Differential diagnosis of pediatric tumors of the nasal cavity and paranasal sinuses: a 45-year multi-institutional review

We conducted a retrospective case-series review to identify the various diagnoses of neoplasms of the nasal cavity and paranasal sinuses in a pediatric population. Our study group was made up of 54 children-23 boys and 31 girls, aged 8 months to 16 years (mean: 9 yr). All patients had been diagnosed with a tumor of the nasal cavity or paranasal sinuses between Jan. 1, 1955, and Dec. 31, 1999, at one of four university-based, tertiary care referral centers. We compiled data on tumoral characteristics (location, size, and histopathology), morbidity and mortality, and rates of recurrence. Lesions included adnexal neoplasm, ameloblastic fibro-odontoma, basal cell carcinoma, benign fibrous histiocytoma, blue nevus, chondrosarcoma, compound nevus, epithelioma adenoides cysticum, esthesioneuroblastoma, Ewing sarcoma, fibrosarcoma, giant cell granuloma, granulocytic sarcoma, hemangioma, hemangiopericytoma, Langerhans cell histiocytosis, lymphangioma, lymphoma, melanoma, neuroblastoma, neurofibroma, ossifying osteofibroma, osteochondroma, osteosarcoma, port wine stain, rhabdomyosarcoma, Spitz nevus, and xanthogranuloma. To the best of our knowledge, this is the largest such study of its kind to date. We believe that the large size of this study and the data on disease incidence will allow clinicians to be better informed of the differential diagnosis of neoplasms of the nasal cavity and paranasal sinuses in the pediatric population.     

Influenza virus M2 integral membrane protein is a homotetramer stabilized by formation of disulfide bonds

The oligomeric structure of the influenza A virus M2 integral membrane protein was determined. On SDS-polyacrylamide gels under nonreducing conditions, the influenza A/Udorn/72 virus M2 forms disulfide-linked dimers (30 kDa) and tetramers (60 kDa). Sucrose gradient analysis and chemical cross-linking analysis indicated that the oligomeric form of M2 is a tetramer consisting of either a pair of disulfide-linked dimers or disulfide-linked tetramers. In addition, a small amount of a cross-linked species of 150-180,000 kDa, which the available data suggest contains only M2 polypeptides, was observed. The role of M2 cysteine residues in disulfide bond formation and their role in forming oligomers were examined by converting each of the two extracellular and single cytoplasmic cysteine residues to serine residues and expressing the altered M2 proteins in eukaryotic cells. Removal of either one of the N-terminal cysteines at residues 17 or 19 indicated that tetramers formed that consisted of a pair of noncovalently associated disulfide-linked dimers, suggesting that each of the cysteine residues is equally competent for forming disulfide bonds. When both cysteine residues were removed from the M2 N-terminal domain, no disulfide-linked forms were observed. When solubilized in detergent this double-cysteine mutant lost reactivity with a M2-specific mAb and exhibited an altered sedimentation pattern on sucrose gradients. However, chemical cross-linking of this double-cysteine mutant in membranes indicated that it can form tetramers. Taken together, these data suggest that disulfide bond formation, although not essential for oligomeric assembly, stabilizes the M2 tetramer from disruption by detergent solubilization.     

家庭医生的一天

诊断复发性尿路感染患者时，尿液培养至关重要。