Ultrasonography, CT and MRI of retropharyngeal ganglioneuroma: a very rare neoplasm in adults

Ganglioneuroma, a rare benign tumour, very occasionally presents in adult life. We report a case with the additional unusual feature of a retropharyngeal location.     

Localization of atrial natriuretic peptide receptors in the rat tongue and hard palate

The effect of a naturally occurring plant phenolic constituent (the acylphloroglucinol derivative, jensenone, derived from Eucalyptus jensenii) on the food intake of two folivorous marsupials, the common ringtail (Pseudocheirus peregrinus) and the common brushtail possum (Trichosurus vulpecula) was studied. When fed diets containing varying concentrations of jensenone, both species regulated their intake of jensenone so as not to exceed a ceiling intake. This ceiling was about twice as high for common ringtails as for common brushtails from northern Australia. Southern populations of common ringtails showed greatly reduced capacities to tolerate jensenone. When common brushtails were injected (0.5 mg.kg-0.75 body mass) with ondansetron (a selective antagonist of serotonin 5HT3 receptors), they ate significantly more jensenone than animals injected with physiological saline. The same pattern was observed when common ringtails were fed diets containing both jensenone and ondansetron (0.0035 mg.g-1 wet mass of diet). Ondansetron injection had no effect on food intake when the food did not contain jensenone while the addition of higher doses of ondansetron to diets of common ringtails very slightly reduced food intakes of a non-jensenone diet. When common brushtails were given 50 mg of jensenone by gastric lavage, their average subsequent intake of dietary jensenone matched the difference between the daily threshold and the dose given, although the response of individuals was highly variable. Lavage with water alone had no effect on subsequent jensenone intake compared with the pre-dose period. We interpret these results as evidence that the antifeedant effects of jensenone and related compounds are partly mediated by serotonin action on 5HT3 receptors most likely via "nausea" to condition a food aversion.     

Sleep-induced breathing instability. University of Wisconsin-Madison Sleep and respiration Research Group

We present a view of the neuromechanical regulation of breathing and causes of breathing instability during sleep. First, we would expect transient increases in upper airway resistance to be a major cause of transient hypopnea. This occurs in sleep because a hypotonic upper airway is more susceptible to narrowing and because the immediate excitatory increase in respiratory motor output in response to increased loads is absent in non-REM sleep. Secondly, sleep predisposes to an increased occurrence of ventilatory "overshoots", in part because abruptly changing sleep states cause transient changes in upper airway resistance and in the gain of the respiratory controller. Following these ventilatory overshoots, breathing stability will be maintained if excitatory short-term potentiation is the prevailing influence. On the other hand, apnea and hypopnea will occur if inhibitory mechanisms dominate following the ventilatory overshoot. These inhibitory mechanisms include: a) hypocapnia-if transient, will inhibit carotid chemoreceptors and cause hypopnea, but if prolonged will inhibit medullary chemoreceptors and cause apnea; b) a persistent inhibitory effect from lung stretch; c) baroreceptor stimulation, from a transient rise in systemic blood pressure immediately following termination of apnea or hypopnea may partially suppress the accompanying hyperpnea; d) depression of central respiratory motor output via prolonged brain hypoxia. Once apneas are initiated, reinitiation of inspiration is delayed even though excitatory stimuli have risen well above their apneic thresholds, and these prolonged apneas are commonly accompanied by tonic EMG activation of expiratory muscles of the chest wall and upper airway.     

Category Learning in Rhesus Monkeys: A Study of the Shepard, Hovland, and Jenkins (1961) Tasks.

In influential research, R. N. Shepard, C. I. Hovland, and H. M. Jenkins (1961) surveyed humans' categorization abilities using tasks based in rules, exclusive-or (XOR) relations, and exemplar memorization. Humans' performance was poorly predicted by cue-conditioning or stimulus-generalization theories, causing Shepard et al. to describe it in terms of hypothesis selection and rule application that were possibly supported by verbal mediation. The authors of the current article surveyed monkeys' categorization abilities similarly. Monkeys, like humans, found category tasks with a single relevant dimension the easiest and perceptually chaotic tasks requiring exemplar memorization the most difficult. Monkeys, unlike humans, found tasks based in XOR relations very difficult. The authors discuss the character and basis of the species difference in categorization and consider whether monkeys are the generalization-based cognitive system that humans are not. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Materials study of silicon-on-lnsulator material by TEM

Silicon-on-insulator (SOI) technology addresses the need for many different device applications, such as radiation tolerant devices, high voltage, and three-dimensional circuitry applications. Isolated silicon epitaxy (ISE) is a commercialised process which results in excellent SOI material quality with proven results, having overcome most of the obstacles of other processes, although only having reduced, not eliminated, threading dislocations. The remaining isolated dislocations have been examined in detail by transmission electron microscopy (TEM). These have been diagnosed as normal lattice dislocations, with no faults or twins in the material. The nature, source, and behavior of the remaining dislocations is discussed.     

Defect formation in epitaxial crystal growth

Factors affecting the nucleation and propagation of dislocations, stacking faults, microtwins, and inversion domain boundaries in epitaxially grown semiconductor layers are reviewed, with examples for heteroepitaxial MBE-grown layers on substrates having varying degrees of mismatch or different crystal symmetry. Mechanisms for generation of defects at the heterointerface and in the epilayer are discussed. For epilayers with bulk mismatch from 0 to 4%, methods for reducing defect density in the epitaxial layer are considered. Examples of structural details in the epilayers and at heterointerfaces, particularly those which may be revealed by transmission electron microscopy, are given.     

Digital low-pass filtering

Random noise beyond the maximum signal frequency of the imaging system can be removed by low-pass filtering without compromising signal transmission.     

Sturcture and function of the mononuclear phagocytic system (MPS) in chronic rhinosinusitis. A light and electron microscopic investigation (author's transl)

Neither the concept of the Reticulo-Endothelial-System (RES) Aschoff's (1924) nor that of the Reticulo-Histiocyte-System (RHS) provides a satisfactory framework into which the present knowledge of the phagocytic mononuclear cells can be fitted. Current knowledge concerning morphology, histochemistry (peroxydase and esterase activity), immunology (specific surface antigens, receptors on the cell membranes), function (immune phagocytosis, pinocytosis), kinetics (3H-thymidine labelling) and culture makes it possible to place all highly phagocytic mononuclear cells and their precursors in one system, which is called the Mononuclear-Phagocytic-System (MPS) (Langevoort, Cohn, Hirsch, Humphrey, Spector, van Furth, 1969). Kinetic studies with labelled cells have shown, that mononuclear phagocytes originate from precursor cells in the bone marrow (stem cell leads to monoblasts leads to promonocytes), than are circulating in the peripheral blood as monocytes and are transformed to tissue macrophages entering tissues. The MPS comprises following cells in following organs: connective tissue (histiocytes resp. macrophages); liver (Kupffer-cells); lung (alveolar macrophages); lymph nodes (free and fixed macrophages); bone marrow (macrophages); serous cavities (pleural and peritoneal macrophages); bone tissue (osteoclasts?); nervous system (microglial cells) (SEE Table 1). The reticular cells, endothelial cells and fibroblasts (fibrocytes) can therefore not be included in the MPS. Besides differences in morphology, histochemistry and function, they derive from mesenchymal cells and not from the bone marrow as the MPS. The present investigation demonstrates the structure and significance of the MPS in various kinds of chronic-specific and non-specific rhinosinusitis. On semithin sections two kinds of macrophages can be distinguished light-microscopically: 1. Larger macrophages with many phagosomes (storage cells) (Fig. 1A), which can exhibit sometimes a ring-shape on sections embracing greater parts of the interstitium (Fig. 1B). Such forms are mainly found in chronic (maxillary) sinusitis and are interpretated as "scavenger" macrophages. 2. The second type consists of smaller macrophages with extremely ruffling of the cell surface, which is interpretated as an expression of highly (specific?) stimulated states. These later macrophages can be seen mainly in edematous nasal polyps, which might be caused by allergic reactions of the anaphylactic type. The fine structure of the phagocytes is to some extent dependent on the actual development and functional state: there are "immature" macrophages, which are practically indistinguishable from blood monocytes (Fig. 2A); some of them can be stimulated and can therefore show many surface foldings and projections (Fig. 2B). The "mature" macrophage shows a well developed Golgi-area and many secondary lysosomes (Fig. 3). The storage type of the macrophages, which can predominate in some cases of chronic maxillary sinusitis, is characterized by many electron-lucent vacuoles (Fig. 4)...