Avascular necrosis of the vertebral body: MR imaging

Five patients with plain radiographic evidence of a compressed vertebra containing an intravertebral vacuum cleft indicative of avascular necrosis underwent magnetic resonance (MR) imaging. In these patients, the T2-weighted images revealed a distinct appearance consisting of marked and discrete hyperintensity at the location of the intravertebral cleft. T1-weighted images were hypointense in this region. Recognition of this pattern is important in the MR imaging evaluation of compression fractures of the vertebral body so that confusion with malignancy or infection may be avoided, thereby obviating additional diagnostic studies.     

Supraclinoid intracarotid chemotherapy using a flow-directed soft- tipped catheter

In an attempt to avoid toxic reactions of the eye as a complication of internal carotid arterial infusion of cisplatin, carmustine, or a combination of both for the treatment of brain tumors, a new Gore-Tex/Teflon coaxial catheter system has been used for supraclinoid placement. Catheter placement was successful in 14 of 16 attempts in eight patients. Two patients experienced eye pain and conjunctivitis--a result of the chemotherapeutic agent leaking through the Gore-Tex portion of the catheter at the infusion rate of 170 ml/h. No complications were noted as long as the infusion rate was maintained at 125 ml/h or lower.     

Breakpoint diversity illustrates distinct mechanisms for Robertsonian translocation formation

Robertsonian translocations are the most common chromosomal rearrangements in humans. The vast majority of the ten possible nonhomologous types of Robertsonian translocations ascertained are rob(13q14q) and rob(14q21q). Recombination between homologous sequences on nonhomologous chromosomes has been proposed as a mechanism leading to the preferential formation of rob(13q14q) and rob(14q21q). However, little evidence exists to indicate whether the remaining less common Robertsonian translocations form through a similar mechanism. To better elucidate the mechanisms involved in Robertsonian translocation formation, we have used fluorescence in situ hybridization to localize the breakpoints in 56 nonhomologous Robertsonian translocations. This study revealed highly variable locations of breakpoints in seven types of the less common Robertsonians, while nearly all rob(13q14q) and rob(14q21q) analyzed displayed breakpoints in the same locations. Therefore, this study provides direct evidence that rob(13q14q) and rob(14q21q) form through a specific mechanism, possibly involving homologous recombination, which is distinct from the mechanism(s) that contributes to the formation of the remaining types of Robertsonian translocations.      

Molecular refinement of the 1p36 deletion syndrome reveals size diversity and a preponderance of maternally derived deletions

The deletion of chromosome 1p36 is a newly recognized, relatively common contiguous gene deletion syndrome with a variable phenotype. The clinical features have recently been delineated and molecular analysis indicates that the prevalence of certain phenotypic features appears to correlate with deletion size. Phenotype/genotype comparisons have allowed the assignment of certain clinical features to specific deletion intervals, significantly narrowing the regions within which to search for candidate genes. We have extensively characterized the deletion regions in 30 cases using microsatellite markers and fluorescence in situ hybridization analyses. The map order of 28 microsatellite markers spanning the deletion region was obtained by a combination of genotypic analysis and physical mapping. The deletion region was divided into six intervals and breakpoints were found to cluster in mainly two regions. Molecular analysis of the deletions showed that two patients had complex re-arrangements; these cases shared their distal and proximal breakpoints in the two common breakpoint regions. Of the de novo deletions ( n = 28) in whichparental samples were available and the analysis was informative ( n = 27), there were significantly morematernally derived deletions ( n = 21) than paternally derived deletions ( n = 6) (chi1(2) = 8.35, P < 0.0001). Phenotype/genotype correlations and refinements of critical regions in our naturally occurring deletion panel have delineated specific areas in which to focus the search for the causative genes for the features of this syndrome.