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  • 1
    Electronic Resource
    Electronic Resource
    Experimental protoporphyria in hairless mice: An animal model for photodynamically induced dermatitis (1980)
    Springer
    Veterinary research communications 4 (1980), S. 183-194 
    Details
    ISSN: 1573-7446
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Kurzfassung Die Porphyrien sind Störungen in der Biosynthese des Haem, die durch Überproduktior Akkumulation und Ausscheidung exzessiver Mengen von Porphyrinen oder Porphyrinvorläufern charakterisiert sind. In vorliegender Arbeit wird eine kurze Übersicht gegeben über die Biosynthese der Porphyrine, ihre Verbreitung in der Natur und die verschiedenen Typen von erythropoietischen Porphyrien, die bei Tieren und Menschen gefunden worden sind. Besondere Aufmerksamkeit wird der photo-sensitierenden Aktivität der Porphyrine gewidmet. Obwohl eine Beziehung zwischen Porphyrinen und Photosensitivität bekannt ist, ist die Pathogenese der Photodermatitis bei Patienten mit photosensitiver Porphyrie noch nicht voll geklärt. Haarlose Mäuse wurden mit 3,5-di-Carbethoxy-1,4-dihydrocollidin gefüttert um sie protoporphyrisch zu machen. Mit diesen Tieren wurden Untersuchungen über den Schutzeffekt der Reinigun von aktiven Sauerstoffverbindungen bei Photohaemolyse und Überempfindlichkeit der Haut gegenüber violettem Licht durchgeführt. Es wird gefolgert, dass: 1. Neben reinem Sauerstoff könnten auch andere aktive Sauerstoffverbindungen wie Superoxid und Wasserstoffperoxid an der Photohämolyse beteiligt sein und möglicherweiseauch bei Reaktionen die zur Photodermatitis führen. 2. Protoporphyrische, haarlose Mäuse können als empfindliche Modelle für die Untersuchung der Pathogenese der photodynamisch-induzierten Dermatitistypen verwendet werden.
    Abstract: Resume Les porphyries sont des désordres de la biosynthèse de l'héme caractérisées par une surproduction, une accumulation et l'excrétion de taux élevés de porphyrines ou de leurs précurseurs. Cet article passe rapidement en revue la biosynthèse des porphyrines, leur distribution dans la nature et les différents types de porphyries rencontrés chez l'homme et l'animal. Une attention particulière est accordée à l'activité photosensibilisante des porphyrines. Malgré la relation démontrée entre les porphyrines et la photosensibilité, la pathogénie des lésions cutanées chez les malades atteints de photosensibilisation n'est pas totalement connue. Des souris à peau nue rendues protoporphyriques par ingestion de 3-5-dicarbethoxy-1,4-dihydrocollidine ont été utilisées pour étudier l'effet protecteur de l'oxygène contre la photohémolyse et l'hypersensibilité de la peau à la lumière ultraviolette. Les conclusions de ce travail sont les suivantes: 1. Malgré la protection obtenue par l'oxygène natif d'autres composés oxygènés peuvent être concernés par la photohémolyse et peut être dans les réactions conduisant à la photosensibilisation cutanée. 2. Les souris à peau nue protoporphyriques peuvent être utilisées comme modèle pour étudier la pathogénie des dermatites induites par la photosensibilisation.
    Notes: Abstract The porphyrias are disorders of the biosynthesis of haem which are characterized by an overproduction, accumulation and excretion of excessive amounts of porphyrins or porphyrinprecursors. This paper briefly reviews the biosynthesis of porphyrins, their distribution in nature and the various types of erythropoietic porphyrias that has been found in man and animals. Particular attention will be given to the photosensitizing activity of porphyrins. In spite of the recognized relationship between porphyrins and photosensitivity the pathogenesis of the photodermatitis of patients who suffer from photosensitive porphyria is not fully understood. Hairless mice which were made protoporphyric by feeding them 3,5-dicarbethoxy-1,4-dihydrocollidine were used to study the protective effect of scavengers of active oxygen species against photohaemolysis and hypersensitivity of the skin to violet light. It is concluded that: 1. besides singlet oxygen other active oxygen species such as superoxide and hydrogen peroxide might also be involved in photohaemolysis and possibly in the reactions leading to the photodermatitis. 2. protoporphyric hairless mice can be used as sensitive models to study the pathogenesis of photodynamically induced types of dermatitis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02278496
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  • 2
    Electronic Resource
    Electronic Resource
    Long-term persistence of DNA alkylation in hamster tissues afterN-nitrosobis(2-oxopropyl)amine (1990)
    Springer
    Journal of cancer research and clinical oncology 116 (1990), S. 149-155 
    Details
    ISSN: 1432-1335
    Keywords: Immunocytochemistry ; Alkylation ; Alkylguanines ; Hamster ; Nitrosamines ; Pancreas ; Liver ; Lung ; Kidney
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The persistence of 7- andO 6-alkylation of guanine in DNA of cell nuclei of male Syrian hamster pancreas, liver, kidneys, lungs [target tissues ofN-nitrosobis (2-oxopropyl)amine (BOP)] and salivary glands (nontarget tissue) was studied immunocytochemically 6 h, 1, 3, 7, 14, 28, and 56 days after a single s.c. injection of 20 mg BOP/kg. Conventional antisera raised againstO 6-methylguanine and imidazole-ring-opened 7-methylguanine were used. Persistent alkyl-specific staining was observed for up to 7 days (7-alkylguanine) or 56 days (O 6-alkylguanine) in inter- and intralobular duct cells and centro-acinar cells of the pancreas, periportal hepatocytes and bile duct cells of the liver, cells of the proximal convoluted tubules of the renal cortex, and bronchiolar Clara and alveolar cells in the lungs. Both adducts disappeared from centrilobular liver cells within 1 day, from pancreatic acinar cells within 3 days, and from ducts and acini of the submandibular salivary glands within 14 days after BOP treatment. A high level of persistentO 6-alkylation of guanine was related with a high tumor incidence only in case of the ductal/ductular system of the pancreas, the main target tissue of BOP-induced carcinogenesis. The relatively weak carcinogenicity of BOP in other tissues with long-term persistence ofO 6-alkylguanine in DNA indicates that the formation and persistence of DNA alkylation are not sufficient to account for the carcinogenic organotropism of BOP. Additional factors, such as cell proliferation, appropriate promoting stimuli and the (onco)genes critically involved, may be as important as the modification of DNA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01612669
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  • 3
    Electronic Resource
    Electronic Resource
    Enzyme-cytochemistry of the saccus dorsalis of the rainbow trout, Salmo gairdneri Richardson (1976)
    Springer
    Histochemistry and cell biology 48 (1976), S. 293-306 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the saccus dorsalis of the rainbow trout, Salmo gairdneri Richardson, the activity of various enzymes (transferase, lyases, oxidoreductases, hydrolases) have been studied in detail. The results of this enzyme-cytochemical study firmly demonstrate that the organ is metabolically highly active. The epithelial cells have a strong energy metabolism. Energy production can take place under aerobic as well as under anaerobic conditions. Evidence is presented that glucose from blood is directly utilized for energy demands. The epithelial cells show also high synthetic activities. The moderate amino acid metabolism may participate in the synthesis of an acid mucopolysaccharide-protein complex, especially in the so-called dark cells. Lipid metabolism appears to be restricted to the mitochondria, indicating a high turnover of lipid moieties in the membranes. In contrast to the normal looking mitochondria, the macromitochondria — besides shape and localization — have an extremely high lipid and monoamine metabolism, which may point to a special function in the cellular economy. The high activity of enzymes involved in the degradation of monoamines and in the hydration of CO2 is of particular physiological interest. The significance of the observations is discussed in relation to formerly obtained indications on the involvement of the saccus dorsalis in fluid secretion, extrusion of organic substances of low molecular weight into the ventricular system and uptake of organic substances from the cerebrospinal fluid. The hypothesis of the saccus dorsalis being an analogue of the choroid plexus is supported by several relevant data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00499246
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  • 4
    Electronic Resource
    Electronic Resource
    The influence of different nutrients on plasma cholecystokinin levels in the rat (1988)
    Springer
    Cellular and molecular life sciences 44 (1988), S. 21-23 
    Details
    ISSN: 1420-9071
    Keywords: Rats ; nutrients ; cholecystokinin ; pancreatic secretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Isocaloric and isovolemic amounts of protein (casein), fat (intralipid) and carbohydrate (saccharose) and an isovolemic control solution of water were administered intragastrically to conscious rats. The plasma CCK levels, determined by a sensitive and specific radioimmunoassay, showed an increment of 6.3±0.6, 2.7±0.5, 1.7±0.4 and −0.9±0.4 pM, respectively (basal value 2.5±0.3 pM). The threshold increment of plasma CCK to stimulate pancreatic enzyme secretion by exogenous CCK was found to be 1.5 pM. It is therefore concluded that casein is a potent stimulus for CCK secretion and pancreatic secretion, but that fat and even carbohydrate, although less potent, also produce a CCK increment above the threshold for pancreatic secretion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01960229
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  • 5
    Electronic Resource
    Electronic Resource
    Modulation of putative preneoplastic foci in exocrine pancreas of rats and hamsters (1989)
    Springer
    Digestive diseases and sciences 34 (1989), S. 789-796 
    Details
    ISSN: 1573-2568
    Keywords: pancreas ; carcinogenesis ; rat ; hamster ; fat ; coffee
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of coffee and dietary fat (alone and in combination) on the development of preneoplastic lesions in exocrine pancreas were investigated in rats and hamsters, treated with azaserine or N-nitrosobis(2-oxopropyl)amine, respectively. The animals were given the respective diets (5% or 25% corn oil) and coffee (instead of drinking water) within one week after the treatment with carcinogen. At four months postinitiation, the pancreata were quantitatively examined for the number and size of preneoplastic foci. In rats, coffee alone inhibited growth of acidophilic foci and, moreover, slightly inhibited the positive modulating effect of fat on growth of these foci, pointing to a negative rather than a positive interaction between these two life-style factors. In hamsters, coffee alone enhanced growth of cystic foci, whereas fat alone enhanced growth of ductular foci. An interaction between fat and coffee on pancreatic carcinogenesis in hamsters could not be demonstrated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01540355
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  • 6
    Electronic Resource
    Electronic Resource
    The saccus dorsalis of the rainbow trout, Salmo gairdneri Richardson (1976)
    Springer
    Cell & tissue research 167 (1976), S. 467-491 
    Details
    ISSN: 1432-0878
    Keywords: Saccus dorsalis, Salmo gairdneri Richardson ; Histology ; Ultrastructure ; Cytochemistry ; Enzyme-cytochemistry ; Autoradiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The saccus dorsalis of the brain of the rainbow trout, Salmo gairdneri Richardson, has been investigated by means of histological, cytochemical, enzyme-cytochemical, electron microscopical and autoradiographical techniques. The saccus dorsalis is a rostro-dorsal evagination of the diencephalic roof, and consists of a partly folded epithelial wall separating the cerebrospinal fluid from the meningeal matrix fluid. The well-developed vascular system around the epithelial wall, consisting of capillaries with different diameters, seems to be part of the pineal vascular system. No structures were found that may be involved in a possible mechanical or nervous blood flow control. The single-layered epithelium consists of highly specialized cells of one specific type. These cells are mainly characterized by infolded basal membranes, long microvilli of a peculiar shape, non-folded lateral membranes bordering intercellular spaces, apical concentrations of elongate and cupshaped macromitochondria, a basally located rough endoplasmic reticulum, an apically situated smooth endoplasmic reticulum and apical concentrations of micropinocytotic vesicles. Morphological evidence is presented of a multiple function of these cells: (1) fluid secretion, (2) extrusion of low molecular weight organic substances into the ventricular system, (3) uptake of high molecular weight substances, and (4) uptake of low molecular weight organic substances (aminergic neurotransmitters [GABA]) from the cerebrospinal fluid. The significance of light and dark cells is discussed. Indications of a possible innervation of the saccus dorsalis epithelial cells were not observed. The functional significance of the saccus dorsalis (possible analogue of the choroid plexus?) is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00215179
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