Histopathological differences in bony destruction of malleus and incus following mastoidectomy.

OBJECTIVES: Upon direct inspection of surgically removed ossicles from the ears of patients with long-term post-mastoidectomy cavity problems, the extent of malleus destruction often appears greater in patients with a longer duration of cavity problems, whereas the extent of incus destruction does not appear to correlate with the duration of cavity problems. This study aimed to investigate this impression. MATERIALS AND METHODS: As a result of total middle-ear reconstruction, 41 ossicles (21 malleus and 20 incus bones) were obtained from 31 patients with post-mastoidectomy cavity problems. The ossicles were examined histopathologically, and the proportion of lamellar bone area to total bone area (expressed as percentage lamellar bone) was measured. We also calculated the inter-operation time, i.e. the time period between the previous mastoidectomy and the recent total middle-ear reconstruction; this parameter was used as an approximate measure of the duration of the patient's cavity problem. Correlations between percentage lamellar bone and inter-operation time were calculated for the two ossicles. RESULTS: The range of inter-operation times was seven to 65 years. We observed a correlation between percentage lamellar bone and inter-operation time for malleus bones (r = -0.512, p < 0.05), but not for incus bones. CONCLUSION: These results were in agreement with our pre-study impressions.

Evaluation of the role of human retinal vascular endothelial cells in the pathogenesis of CMV retinitis.

Previous studies of cytomegalovirus (CMV) retinitis have failed to definitively explain the exact mechanism by which CMV gains access to and initiates infection in the retina. Proposed theories have included leakage of the virus through vessels with altered permeability, with subsequent infection of surrounding glial cells. In an attempt to shed further light on this subject, a histopathologic examination of 30 autopsy eyes from patients with known systemic CMV disease was carried out using light microscopy, immunohistochemical and immunofluorescent techniques, and in-situ hybridization. Dual-staining methods were used to identify the exact cell type showing the presence of CMV antigens, namely vascular endothelial cells, glial cells, neuronal cells, and/or leukocytes. In those eyes with CMV retinitis, the sites of full-thickness retinal necrosis revealed viral presence mostly within Müller cells and perivascular glial cells, with focal areas of positive staining within retinal pigment epithelial cells (RPE) and neuronal cells. The retinal capillaries were devoid of endothelial cells in these areas. Adjacent to regions of full-thickness necrosis, some vessels showed the presence of a viral antigen within the endothelial cells. These findings suggest that retinal vascular endothelial cells can be infected with CMV. It can further be hypothesized that infection of vascular endothelial cells leads to infection of the surrounding glial and neuronal cells, with eventual spread to the RPE. Endothelial cells might not be present in areas of full-thickness necrosis due to mechanical forces from adjacent blood flow resulting in the sloughing of these cells.

Induction of KGF, basic FGF, and TGFalpha mRNA expression during healing of experimental TM perforations.

KGF (KGF), synthesized and secreted exclusively by stromal cells in epithelialized organs, specifically promotes proliferation of cells of epithelial origin, including keratinocytes. A related peptide, basic fibroblast growth factor (bFGF), has mitogenic properties for fibroblasts and endothelial cells. KGF expression is stimulated markedly in the skin during wound healing. To investigate the physiologic action of KGF in the healing of TM (TM) perforations, we examined KGF and KGF receptor (KGFR) mRNA transcript levels as well as those of bFGF and transforming growth factor-alpha (TGFalpha) in normal and wounded rat TM at varying intervals, using a semiquantitative reverse transcription-polymerase chain reaction (RT-PCR). We found KGF and TGFalpha mRNA expression to be induced rapidly, peaking 3 days after wounding and then declining. Expression of bFGF was induced gradually and remained increased until 7 days. In contrast, we found KGFR to be expressed in normal TM, remaining unchanged during TM repair. These results indicate that KGF and TGFalpha may mediate migration and proliferation of epithelial cells of the outer layer in the early stage of TM repair while bFGF may mediate the connective tissue reaction in the middle layer in a subsequent stage.