Effects of chronic administration of kanamycin on conditioned suppression to auditory stimulus in rats.
The conditioned suppression technique was employed to study the ototoxic effects of chronic administration of the antibiotic, kanamycin. Lever pressing behavior for food reinforcement of rats was suppressed in the presence of an auditory stimulus (sound) or visual stimulus (light) that had been previously paired with electric shocks. Repeated administration of kanamycin at the dose of 400 mg/kg/day for more than 50 days significantly attenuated the conditioned suppression to auditory stimulus but did not attenuate the conditioned suppression to visual stimulus. This finding suggests that the attenuating effect of chronic administration of kanamycin on conditioned suppression to auditory stimulus can be interpreted in terms of the selective action of the drug on the auditory system. (+info)
Outer membrane protein profiles of paired nasopharyngeal and middle ear isolates of nontypable Haemophilus influenzae from Mexican children with acute otitis media.
We studied nontypable Haemophilus influenzae (NTHi) isolates from simultaneous cultures of nasopharyngeal exudates (NEs) and middle ear fluids (MEFs) obtained by tympanocentesis from 57 children with acute otitis media (AOM). Preparations of outer membrane proteins (OMPs) from 14 pairs of NTHi strains recovered from NEs and MEFs from 10 children with unilateral AOM and four with bilateral AOM were subjected to sodium dodecyl sulfate polyacrylamide gel electrophoresis. The NTHi subtypes were determined by comparing the OMP profiles of the isolated strains with those of eight reference NTHi subtypes. Of the 14 pairs, 10 (71%) were identical, and one (8%) was different; three strains isolated from NEs (21%) did not correspond to any of the reference subtypes (nonsubtypable). Subtypes 4, 6, 5, 3, and 8 were isolated in the present study, thereby showing that their distribution is similar to that of subtypes isolated from children with AOM in the United States and suggesting that common otogenic strains are widely distributed in North America. (+info)
A persistent pharyngohyostapedial artery: embryologic implications.
A 3-year-old child was examined because of otorrhagia. CT scans showed an unusual vessel, confirmed by angiography, related to a persistent pharyngohyostapedial artery. This embryonic persistent artery associated with the normal internal carotid artery would explain the "duplication" aspect of the internal carotid artery. (+info)
Intranasally inoculated Mycoplasma hyorhinis causes eustachitis in pigs.
Specific-pathogen-free pigs were experimentally inoculated with Mycoplasma hyorhinis, Pasteurella multocida, or both bacterial isolates to evaluate the role of these bacteria in the pathogenesis of otitis media. Six pigs were inoculated intranasally with 4.4 X 10(8) colony-forming units (CFU) of M. hyorhinis. Twenty-one days later, three of these six pigs were inoculated intranasally with 5.0 X 10(8) CFU of P. multocida. Three additional pigs were also inoculated intranasally at the time with P. multocida alone. Two pigs served as uninoculated controls. Seven days later, all pigs were euthanatized. Histologically, subacute inflammation was found in 10 auditory tubes of six pigs and two tympanic cavities of two pigs inoculated with M. hyorhinis. Immunohistochemically, M. hyorhinis antigens were detected on the luminal surface of eight of 10 inflamed auditory tubes, and ultrastructural examination confirmed mycoplasmal organisms in two pigs. M. hyorhinis was isolated from the inflamed tympanic cavities of two pigs. None of the pigs inoculated only with P. multocida had otitis, and P. multocida was not isolated from the tympanic cavity. These findings indicate that M. hyorhinis can cause eustachitis but rarely otitis media in specific-pathogen-free pigs. (+info)
Pneumococcus activation of the 5-lipoxygenase pathway and production of glycoproteins in the middle ear of rats.
Pneumococcal otitis media is associated with the production of potent inflammatory mediators (leukotrienes), but the mechanism by which pneumococcus induces production of leukotrienes in the middle ear is poorly understood. In this study, up-regulation of 2 genes that govern the lipoxygenase pathway, cPLA2 and 5-LOX, was observed in rats following inoculation of pneumococcus into the middle ear cavity. Expression of cPLA2 was low, and 5-LOX gene expression was not detected in control animals. Up-regulation of cPLA2 and 5-LOX in middle ear epithelial cells was accompanied by an increase of high-molecular-weight glycoproteins in middle ear fluid and cells. These findings suggest that pneumococcus activates the lipoxygenase pathway by up-regulating expression of the cPLA2 and 5-LOX genes. This, in turn, may stimulate synthesis and secretion of high-molecular-weight glycoproteins that facilitate production of fluid in the middle ear cleft. (+info)
Prophylactic antiemetic therapy with a combination of granisetron and dexamethasone in patients undergoing middle ear surgery.
We have compared the efficacy of granisetron in combination with dexamethasone with each drug alone in the prevention of postoperative nausea and vomiting (PONV) after middle ear surgery. In a randomized, double-blind study, 120 patients (85 females) received granisetron 3 mg, dexamethasone 8 mg or granisetron 3 mg with dexamethasone 8 mg i.v. (n = 40 in each group), immediately before induction of anaesthesia. A standardized general anaesthetic technique was used. A complete response, defined as no PONV and no need for another rescue antiemetic during the first 3 h after anaesthesia, was recorded in 83%, 50% and 98% of patients who had received granisetron, dexamethasone and granisetron-dexamethasone, respectively. The corresponding incidences during the next 21 h after anaesthesia were 80%, 55% and 98% (P < 0.05; overall Fisher's exact probability test). In summary, prophylactic use of combined granisetron and dexamethasone was more effective than each antiemetic alone for the prevention of PONV after middle ear surgery. (+info)
Complement activity in middle ear effusions.
Evidence for complement utilization in middle ear fluids (MEF) from patients with otitis media with effusion was sought. It was found that cleavage products of C3, C4 and Factor B could be demonstrated immunochemically in MEF, and that native C3 was present in much lower concentrations than other proteins, relative to their serum concentrations. Haemolytic assays for C1-C5 showed that early complement components are inactivated in MEF. Potential mechanisms for complement utilization in MEF are discussed. (+info)
The distribution of the chorda tympani in the middle ear area in man and two other primates.
A serial section study of the distribution of the chorda tympani in the middle ear area was carried out in man, baboon and monkey. The tissues innervated by the chorda tympani could be related to a branchiomeric pattern. The early branches distributed post-trematic facial nerve fibres to hyoid arch tissues, where they were joined by elements from glossopharyngeal and vagus nerves. The rest of the distribution was to structures derived from mandibular arch tissue where branches of the auriculotemporal nerve were also present. Contributions to perivascular plexuses were noted as well as a connexion with the otic ganglion. (+info)