Regulation of MYCN expression in human neuroblastoma cells

Background  

Amplification of the MYCN gene in neuroblastoma (NB) is associated with a poor prognosis. However, MYCN -amplification does not automatically result in higher expression of MYCN in children with NB. We hypothesized that the discrepancy between MYCN gene expression and prognosis in these children might be explained by the expression of either MYCN-opposite strand (MYCNOS) or the shortened MYCN-isoform (ΔMYCN) that was recently identified in fetal tissues. Both MYCNOS and ΔMYCN are potential inhibitors of MYCN either at the mRNA or at the protein level.     

Western Australian cigarette smokers have fewer small lung nodules than North Americans on CT screening for lung cancer

To determine the prevalence of small lung nodules on low‐dose helical computed tomography (CT) in a Western Australian cohort of asymptomatic long‐term cigarette smokers and to compare this with a large, similarly derived cohort of North Americans from the Mayo Clinic Lung Cancer Screening Trial. Forty‐nine asymptomatic long‐term cigarette smokers of minimum age 50 years underwent a low‐dose 64‐slice helical CT of the lungs. Images were viewed on a soft copy reporting station with thin section axial and coronal images, maximum intensity projection images, and advanced image manipulation tools. The prevalence of all nodules was 39%, significantly lower than the Mayo Clinic cohort prevalence of 51% (P < 0.01, Fisher's exact test), despite the use of more advanced imaging technology and image manipulation designed to increase the sensitivity for nodules. The prevalence of small nodules in asymptomatic long‐term cigarette smokers in Western Australia is high, though significantly less than that found in a large study in North America. The authors postulate this is due to the relatively low rates of mycobacterium tuberculosis and soil‐derived fungal pulmonary infections in Western Australia, as well as a lower degree of urban air pollution.     

Cyclin D1 protein analysis in the diagnosis of mantle cell lymphoma

Mantle cell lymphoma (MCL) is a clinicopathologic entity that is difficult to diagnose on histopathologic criteria. Approximately 50% to 70% of MCL contain a t(11;14)(q13;q32) translocation involving the cyclin D1 gene. Irrespective of this rearrangement, almost all MCL show overexpression of the cyclin D1 gene at the mRNA level. Other B-cell non-Hodgkin's lymphomas (NHL) do not show this rearrangement or overexpression of cyclin D1. We developed an immunohistochemical assay to detect overexpression of the cyclin D1 protein on conventional formalin-fixed, paraffin-embedded biopsies using the well-defined monoclonal antibody DCS-6. Expression in tumor cells was compared with expression of cyclin D1 in endothelial cells and fibroblasts. An exclusively nuclear staining pattern was observed. Moreover, expression was directly compared with the expression observed by immunoblot analysis with the same antibody, as well as with mRNA expression and with the occurrence of genomic rearrangements within the BCL-1 locus. Of 13 MCL that were analyzed by immunohistochemistry and immunoblot, 12 showed overexpression with both techniques, whereas no overexpression was observed in 39 other NHL. Of 13 additional MCL studied either by immunohistochemistry or immunoblot, 11 also showed overexpression. Two lymphomas morphologically indistinguishable from MCL but with an aberrant immunophenotype (CD5 negative, CD10 positive) both lacked overexpression of cyclin D1. These results underscore the significance of overexpression of the cyclin D1 protein as a specific marker for MCL. Detection of cyclin D1 overexpression on formalin-fixed, paraffin- embedded tissues using the DCS-6 monoclonal antibody can be applied for routine diagnostic purposes.     

Ethmoid sinus disease: CT evaluation in 400 cases. Part II. Postoperative findings

Clinical, pathologic, and computed tomographic (CT) findings were reviewed in 400 patients with ethmoid sinus disease, including 272 who had undergone surgery. The postoperative appearance of ethmoid sinuses on CT scans is a highly neglected subject in radiologic literature. The unique ethmoid anatomy permits a variety of surgical approaches, and radiologists must be familiar with the postoperative appearances if they are to recognize the effects of prior surgery and detect, when possible, the recurrence of disease. It is often difficult to evaluate the clinical significance of soft-tissue disease, despite good clinical correlation.     

Selection bias: neighbourhood controls and controls selected from those presenting to a Health Unit in a case control study of efficacy of BCG revaccination

Background  

In most case control studies the hardest decision is the choice of the control group, as in the ideal control group the proportion exposed is the same as in the population that produced the cases.