus is intact in bulging disks, although ruptured in herniated disks.     

Osteopetrosis: MR characteristics at 1.5 T

Four patients with proved osteopetrosis (three with the infantile malignant form and one with the benign form) were examined with magnetic resonance imaging at 1.5 T. All patients were studied in the coronal and sagittal planes using both short and long repetition time/echo time sequences. The infantile malignant form was characterized by a complete lack of signal from the marrow alternating with a signal intensity equivalent to that of the intervertebral disks, resulting in a "stepladder" appearance. In the benign form or after successful marrow transplantation in the infantile malignant form, intermediate or high signal intensity in the vertebrae was noted, suggesting the presence of some marrow elements.     

Biopharmaceutics and pharmacokinetics of 5-phenyl-1, 2-dithiole-3-thione complexed with sulfobutyl ether-7-beta-cyclodextrin in rabbits.

The biopharmaceutics and pharmacokinetics of 5-phenyl-1, 2-dithiole-3-thione (5PDTT) were investigated in rabbits, after administration as a complex with sulfobutyl-ether-7-beta-cyclodextrin (SBE7-beta-CD) by intravenous and oral routes and as a micronized powder by oral route. 5PDTT had a rapid and large red blood cell partitioning that was not dependent on drug concentration either in vitro or ex vivo. The blood clearance was very high (354 +/- 131 mL/min) suggesting extrahepatic metabolism and/or nonrenal elimination and a significant volume of distribution (67 +/- 76 L). The renal clearance was 0.17% of total clearance. 5-phenyl-1,2-dithiol-3-one (5PDTO) was identified as a metabolite in blood and urine. The bioavailability of 5PDTT following administration of 5PDTT/SBE7-beta-CD complex was estimated to 41% while it was close to zero when 5PDTT was given as a micronized powder.     

Expression of rat insulin-like growth factor binding protein-6 in the brain, spinal cord, and sensory ganglia

Insulin-like growth factors (IGFs) are important trophic factors during development as well as in the adult or damaged nervous system. Their trophic actions are modulated by interactions with six distinct IGF binding proteins. The mRNA expression profiles of binding proteins 2, 4 and 5 in the normal developing and adult CNS are well characterized and are shown to have distinctive, non-overlapping distributions. The IGF binding protein-6 (BP6) is also expressed in the CNS, however, details regarding its mRNA expression distribution in the developing and adult nervous system is limited. BP6 has the unique property of preferentially binding the IGF-II ligand. Coupled with the fact that this ligand is the most abundantly expressed IGF in the adult CNS, this suggests that the IGF-II/BP6 complex has a unique role in modulating IGF-II function in the adult brain. In this report the anatomical distribution of BP6 messenger RNA in the developing and adult rat nervous system is presented. In the embryonic animal the CNS expression is tightly restricted to trigeminal ganglia and, relative to the rest of the embryo, this structure has the highest expression. The expression in the forebrain and cerebellum does not occur until after postnatal day 21 and then is primarily associated with GABAergic interneurons. The highest levels of expression in the adult animal are in the hindbrain, spinal cord, cranial ganglia, and dorsal root ganglia. These nuclei in the hindbrain and periphery that express BP6 are all associated with the coordination of sensorimotor function in the cerebellum, which indicates an important role for the BP6/IGF-II complex in the function and maintenance of these systems.