[Minimally invasive treatment of osteoid osteoma with CT-guided radiofrequency ablation in long-term follow-up]. / Die minimalinvasive Therapie beim Osteoidosteom mittels CT-gesteuerter Thermokoagulation im Langzeitverlauf.

AIM: We treated 74 patients with symptomatic osteoid osteoma by CT-guided radiofrequency ablation (CT-RF) and investigated the rate of success and complications. PATIENTS AND METHODS: 74 patients were treated by CT-RF between March 1997 and August 2001. The nidus was first located by thin-cut CT sections and then penetrated by a 2 mm coaxial drill or an 11-gauge Jamshidi needle followed by insertion of the RF probe and heat application for a period of 4-6 minutes at 90 degrees C. We investigated the recurrence of pain, complications, hospital stay, duration of postoperative pain and function. RESULTS: Nine recurrences occurred after the initial procedure, and one after a second CT-RF (rate of primary success 87.8 %, rate of secondary success 88.8 %; 98.6 % success rate in all). There was one minor complication in one case. CONCLUSIONS: CT-guided RF ablation cured 73 of 74 patients (98.6 %). It is a safe, simple, cost effective and minimally invasive treatment, which has stood the test of a long-term follow-up and we suggest it to be the treatment of choice in most cases.

Characterization of M cell formation and associated mononuclear cells during indomethacin-induced intestinal inflammation.

M cells represent an important gateway for the intestinal immune system by delivering luminal antigens through the follicle-associated epithelium to the underlying immune cells. The goal of this study was to characterize this route of antigen uptake during intestinal inflammation by characterizing M cell formation and M cell-associated lymphocytes after indomethacin challenge in rats. We demonstrated increased M cell formation as early as 12 h after a single injection of indomethacin. The elevated M cell counts were determined until day 3 and returned to basal levels after 7 days. Electron microscopic studies revealed an expansion of mononuclear cells inside the M cell pocket that were characterized predominantly as B cells, T cell receptor (TCR)alphabeta- and CD4-positive T cells, whereas other markers such as CD11b, CD8 and CD25 remained unchanged. In situ hybridization studies showed increased expression of interleukin (IL)-4 by lymphocytes during intestinal inflammation in the Peyer's patch follicle. These studies illuminate the relevance of M cells during intestinal inflammation and suggest that M cells derive from epithelial cells in a certain microenvironment.

Characterization of M cell development during indomethacin-induced ileitis in rats.

BACKGROUND: M cells play an important role in the intestinal immune system as they have a high capacity for transcytosis of a wide range of microorganisms and macromolecules. However, little is known about the role of M cells during intestinal inflammation. AIM: We studied M cell development during indomethacin-induced intestinal inflammation in rats. METHODS: Ileitis in rats was induced by two subcutaneous injections with indomethacin (7.5 mg/kg) given 24 h apart. Rats were sacrificed after 14 days and tissue was analysed by fluorescence microscopy and electron microscopy. M cells could be visualized by using the FITC-labelled mAb anti-cytokeratin (CK)-8 (clone 4.1.18), which was recently identified as specific M cell marker in rats. The number of cytokeratin-8 positive M cells was related to the surface of the follicle associated epithelium. For morphological studies, we used both transmission electron microscopy (T.E.M.) and scanning electron microscopy (S.E.M.). RESULTS: In non-inflamed ileum M cells were scarce. Only 4% of the follicle associated epithelium were M cells, whereas an increase of M cells up to 11% was found in inflamed follicle associated epithelium (P < 0.001). The rate of M cell induction depended on the macroscopic degree of inflammation. T.E.M./S.E.M. studies showed that in inflamed tissue most M cells underwent apoptosis with typical morphological signs. In contrast to apoptotic M cells, the neighbouring enterocytes usually appeared intact. The number of mononuclear cells below the follicle associated epithelium was significantly increased. S.E.M. studies revealed that during induced ileitis mononuclear cells migrated from the lamina propria into the gut lumen by passing through apoptotic M cells. CONCLUSIONS: During indomethacin-induced ileitis in rats the increase in M cell number in association with apoptosis of M cells may alter the intestinal barrier function. These observations may play a pivotal role in the pathogenesis of chronic intestinal inflammation, e.g. in inflammatory bowel disease.

Towards targeting strategies for oral immunization--identification of marker antigens in rat M cells.

Specialized M cells of the follicle-associated epithelium (FAE) of Peyer's patches in the gastrointestinal and respiratory tracts play a crucial role in the immune surveillance of mucosal surfaces and are essential for the induction of mucosal immune responses. These cells transport luminal antigens to the underlying germinal centers and thereby initiate an immune response or induce tolerance. Mucosal immune responses could be significantly enhanced if oral antigens could be directly targeted to the apical surface of M cells. However, thus far M cells have not been isolated and suitable surface markers have not been described. For the characterization and identification of potential molecular markers of M cells the follicle associated epithelium of Peyer's patches from the small intestine of rats was analyzed by indirect immunofluorescence and immunogold electronmicroscopy. The expression of intermediate filament proteins in the FAE was found to be heterogeneous. Immunoreactivity of a specific monoclonal cytokeratin 8 antibody (clone 4.1.18) was selectively found in cells which were additionally characterized by the lack of staining for alkaline phosphatase in their apical membranes. In the FAE this property is an accepted criterium for the presence of M cells. The antigen recognized by the clone 4.1.18 is expressed in substantially higher amounts in M cells of Peyer's patches as compared to neighbouring epithelial cells or "normal" enterocytes and thus can be employed as an intracellular molecular marker for M cells of Peyer's patches in rats. It is expected, that this marker will be very helpful for the isolation of M cells.

Immunocytochemical characterization of the follicle-associated epithelium of Peyer's patches: anti-cytokeratin 8 antibody (clone 4.1.18) as a molecular marker for rat M cells.

For the characterization and identification of potential molecular markers of M cells, the follicle-associated epithelium (FAE) of Peyer's patches from the small intestine of rats was analyzed by indirect immunofluorescence and immunogold electron microscopy. The expression of intermediate filament proteins in the FAE was found to be heterogeneous. Immunoreactivity of a specific monoclonal cytokeratin 8 antibody (clone 4.1.18) was selectively found in cells which were additionally characterized by the lack of staining for alkaline phosphatase in their apical membranes. In the FAE, this property is an accepted criterium for the presence of M cells. Further, these cells were found to be devoid of mucin and were thus distinct from goblet cells. The antigen recognized by the clone 4.1.18 is expressed in substantially higher amounts in M cells of Peyer's patches as compared to neighboring epithelial cells or "normal" enterocytes and thus can be employed as an intracellular molecular marker for M cells of Peyer's patches in rats.