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  • 1
    Keywords: Medicine ; Neurosciences ; Ophthalmology ; Neurobiology ; Biomedicine ; Neurosciences ; Ophthalmology ; Neurobiology ; Springer eBooks
    Description / Table of Contents: 1. Introduction -- 2. Fundamental Retinal Circuitry for Circadian Rhythms -- 3. Circadian photoreception: from phototransduction to behaviour -- 4. Role of Melatonin and Dopamine in the Regulation of Retinal Circadian Rhythms -- 5. Circadian Organization of the Vertebrate Retina -- 6. Rhythmicity of the Retinal Pigment Epithelium -- 7. Retinal Circadian Rhythms in Mammals Revealed Using Electroretinography -- 8. Circadian Clock and Light Induced Retinal Damage -- 9. Circadian Rhythms and Vision in Zebrafish -- 10. Circadian Modulation of the Limulus Eye for Day and Night Vision -- 11. Molluscan Ocular Pacemakers: Lessons Learned. ℗ ℗ ℗ ℗ ℗ ℗ ℗ ℗ ℗
    Abstract: The retina plays a critical role in the organization of the circadian system by synchronizing the braiń€™s central clock with the external day through transduction of the daily light/dark cycle.℗ However, the substantial variation in luminance imposed on the retina between day and night also poses a challenge to its role as a sensory tissue ́€“ how is it possible to faithfully encode the enormous dynamic range of luminance that can exceed 10 orders of magnitude? The Retina and Circadian Rhythms summarizes the knowledge accumulated over the last 30 years about the organization of the retinal circadian clock in many different species, concentrating on the roles that this circadian system plays in retinal function. About the Series: The Springer Series in Vision Research is a comprehensive update and overview of cutting edge vision research, exploring, in depth, current breakthroughs at a conceptual level. It details the whole visual system, from molecular processes to anatomy, physiology and behavior and covers both invertebrate and vertebrate organisms from terrestrial and aquatic habitats. Each book in the Series is aimed at all individuals with interests in vision including advanced graduate students, post-doctoral researchers, established vision scientists and clinical investigators.The series editors are N. Justin Marshall, Queensland Brain Institute, The University of Queensland, Australia and Shaun P. Collin, Neuroecology Group within the School of Animal Biology and the Oceans Institute at the University of Western Australia
    Pages: VIII, 238 p. 50 illus., 33 illus. in color. : online resource.
    ISBN: 9781461496137
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  • 2
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In mice, there is evidence suggesting that the development of head and trunk structures is organized by distinctly separated cell populations. The head organizer is located in the anterior visceral endoderm (AVE) and the trunk organizer in the node and anterior primitive streak. In ...
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Cancer causes & control 3 (1992), S. 283-288 
    ISSN: 1573-7225
    Keywords: Cancer ; childhood ; cluster ; leukemia ; nuclear plant ; United Kingdom
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1573-6822
    Keywords: atherosclerosis ; dinitrotoluences ; vascular smooth muscle cells ; DNA synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Studies were conducted to determine if in vivo exposure to dinitrotoluenes (DNT), which is associated with circulatory disorders of atherosclerotic etiology in humans, is associated with alterations of vascular smooth muscle cells (SMC) consistent with the atherogenic process. Sprague-Dawley rats (150-180 g) were injected IP for 5 days/week for 8 weeks with 2,4- or 2,6-DNT (0.5, 5, or 10 mg/kg) or medium chain triglyceride (MCT) oil. Histopathologic evaluation of aortae from animals exposed to either isomer showed dysplasia and rearrangement of SMC at all doses tested. Reduced 3H-thymidine incorporation was observed in primary cultures of aortic SMC from DNT-exposed animals relative to vehicle controls. This inhibitory response was maintained for up to two passages in culture after which a significant increase in thymidine incorporation was observed. Exposure of SMC from naive animals to DNT in vitro (1–100 µM) did not alter the extent of thymidine incorporation in cycling or growth-arrested cultures. In contrast, exposure to 2,4- or 2,6-diaminotoluene (DAT) (1–100 µM), carcinogens which share toxic metabolic intermediates in common with DNT, inhibited replicative DNA synthesis and stimulated unscheduled DNA synthesis in cycling and growth-arrested cultures of SMC, respectively. Our results suggest that modulation of DNA synthesis in aortic SMC by DNT metabolites generated in vivo contribute to the development of vascular lesions.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Artificial intelligence review 12 (1998), S. 347-391 
    ISSN: 1573-7462
    Keywords: natural language processing ; n-gram models ; probability ; statistics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract We present a review of some recently developed techniques in the field of natural language processing. This area has witnessed a confluence of approaches which are inspired by theories from linguistics and those which are inspired by theories from information theory: statistical language models are becoming more linguistically sophisticated and the models of language used by linguists are incorporating stochastic techniques to help resolve ambiguities. We include a discussion about the underlying similarities between some of these systems and mention two approaches to the evaluation of statistical language processing systems.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-6865
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Immunocytochemical and histochemical properties of macrophages present in the subcutaneous chronic inflammatory responses surrounding adultOnchocerca volvulus (nodules) in human tissues were examined. Macrophages with strong non-specific esterase (NSE) and acid phosphatase (AcPase) activities but weak adenosine triphosphatase (ATPase) activity and HLA-DR expression (NSE+++, AcPase+++, ATPase−/+, HLA-DR−/+) were present in the centre of nodules. Many of the cells adhering to the surface of worms were NSE+++, AcPase+++, ATPase−, HLA-DR+++. The inner zone of the fibrous capsule of nodules contained macrophages with the profile NSE+++, AcPase−, ATPase−/+, HLA-DR−/+. A fourth type, NSE+++, AcPase−/+, ATPase−/+, HLA-DR+++, was located in the outer zone of the capsule, frequently within perivascular accumulations of macrophages, lymphocytes and plasma cells. Active fibroblasts were identified at the inner edge of the fibrous capsule by alkaline phosphatase staining. A feature of all nodules examined was the presence of lipid-filled macrophages, demonstrated by Oil Red O stain; these cells were usually situated in zones adjacent to the centre of nodules, and were of the NSE++, AcPase++, ATPase−/+, HLA-DR−/+ type. Lipid accumulation was not found to be related to the clinical status of the patients studied. The origin and functional significance of this lipid is unknown.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-6865
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Previous studies of the normal human colorectum by lectin histochemistry have used a mixture of tissues, including those derived from colons harbouring neoplasia and inflammatory bowel diseases. In the current investigation, tissues from patients without either of these conditions have been examined with a wide panel of lectins, encompassing specificities directed against both N- and O-linked sequences, using an avidin peroxidase revealing system and evaluated with a semiquantitative scoring method. The results of binding of these lectins have been compared with those seen in the resection margins of (at least 5 cm away from) colorectal carcinomas. Consistent regional variations were noted between right- and left-sided colonie tissues, with more diverse glycan structures and a greater sialyl content in the distal colon. There was evidence of graduation of formation of oligosaccharide chains in developing crypts, possibly related to the maturation and expression of glycosyl transferases responsible for the incorporation of mannose residues of N-linked oligosaccharides and of N-acetylgalactosamine and N-acetylglucosamine. Comparison with previous reports has revealed some variations, possibly related to tissue fixation and processing and to lectin concentrations employed, which raises the question of standardization of methodologies in lectin histochemical investigations.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-6865
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Microwave irradiation was investigated as a pretreatment toin situ hybridization on formalin-fixed, paraffin-embedded tissue. Two probe/tissue systems were used: a single-stranded RNA probe for the detection of measles virus nucleocapsid genome in subacute sclerosing panencephalitis brain tissue, and a double stranded DNA probe for chicken anaemia virus in thymus of chicken infected with the virus. Microwaving, when used as sole pretreatment, was not as effective as the more traditional enzyme pretreatments forin situ hybridization. However, when used in combination with existing pretreatments, a significant increase was found in hybridization signal in both brain and thymus tissue. This was emphasized when combination enzyme/microwave pretreatments were used prior to detection of measles virus byin situ hybridization in a series of five archival subacute sclerosing panencephalitis cases. The use of microwave irradiation would be recommended as a means of supplementingin situ hybridization methods, especially when using long-term formalin fixed paraffin-embedded tissue.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-136X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The function of carbonic anhydrase (CA) in the Red Rock Crab,Cancer productus Randall, was investigated. CA activity was found to varying degrees in the gills and many other tissues but not in hemolymph. Crabs injected with acetazolamide, a specific CA inhibitor, demonstrated a significant hemolymph acidosis. Hemolymph CO2 tension ( $$Pa_{CO_2 }$$ ) and CO2 content ( $$Ca_{CO_2 }$$ ) also increased and remained significantly elevated for 96 h following treatment. No significant changes could be detected in either hemolymph oxygenation or ionic status (except for HCO 3 − ) as a result of acetazolamide treatment. Crabs treated with acetazolamide, and also exposed to air, exhibited a more pronounced hemolymph acidosis with significantly increased respiratory ( $$P_{CO_2 }$$ ) and metabolic (lactate) components compared with the control group. Upon reimmersion acetazolamide treated crabs showed a slower recovery of hemolymph pH compared with the control group and no significant removal of the total CO2 load induced by air exposure. No significant differences between experimental and control groups during air exposure and recovery could be detected in hemolymph oxygenation, ionic status, NH3+NH 4 + levels or respiratory and cardiac pumping frequency and so the effects of acetazolamide treatment were apparently limited to CO2 removal across the gills. These results indicate that branchial CA facilitates the removal of CO2 from the hemolymph of SW adaptedC. productus largely by catalyzing the dehydration of hemolymph HCO 3 − to molecular CO2 at the gill. It is also recognized that gill CA may also serve to hydrate molecular CO2 to H+ and HCO3/− for use as counterions for ionic uptake mechanisms. Crab gill CA thus appears to play an important role in CO2 excretion as well as hemolymph ionic regulation.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-136X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The oxygen and carbon dioxide transporting properties of the haemolymph from an amphibious Australian crab,Holthuisana transversa were investigated. Within the temperature range 15 to 35°C increasing temperature markedly decreased oxygen affinity (ΔH=−54 kJ·mol−1). The Bohr effect was small at all temperatures with a mean value of −0.13. Over the temperature range 15–35°C there was a significant increase in the cooperativity of oxygen binding. Changing the concentration of Ca,l-lactate or haemocyanin in the haemolymph could elicit no significant change in either O2 affinity or cooperativity of O2 binding. There was no evidence in support of a specific effect of CO2 on oxygen affinity of either non-dialysed or dialysed haemolymph. The amount of CO2 that could be carried byH. transversa haemolymph was significantly reduced by increased temperature (approx. 14 to 12.5 mmol·l−1 CO2). Comparisons of oxygenated and deoxygenated haemolymph at a fixed pH were unable to demonstrate the presence of a significant Haldane effect. Combining data from oxygenated and deoxygenated haemolymph the buffer value was calculated to be in the range −6.2 to −8.5 mmol·l−1 HCO 3 − ·pH unit−1. The insensitivity ofH. transversa haemocyanin function to all modulating influences except temperature is discussed with respect to the ecology of this crab.
    Type of Medium: Electronic Resource
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