A bacteriological and histological study of experimentally induced acute pneumococcal sinusitis was performed in 69 New Zealand White rabbits. The sinus ostium was blocked on one side on the first day of the experiment. On the second day, 10(7)-10(9) Streptococcus pneumoniae in 1 ml were injected into the same sinus cavity. Purulent sinusitis developed unilaterally in all rabbits. Histological examination of the sinus mucosa revealed edema, dilated venules, leukocytic infiltration of the mucosa as well as localized epithelial lesions. On staining with acridine orange at pH 4.0, the bacteria were observed in the secretion but not in the mucosa. When we used Streptococcus pneumoniae subjected to an animal passage, the bacteria were re-isolated in 9/10 infected sinuses. Neither sole occlusion of the ostium nor injection of pneumococci into a sinus cavity with a patent ostium resulted in a bacterial sinusitis. Obstruction of the sinus ostium and the use of a virulent Streptococcus pneumoniae strain were essential for the induction of sinusitis in rabbits.
The blood flow in the maxillary sinus mucosa was studied in 35 New Zealand White rabbits. The blood flow measurements were made by two methods, one with use of Rb86Cl and the other with 15 microns Sn113-labelled microspheres. With the Rb86Cl method the blood flow of the infected sinus mucosa was about 0.8 ml x min-1 x g-1 when correction was made for radioactivity in the secretion. The radioactivity found in the secretion probably reflects an increase both in vascular and mucosal permeability and in blood flow. When microspheres labelled with Sn113 were used, the mean mucosal blood flow in the presence of sinusitis was found to be 0.83 +/- 0.56 ml x min-1 x g-1. This blood flow was significantly higher than on the control side. In a control series, mere blocking of the ostium did not significantly alter the blood flow in the sinus mucosa.
In previous studies, sinus secretions have been analysed concerning pO2, pCO2 and pH. In this study the energy metabolism in the maxillary sinus mucosa and secretion was studied in 33 New Zealand White rabbits. In freeze-dried samples, glucose and lactate were analysed by enzymatic assays and ATP by HPLC. In the purulent sinusitis, lactate concentration in the mucosa was 5.67 mmol X kg-1 w.w. and significantly higher than in the control sinus. Also in the non-purulent sinusitis, lactate was increased in the mucosa. The lactate concentrations in the secretion were 9.8 and 8.4 mmol X kg-1 w.w. in purulent and non-purulent secretions respectively and are probably the result of a diffusion from the mucosal cells and of leukocyte metabolism. A reduced ATP content, with increases in ADP and AMP, in the sinus mucosa of the purulent sinusitis suggests a relative energy depletion which could result in impaired epithelial function.
An acute pneumococcal maxillary sinusitis was induced in New Zealand white rabbits by unilateral obstruction of the sinus ostium and then injecting 10(8) Streptococcus pneumoniae into the sinus. After subjecting this bacterial strain to one animal passage, the bacteria were reisolated in nine of ten infected maxillary sinuses. All rabbits developed a unilateral purulent sinusitis, while a non-purulent sinusitis could be induced by occlusion only of the maxillary ostium. By using a non-diffusable tracer, microspheres labelled with Sn113, blood flow measurements were performed on these sinuses. These studies showed that the blood flow of the infected sinuses was significantly higher than on the control side. However, in chronic sinusitis (with a blocked ostium), the blood flow did not differ significantly from that on the control side. Biochemical studies in the animals with purulent sinusitis demonstrated that lactate concentration in the mucosa was significantly higher as compared to the control side. The glucose concentration was significantly lower in the mucosa of the infected side, as was the ATP content of the sinus mucosa in purulent sinusitis. These results indicate an increased glycolysis as well as a relative energy depletion in the sinus mucosa in purulent sinusitis, which could result in an impaired epithelial function.
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