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  • 1
    ISSN: 1432-0878
    Keywords: Enterochromaffin-like cells ; Ultrastructure ; Hypertrophy ; Hypergastrinaemia ; Gastrin infusion ; Omeprazole ; Rat (Sprague Dawley) ; Syrian hamster ; Guinea pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The present report describes the ultrastructure of the enterochromaffin-like (ECL) cells in the stomach of the rat, hamster and guinea pig, and the ultrastructural consequences of long-term hypergastrinaemia evoked either by continuous infusion of synthetic human (Leu15)-gastrin-17 for 4 weeks (rats) or by daily treatment with large doses of the antisecretory agent omeprazole for 2–10 weeks (rats, hamsters and guinea pigs). As a result, the ECL cells increased greatly in size (maximal effect after 2 weeks of omeprazole treatment, no further gain in size after 4 or 10 weeks). Also the endoplasmic reticulum and Golgi area were enlarged. The most conspicuous feature of the ECL cells is the cytoplasmic vesicles, which are of varying size and either devoid of a dense core or with a small, often eccentrically located dense core. The vesicles probably represent the main storage site of the secretory products of the ECL cell. In addition, the cytoplasm contains granules, which differ from the vesicles in that they possess a more or less electron-dense core, surrounded by a narrow halo. The size of the vesicles ranged from small to very large, while the granules were uniformly small. Many vesicles were seen to lie very close together, some displaying an irregular outline (vacuole-like vesicles), at times giving the impression that they were undergoing fusion. The profile size (median value) of the vesicles was unaffected by gastrin infusion for 4 weeks. However, there was a tendency to a relative increase in the number of very small vesicles. In contrast, the vesicles became larger during the omeprazole treatment. Also, the number of vesicles that seemed to be engaged in fusion increased after omeprazole treatment but not after gastrin infusion. The observations support the view that ECL cells are influenced by gastrin. The effects of gastrin infusion and of omeprazole treatment on ECL cell ultrastructure were not completely identical. It cannot be excluded that the omeprazole-evoked achlorhydria evokes effects unrelated to those of hypergastrinaemia on the ECL cells, or that endogenous gastrins may evoke effects that are in some ways distinct from those of synthetic human (Leu15)-gastrin-17. Alternatively, the additional effects seen after long-term omeprazole treatment may reflect simply the duration of the hypergastrinaemic stimulus.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 168 (1998), S. 619-623 
    ISSN: 1432-136X
    Keywords: Key words Endothelin ; Gill ; Oncorhynchus mykiss ; Osmoregulation ; Respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The lamellae of the fish gill are the primary sites for oxygen uptake from the water. Here, only two very thin layers of cells separate the blood from the water. Therefore, energetically costly ion-fluxes will also occur between blood and water, and it has been hypothesised that the blood flow within the lamellae can be regulated through vasoconstriction, but evidence for this has been lacking. Through direct observations of the lamellae of rainbow trout (Oncorhynchus mykiss) in vivo, using epi-illumination microscopy, we show here that an endothelium-derived vasoactive peptide, endothelin-1 (ET-1, 0.2 μg kg−1 or 1.0 μg kg−1), is able to completely constrict the vascular sheet in the lamellae, probably by inducing contraction of pillar cells. This coincided with a dose-dependent increase in ventral aortic blood pressure (rising from 6.6 kPa to 12.0 kPa in response to the high ET-1 dose). However, blood continued to flow through the marginal channel that circumvents each lamella. Thus, ET-1 caused an intralamellar blood shift from the lamellar sheet towards the marginal channels. Vasoconstriction in the lamellae is likely to provide the fish with a mechanism for matching its respiratory surface area with its respiratory needs, thereby minimising ion-fluxes.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Medical & biological engineering & computing 15 (1977), S. 209-218 
    ISSN: 1741-0444
    Keywords: Evaporation ; Hygrometry ; Insensible perspiration ; Transepidermal water loss ; Sweat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Description / Table of Contents: Sommaire Une nouvelle méthode pour mesurer les échanges hydriques à travers la peau a été mise au point. Cette méthode, fondée sur l'estimation du gradient de pression de la vapeur adjacente à la surface de la peau, permet d'exposer cette surface à l'air ambiant normal pendant toute la durée de la mesure. L'humidité et la température du microclimat entourant la peau sont ainsi minimisées. Sur la base de cette nouvelle méthode, un instrument pour mesurer de petites quantité d'eau s'evaporant d'une surface ou absorbées par elle, calculées par unités de temps et de surface, a été mis au point et sa précision est examinées. Cet instrument, qui est destiné à être utilisé dans une gamme de températures allant de 15 à 40°C. et pour des valeurs de la pression atmosphérique comprises entre 98 et 104 kPa, s'est révélé offrir une mesure de haute précision et une sensibilité améliorée par comparaison avec les systèmes prélablement employés. Il a tout d'abord servi aux recherchest portant sur le taux d'évaporation à la surface de la peau des nouveaux-nés, de malades présentant des troubles de la thyroide et de brûlés. La construction de l'instrument le rend néanmoins particulièrement bien adapté pour mesurer les taux d'évaporation dans de nombreux autres domaines d'application.
    Abstract: Zusammenfassung Es wurde eine neue Methode zur Messung des Wasseraustausches durch die mensch liche Haut entwickelt. Die auf der Schätzung des Dampfdruckgradienten in unmittelbarer Nachbarschaft der Hautoberfläche beruhende Methode gestattet es, die zu untersuchende Oberfläche der normalen Umgebungsluft während der gesamten Meßperiode auszusetzen. Dadurch wird ein minimaler Einfluß auf die Feuchtigkeit und Temperatur des die Haut umgebenden Mikroklimas erzielt. Auf der Grundlage des neuen Verfahrens wird ein Instrument zur Messung kleiner Mengen von Wasser beschrieben, das von einer Oberfläche pro Zeit- und Flächeneinheit absorbiert oder verdampft wird, und seine Genauigkeit wird besprochen. Das für Verwendung im Temperatur-bereich von 15–40°C und im Luftdruckbereich von 98–104 kPa bestimmte Gerätzeigte im Vergleich mit vorher verwendeten Geräten eine hohe Genauigkeit und verbesserte Empfindlichkeit. Es wurde vor allem fur die Untersuchung der Verdampfungsrate von der Hautoberfläche Neugeborener wie auch thyrotoxischer und Bunddwunden-Patienten verwendet. Der Bau des Instrumentes macht es aber auch für die Messung von Verdampfungsraten bei vielen anderen Anwendungen sehr gut geeignet.
    Notes: Abstract A new method for the measurement of the water exchange through the human skin has been developed. The method, based on the estimation of the vapour-pressure gradient immediately adjacent to the surface of the skin, permits the surface investigated to be exposed to normal ambient air during the entire period of measurement. A minimal influence on the humidity and the temperature of the microclimate surrounding the skin is thereby achieved. On the basis of the new method an instrument for measuring small amounts of water evaporated from or absorbed by a surface per unit time and area is described and its accuracy discussed. The instrument, which is intended for use in the temperature range 15–40°C and the atmospheric pressure range 98–104 kPa, has proved to offer a high accuracy and an improved sensitivity in comparison with devices previously employed. It has been used primarily for investigations of the rate of evaporation from the skin surface of newborn infants as well as of thyrotoxic and burned patients. The construction of the instrument, however, makes it well suited for the measurement of evaporation rates in many other fields of application.
    Type of Medium: Electronic Resource
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