A point mutation associated with a severe phenotype of neurofibromatosis 2

Neurofibromatosis 2 (NF2) is an autosomal dominant disease characterized by bilateral vestibular schwannomas and other nonmalignant tumors of the brain, spinal cord, and peripheral nerves. Although the average age of onset of NF2 is 20 years, some individuals may become symptomatic in childhood. We studied 5 unrelated NF2 patients who became symptomatic before age 13. All 5 had multiple tumors in addition to vestibular schwannoma, and none had a positive family history. Sequence analysis of the NF2 gene revealed identical nonsense mutation of exon 6 in 3 patients. Because this mutation destroys a restriction enzyme recognition site, genomic DNA from the 2 other children was directly tested for this change and identical alterations were detected. Although the work of our laboratory and others has not, in general, detected identical mutations in unrelated patients, this mutation seems to occur particularly frequently in the pediatric population and thus may be associated with an especially severe phenotype. Restriction analysis in children with NF2 may be a cost effective way of identifying their mutation. Further work is needed to characterize the effects of this change on the NF2 protein product and its relationship to this severe phenotype.     

Malignoma versus bacterial spondylodiscitis: value of spinal MRI for the differential diagnosis in an emergency situation. Description in an acute case with progressive paraplegia

BACKGROUND: For the radiation oncologist in an emergency situation with acute progressive paraplegia distinguishing between benign versus malignant vertebral compression fracture without known malignoma may cause a severe diagnostic problem, when a rapid therapeutic decision is required. PATIENT AND METHOD: A case of an elderly diabetic patient with acute onset of a progressive neurologic deficit is reported. No malignancy was known so far. The CT of the spine showed a destruction of the 7th and 8th thoracic vertebral body with compression of the spinal cord. The patient was referred to the radiotherapist for radiation of a presumed malignant spinal process. RESULT: For differential diagnosis a magnetic resonance imaging (MRI) of the spine was performed and could lead to the correct diagnosis of an infectious spondylodiscitis. CONCLUSION: The MRI of the spine has a potential role for correct differentiation between benign and malignant spinal lesions and may thereby assist the radiotherapist in the decision making in an emergency situation.     

Contribution of listeners' approaching motion to auditory distance perception.

Of the several sources of acoustic information for distance perception, those arising from motion of the listener or sound source have received little attention. This motion-related information (recently called acoustic tau) is described, and experiments evaluating its utilization are presented. Accuracy and consistency at walking to the locations of briefly presented sounds were better when people listened while walking than while standing still. Manipulations of the sound to simulate shorter or longer target distances produced appropriate undershooting but not overshooting. The results indicate that people use motion-related acoustic information about distance to guide their locomotor actions, although they do not take full advantage of this information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Growth rate and surface microstructure in α(6H)–SiC thin films grown by chemical vapor deposition

Monocrystalline 6H-SiC thin films have been epitaxially grown on off-axis 6H-SiC {0001} substrates in the temperature range of 1623–1873 K via chemical vapor deposition. The growth rate was a strong function of the growth temperature and the reactant gas concentration. The activation energies for growth were 64 kJ/mole and 55 kJ/mole for the (0001) Si face and the (0001) C face, respectively. The concentration of growth pits in the films increased as a function of decreasing deposition temperature, increasing concentration of reactant gases and increasing off-axis orientation. Beta-SiC islands were also observed in the epilayers when the (SiH₄ + C₂H₄)/H₂ ratio was ≥2.5:3000.