The Role of Platelet-Derived Growth Factor in the Pathogenesis of Sinonasal Polyps: Immunohistochemical Assessment in Epithelial, Subepithelial and Deep Layers of the Mucosa

OBJECTIVES: The aim of this study is to investigate the role of platelet-derived growth factor (PDGF) in the pathogenesis of sinonasal polyps. METHODS: Study group (groups 1-3) consisted of nasal polyp samples of patients with sinonasal polyps and the control group consisted of inferior turbinate samples of patients without nasal polyp. In group 1, 14 specimens from ethmoid sinus; in group 2, 10 specimens from nasal cavity; in group 3, 10 specimens from maxillary sinus; and in group 4 (control), 9 specimens from inferior turbinate were included. By immunohistochemical staining technique, the PDGF positivity index (PI) in mucosal layers and in the inflammatory cells were assessed at the epithelium (EP), subepithelial layer of lamina propria (SE), and deep paraglandular layer of the mucosa (D). RESULTS: Polymorphonuclear cell (PMNC)-percentage (%) values of ethmoid and maxillary sinus, and the PDGF PI from all cells of ethmoid sinus and nasal cavity were significantly higher than those of the control group. As mononuclear cell-% (MNC-%) increased, the PDGF_EP_basal PI, PDGF_SE_endothelial PI, and PDGF_D_endothelial PI decreased. As PMNC-PDGF PI increased, the PDGF_D_perivascular PI decreased and PDGF_D_endothelial PI increased. As PDGF-MNC PI increased, the PDGF_EP_apical PI, PDGF_SE_endothelial PI, and PDGF_D_endothelial PI decreased. As PDGF-all cells (PMNCs, MNCs, and fibroblasts) PI increased, the PDGF_EP_basal PI and PDGF_D_endothelial PI decreased, and the PDGF_D_perivascular PI increased. CONCLUSION: We concluded that the PDGF systems play important roles in polyp pathogenesis. Fibroblast-derived PDGF may be more important than MNC-derived PDGF in polyp developing process. Increased perivascular-PDGF-PI in deep layers of the mucosa may result in sinonasal polyp formation by causing an increase in vascular permeability and extracellular edema, and thus promoting migration of inflammatory cells to extracellular area. Tissue oxygenization may be important for the initiation of PDGF release system. Because of this reason, nasal obstruction should be medically treated earlier, and, if necessary, by surgical approaches.

An Outbreak of Tularemia in Western Black Sea Region of Turkey

The aim of this study was to investigate the source and the size of a tularemia outbreak in a village located in a non-endemic area. Five patients from the same village were admitted to hospital with the same complaints all within one week of September 2001. Tularemia was suspected and a diagnosis was made after physical and anamnesis examinations. The village was visited the same week that the patients were admitted to the hospital, in the January and April 2002. The villagers were examined and screened serologically by microagglutination method and the water sources were investigated bacteriologically. A total of 14 people were found to be infected from the outbreak and the oropharyngeal form was the only clinical presentation. Antibody titers ranged between 1 : 80 and 1 : 640. The patients responded well to the aminoglycoside plus tetracycline therapy. Examination of the pipewater and three springs revealed that all the water sources were contaminated by coliforms, however, Francisella tularensis could not be isolated in glucose-cystine medium. Antibody levels stayed stable or decreased seven months after. Tularemia had not been reported in this area before, so the first patients were misdiagnosed. In conclusion tularemia should be considered in differential diagnosis of patients with fever, sore throat and cervical lymphadenopaties.