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This study was designed to investigate morphological changes in the tympanic membrane (TM) associated with cholesteatoma formation in experimental animals following application of propylene glycol to the middle ear. A 50% solution of propylene glycol was applied bilaterally to the middle ear cavities of 30 young-adult chinchillas. The animals were sacrificed for light and electron microscopic study at intervals of 2 days to 6 weeks after a single application of 0.2 ml of the propylene glycol solution. At 2 days there was complete destruction of the epidermal and mucosal layers of the TM. The denuded lateral surface rapidly became re-epithelialized by hyperplastic epidermal cells and by 2-3 weeks, keratinizing epidermis penetrated damaged areas of the fibrous layer of the lamina propria to reach the medial surface of the TM. These epidermal cells proliferated in the middle ear cavity, forming cholesteatomas. Our observations indicate that invasion of the intact, but structurally altered, tympanic membrane by hyperplastic epidermis is a primary mechanism of cholesteatoma formation in the animal model.

There is great interest in the structure of adiponectin as its oligomeric state may specify its biological activities. It occurs as a trimer, a hexamer and a high molecular weight complex. Epidemiological data indicate that the high molecular weight form is significant with low serum levels in type 2 diabetics but to date, has not been well-defined. To resolve this issue, characterization of this oligomer from bovine serum and 3T3-L1 adipocytes by sedimentation equilibrium centrifugation and gel electrophoresis respectively, was carried out, revealing that it is octadecameric. Further studies by dynamic light scattering and electron microscopy established that bovine and possibly mouse high molecular weight adiponectin is C1q-like in structure.

• Experimental studies have shown that if antibiotic otic drops reach the middle ear cavity they produce severe inflammation. However, the effects of these preparations on the tympanic membrane have not been thoroughly investigated. This study was designed to assess morphological changes in the chinchilla tympanic membrane two to 21 days after a single 0.2-mL application of an antibiotic otic preparation (Cortisporin Otic Suspension) to the middle ear cavity. At two days, the epidermal and the mucosal layers were destroyed. By four days, reepithelialization had occurred and all layers of the tympanic membrane subsequently became markedly hyperplastic. Disruption of the fibrous layer, invasion of keratinizing epidermis to the medial surface, and perforation were observed at three weeks. These findings indicate that tympanic membrane damage is a potentially significant aspect of the ototoxic properties of topical otic preparations. (Arch Otolaryngol Head Neck Surg1988;114:1007-1011)

This study was designed to investigate the cellular distribution and ultrastructure of melanin pigment in the stria vascularis and spiral ligament of the chinchilla cochlea. Typical dendritic melanocytes containing homogeneously distributed eumelanin granules were observed in the spiral ligament. In the stria vascularis melanin was found to occur in three types of cells (heavily pigmented cells that appear to be melanocytes, intermediate cells and basal cells). The melanocyte-like cells contain pigment globules composed of melanin granules, granular matrix and occasional lipid droplets in a configuration similar to that of neuromelanin. These cells are morphologically distinct from intermediate cells which contain sparsely distributed, small, dense granules apparently composed of melanin. The intermediate cells show a positive DOPA reaction and portions of the intermediate cell GERL system display intense acid phosphatase reactivity. The basal cells of the chinchilla stria were also found to contain occasional clusters of melanin granules. It is hypothesized that the basal cells may acquire melanin by donation from the other pigmented cells of the lateral cochlear wall.

Glycerol and urea are used as test agents in confirming the diagnosis of endolymphatic hydrops. Although both substances act as osmotic diuretics, recent evidence suggests that they may have differing physiologic effects on the inner ear. This study was designed to compare the morphologic effects of urea and glycerol on cochlear tissues, using the chinchilla as an experimental model. Animals were given subcutaneous injections of glycerol (2 g/kg) or urea (1.2 g/kg) over periods of 3 hours, 4 days, or 1 week. Both agents were found to produce ultrastructural changes, including spiral ligament vacuolization, intracellular alterations of the stria vascularis, and increased numbers of Hensen's bodies in outer hair cells. These alterations appeared indicative of metabolic stress, but not toxicity. The morphologic findings provided no evidence that glycerol and urea affect the inner ear by fundamentally different mechanisms of action.

The posterior-superior portion of the membranous wall of the chinchilla saccule is lined by pigmented epithelial cells which contain golden brown granules having three components (lipid droplets, granular matrix, and dense globules). Histochemical and electronmicroscopic studies indicate that the dense component is a form of melanin. The pigmented cells show morphological features suggestive of fluid transport function; they are also involved in decalcification and phagocytosis of otoconial crystals. These findings provide evidence that the saccular wall epithelium plays an active role in regulating endolymph composition and in clearance of debris from the endolymphatic space.

An automatic cloud tracking system based on the computation of the cross-covariance between satellite images has been developed. The six steps of the System for Automatic Wind Extraction from Geostationary Satellite-Data SAWEGS are preprocessing, cloud tracking, height assignment, earth location, wind vector computation, and quality control. The system embodies various unique aspects developed to address the problems encountered with an automated technique in general and this technique in particular. These aspects include histogram-based temperature slicing, cloud edge and surface enhancement, tracking trackability tests, and use of numerical analysis temperature profiles for height assignment. Examples of applying SAWEGS to visible data, to infrared data, and to a difficult tropical cyclone case show the good quality and coverage of resulting vectors as well as the remaining difficulties. PE 62759N PN 9F5255179 NEPRF WU 6.2-12

Symbiosis is an association between different organisms that leads to a reciprocal enhancement of their ability to survive. Similar mutually beneficial relationships can operate at the molecular level in the form of a hypercycle, a collective of two or more self-replicating species interlinked through a cyclic catalytic network. The superposition of cross-catalysis onto autocatalytic replication integrates the members of the hypercycle into a single system that reproduces through a second-order (or higher) form of nonlinear autocatalysis. The hypercycle population as a whole is therefore able to compete more efficiently for existing resources than any one member on its own. In addition, the effects of beneficial mutations of any one member are spread over the entire population. The formation of hypercycles has been suggested as an important step in the transition from inanimate to living chemistry, and a large number of hypercycles are expected to be embedded within the complex networks of living systems. But only one naturally occurring hypercycle has been well documented, while two autocatalytic chemical systems may contain vestiges of hypercyclic organization. Here we report a chemical system that constitutes a clear example of a minimal hypercyclic network, in which two otherwise competitive self-replicating peptides symbiotically catalyse each others' production.