Lipopolysaccharide endotoxin (LPS) was extracted from Haemophilus influenzae type b by using Westphal's phenol water method. The ears of 40 adult male guinea pigs were subsequently inoculated with 10 micrograms/ml solutions of LPS by transmeatal injections. Groups of animals were then sacrificed from day 2 to day 24 after the injections to observe the pathological changes produced. Massive serous effusions filled the tympanic bullae on days 2 and 4, after which the amount of fluid present gradually decreased so that it could hardly be seen on day 11. Pathological changes found in the mucosa included marked interstitial edema, dilated capillaries, as well as elevated and thickened epithelium with intracellular edema. These findings gradually subsided by day 24. We believe that the major pathogenetic factors present were due to the transudation and injury of the middle ear epithelium disturbing mucociliary transport activity, with increased secretions participating somewhat in inducing the effusion. We further suggest that H. influenzae endotoxin may play an active role in the clinical development of otitis media with effusion.
Platelet-derived growth factor (PDGF) was localized in human middle ear cholesteatoma tissue by an immunoperoxidase technique using rabbit anti-human PDGF IgG. PDGF was found mainly in basal cells and in granulation tissue, and especially involved monocytes and fibroblast-like cells. The external ear canal epithelium was not significantly stained by anti-human PDGF. Findings demonstrate that the presence of PDGF in cholesteatoma is in response to inflammation and wound healing in the middle ear. PDGF in vitro was found to stimulate protein synthesis and cellular terminal differentiation of basal keratinocytes. PDGF also stimulated monocytes to form multinucleated osteoclast-like cells. These multinucleated cells, in turn, induced the resorption of devitalized bovine bone. This bone resorption was seen in co-cultures of osteoblasts and multinucleated osteoclast-like cells in the presence of PDGF, suggesting that cell-to-cell interaction plays a role in bone resorption. The present study suggests that PDGF takes part in the clinical development and the destructive effect of cholesteatoma.
A new electric data acquisition and operational control system was developed for time‐of‐flight sputtered neutral mass spectrometry (TOF‐SNMS). The system is designed for high‐speed data acquisition, data processing, and data streaming. The developed system is constructed on an NI‐PXI platform and provides timing clocks for the TOF‐SNMS operation. The system performs data processing of noise suppression and ion counting while acquiring TOF mass spectrum for 13‐microsecond length at sampling rate of 3 GS/s for every 1 millisecond. In addition, the system acquires and records TOF mass spectrum of 60‐microsecond length at sampling rate of 3 GS/s for every 1 millisecond without data processing. The system detects single ion signals from accumulated TOF mass spectrum of 107 times and counts up to 10 ions accurately from a single event of TOF mass spectrum.
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