An epidemiological investigation of 120 canine otitis externa cases in 1,370 dogs was done on the incidence rate, ear pinna shapes, breeds and their relationships. Eighty-five cases (12.6%) in 672 dogs with pendulous ears and 35 cases (5.0%) in 698 dogs with erect ears had otitis externa, and the difference between them was significant (P<0.05). Ninety-five auditory cerumen specimens were cultured for Malassezia pachydermatis (M. pachydermatis) and analyzed for concentrations of major fatty acids. Although rates of cases positive for M. pachydermatis in both ear pinna shapes were almost the same, i.e. 55.2% in the pendulous group and 53.6% in the erect group, the average total fatty acid level of the pendulous ear group was significantly (P<0.05) higher than that in the erect ear group after dismissing extraordinary levels in the Siberian husky. Isolated M. pachydermatis strains were examined for the effects of fatty acid supplementation on their growth. The majority of the strains utilized fatty acids and grew faster in fatty acid supplemented broth. These results suggest that M. pachydermatis, the predominant causative agent of canine otitis externa, prefers the auditory canal of dogs with lipid-rich earwax and grows fast, but growth strongly depends upon the canine breed.

This paper describes our modification of the classical gold chloride technique for the demonstration of the perisinusoidal stellate cells in the liver. The results of the method as introduced by von Kupffer (1876) are unpredictable. Using our modification, high quality gold preparations can be obtained. The method allows selective staining of retinol (vitamin A)-storing stellate cells in the liver and extrahepatic organs of various vertebrates. The sensitivity of the reaction is comparable to that of the fluorescence method for retinol. The technique is simple and the preparations keep for several years. Formol fixed specimens can be counterstained with Sudan III or hematoxylin. We have also developed a simple technique for making "sinusoid-net preparations," removing the parenchymal cells by supersonication. The clear visualization of the stellate cells that results has made it possible to study the distribution of these cells.

ABSTRACT. To investigate the predominance of Malassezia pachydermatis (M. pachydermatis) as a causative agent of canine otitis externa, ear cerumen samples were observed for adhesion of M. pachydermatis to the cornified epithelial cells by light and electron microscopes. The yeasts appeared not to adhere to the cornified epithelial cells directly, but they seemed to exist in the proximity of the epithelial cells with an electron opaque halo-like space around them. Polysaccharide and lipid staining techniques were conducted to identify the substances existing in that space. Lipid substances, not saccharides, were observed around the yeasts and the cornified epithelial cells. These results suggested that in the canine ear canal malassezia yeast attachment to the cornified epithelial cells is mediated by lipids. KEY WORDS: canine, Malassezia pachydermatis, otitis externa.J. Vet. Med. Sci. 63(6): 667-669, 2001 In Japan, the relative incidence of canine otitis externa was 4.4% of all canine diseases in 1993, but in 1997 it had increased to 8.1%, its highest recorded incidence rat [5]. Malassezia pachydermatis (M. pachydermatis) has been isolated from the cerumen samples of otitis externa-affected dogs and is involved as a causative agent [2,8]. M. pachydermatis is the most common organism found in ear specimens even in healthy dogs, accordingly this organism has been recognized as an opportunistic pathogen [3]. However, it remains to be investigated why M. pachydermatis selectively inhabits the ear canal of dogs and under what conditions it grows to cause otitis externa. Almost all microorganisms present host and site specificity and these depend upon microenvironmental factors such as host cell adhesion, nutrients for growth, growth inhibitors, pH and oxidation reduction potential [1]. M. pachydermatis yeasts associated closely with epithelial cells are commonly seen under the microscope in observation of cerumen smears from otitis externa (Fig. 1). If specific adherence of M. pachydermatis to epithelial cells is certified in survival and growth in the ear canal, new methods of treatment and prevention may be derived. Up to the present, however, published data showing evidence for yeast adherence to the cornified epithelial cells is not available. We therfore investigated the attachment of M. pachydermatis to the dermal epithelial cells of the ear canal by light and electron microscope observations of the ear cerumen specimens.In order to study the association between the yeasts and the cornified epithel cells, specimens for microscopy were taken from otitis externa cases with M. pachydermatis infections. Pieces of cerumen were fixed with paraformaldehyde and glutaraldehyde for 90 min at 4°C, then treated with 2% osmium tetroxide for 90 min at 0°C. Separately a treatment with potassium permanganate was used to identify the participation of saccharides in the possible adherence of M. pachydermatis to the cornified epithelial cells. After dehydration with ethyl alcohol the specimens were embedded in L. R. White res...

Effects of isoflurane on arterial blood pressure, regional blood flow in the brain stem, and renal sympathetic nerve activity were compared with those during vasodilator-induced hypotension using decerebrate unanesthetized cats. Either prostaglandin E₁ (PGE₁) or trinitroglycerin (TNG) was used to decrease the mean arterial pressure 30% below the control level. The effects of isoflurane (0.5 MAC for 15 min) were examined in the following three conditions: (1) during PGE₁-induced hypotension; (2) during TNG-induced hypotension, and (3) without either vasodilator. Isoflurane decreased the brain stem blood flow in parallel with a systemic blood pressure fall. Electrical activity of the renal sympathetic nerve consisted of a high-amplitude phasic and a low-amplitude tonic discharge. Isoflurane decreased the phasic activity and increased the tonic activity. Although the two vasodilators had a similar effect on systemic blood pressure and renal sympathetic discharge, TNG decreased the brain stem blood flow to a lesser extent than PGE₁. However, the effects of isoflurane on all parameters were statistically identical in the three conditions not treated and pretreated with either vasodilator. Also, the blood concentrations of isoflurane did not differ among the three conditions. The present study demonstrates that isoflurane produces similar effects on systemic blood pressure, regional cerebral blood flow and sympathetic efferent discharge during vasodilator-induced hypotension and without any vasodilator.

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