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  • 1
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    Dordrecht : Springer Science+Business Media B.V.
    Keywords: Life sciences ; Botany ; Life sciences ; Plant Sciences ; Springer eBooks
    Pages: : digital
    Edition: 3rd ed.
    ISBN: 9781402026867
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Coral reefs 6 (1988), S. 139-148 
    ISSN: 1432-0975
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract The reefless tract directly behind the ribbon reefs on the outer shelf off Cooktown supports a luxuriant growth of Halimeda that, during the Holocene, has developed into bioherms. These mounded biodies of unconsolidated sediment have formed banks that vary in height between 2 and 20 m. Combined shallow, high-resolution seismic reflection profiles and side-scan sonar have diferentiated three areas of biohermal complexes behind the ribbon reefs of Cooktown. Observations by SCUBA and submersible plus the sedimentology of the bioherms indicate that they are in situ accumulations. Evidence from dating of cores suggests that the Halimeda bioherms began to grow about 10 000 years B.P. and their growth has continued to the present time, even though their tops are presently restricted to a depth of -20 m. It is suggested that the origin and morphology of the bioherms are related to a specific hydrodynamic phenomenon, involving jets of nutrient-rich, upwelled oceanic water intruding onto the outer shelf via the narrow passes between the ribbon reefs, and forming eddies behind the ribbons.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2323
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Trois cent cinquante-cinq malades traités pour hyperthyroïdisme par thyroïdectomie subtotale ont été suivis jusqu'à 11 ans (5 ans en moyenne) après l'intervention en employant un système d'enregistrement sur ordinateur. Ce système repose sur une unité centrale de consultation hospitalière à qui les médecins de famille d'une large région géographique adressent les prélèvements sanguins. C'est ainsi que 1,379 tests fonctionnels thyroïdiens furent pratiqués chez 257 sujets, 50 autres malades ayant été perdus de vue et 48 traités pour hypothyroïdie. Quarante-trois des 132 sujets traités chirurgicalement et 81 des 125 opérés et traités par thyroxine ont montré des niveaux normaux de TSH pendant toute la période postopératoire. Les autres présentèrent au moins une fois un taux anormalement élevé de TSH. Quarante-sept pour cent des tests avec un taux normal de T4 avaient un taux élevé de TSH chez les opérés qui ne recevaient pas de T4. Chez les sujets qui recevaient de la thyroxine 46% d'entre eux qui présentaient un taux normal de TSH accusaient une élévation de T4. On peut conclure de cette étude que le système de contrôle proposé par les auteurs est valable et de coût satisfaisant. Des modifications sont cependant à envisager de façon à réduire le nombre des malades qui échappent au contrôle, de manière à améliorer la précision diagnostique des tests fonctionnels thyroïdiens et à définir la signification physiopathologique des anomalies mineures des taux de T4 et TSH chez les sujets euthyroïdiens.
    Abstract: Resumen Trescientos cincuenta y cinco pacientes hipertiroideos tratados con tiroidectomía subtotal han sido seguidos hasta por 11 años (promedio 5 años) mediante un registre de seguimiento computadorizado. El sistema esta basado en una consulta hospitalaria central; los pacientes son revisados regularmente por sus médicos generales en una amplia área geográfica y las muestras sanguíneas son enviadas al hospital. Cincuenta pacientes desaparecieron del seguimiento y 48 desarrollaron hipotiroidismo; 1379 pruebas de función tiroidea fueron evaluadas en los 257 pacientes resultantes. Cuarenta y tres de 132 pacientes tratados quirúrgicamente y 81 de 125 tratados quirúrgicamente y manejados con medicación a base de T4 exhibieron niveles normales de TSH a través de la totalidad del seguimiento. El resto de los pacientes presentó por lo menos en una ocasión un nivel elevado de TSH. Cuarenta y siete por ciento de las pruebas con nivel normal de T4 sérico presentó elevación de TSH en los pacientes que no recibian terapia con T4. En los pacientes que recibían tiroxina, el 46% de las pruebas con TSH normal exhibió elevación de T4. Se puede concluír que este tipo de seguimiento computadorizado es confiable y de buen costobeneficio. Se requiere su modificación con el fin de identificar los pacientes que se pierden en el seguimiento, de mejorar la precision diagnóstica de las pruebas de función tiroidea y de definir la significación patofisiológica de anormalidades menores de T4 y de TSH en pacientes por lo demás eutiroideos.
    Notes: Abstract Three hundred and fifty-five patients treated for hyperthyroidism by subtotal thyroidectomy have been followed for up to 11 years (mean 5 yr) by a computer-assisted follow-up register (WAFUR). The system is based on a central hospital clinic with patients being reviewed regularly by their general practitioners over a wide geographic area and blood samples being mailed to the hospital. After allowing for 50 patients who were lost to follow-up and 48 recalled because of hypothyroidism, 1,379 thyroid function tests were evaluated in the remaining 257 patients. Forty-three of 132 surgically treated patients and 81 of 125 surgically treated patients on replacement T4 therapy had normal TSH levels throughout the follow-up period. The other patients all had at least 1 elevated TSH level. In patients not receiving T4 therapy, 47% of tests with a normal serum T4 had elevation of TSH. In patients receiving thyroxine, 46% of tests with normal TSH showed a rise in T4. It is concluded that this computer-assisted thyroid follow-up system is reliable and cost-effective. Further modification is required to identify patients lost to follow-up, to improve the diagnostic accuracy of the thyroid function tests, and to define the pathophysiological significance of minor abnormalities in T4 and TSH in otherwise euthyroid patients.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1420-9136
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary With a view to modelling more realistically certain large-scale meteorological and oceanographic flows, some experiments are described in which temperature and velocity fields are measured in a rotating, differentially heated fluid annulus, and their dependence upon the imposed boundary conditions is investigated. It is demonstrated that with suitable construction of the annulus walls the strength of the zonal baroclinic motion may be chosen independently of the basic density stratification. Most of the measurements described are for the symmetric flow regime. In the experiments it is found that certain aspects of the observed temperature and flow fields — in particular the basic stratification and the slope of the isotherms — agree reasonably well with theoretical estimates.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Microtubules and their associated proteins play a prominent role in many physiological and morphological aspects of brain function. Abnormal deposition of the microtubule-associated proteins (MAPs), MAP2 and γ, is a prominent aspect of Alzheimer's disease. MAP2 and γ are heat-stable phosphoproteins subject to high rates of phosphorylation/dephosphorylation. The phosphorylation state of these proteins modulates their affinity for tubulin and thereby affects the structure of the neuronal cytoskeleton. The dinoflagellate toxin okadaic acid is a potent and specific inhibitor of protein phosphatases 1 and 2A. In cultured rat cortical neurons and a human neuroblastoma cell line (MSN), okadaic acid induces increased phosphorylation of MAP2 and γ concomitant with early changes in the neuronal cytoskeleton and ultimately leads to cell death. These results suggest that the diminished rate of MAP2 and γ dephosphorylation affects the stability of the neuronal cytoskeleton. The effect of okadaic acid was not restricted to neurons. Astrocytes stained with antibodies to glial fibrillary acidic protein (GFAP) showed increased GFAP staining and changes in astrocyte morphology from a flat shape to a stellate appearance with long processes.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Aging and apolipoprotein E (APOE) isoform are among the most consistent risks for the development of Alzheimer's disease (AD). Metabolic factors that modulate risk have been elusive, though oxidative reactions and their by-products have been implicated in human AD and in transgenic mice with overt histological amyloidosis. We investigated the relationship between the levels of endogenous murine amyloid β (Aβ) peptides and the levels of a marker of oxidation in mice that never develop histological amyloidosis [i.e. APOE knockout (KO) mice with or without transgenic human APOEɛ3 or human APOEɛ4 alleles]. Aging-, gender-, and APOE-genotype-dependent changes were observed for endogenous mouse brain Aβ40 and Aβ42 peptides. Levels of the oxidized lipid F2-isoprostane (F2-isoPs) in the brains of the same animals as those used for the Aβ analyses revealed aging- and gender-dependent changes in APOE KO and in human APOEɛ4 transgenic KO mice. Human APOEɛ3 transgenic KO mice did not exhibit aging- or gender-dependent increases in F2-isoPs. In general, the changes in the levels of brain F2-isoPs in mice according to age, gender, and APOE genotype mirrored the changes in brain Aβ levels, which, in turn, paralleled known trends in the risk for human AD. These data indicate that there exists an aging-dependent, APOE-genotype-sensitive rise in murine brain Aβ levels despite the apparent inability of the peptide to form histologically detectable amyloid. Human APOEɛ3, but not human APOEɛ4, can apparently prevent the aging-dependent rise in murine brain Aβ levels, consistent with the relative risk for AD associated with these genotypes. The fidelity of the brain Aβ/F2-isoP relationship across multiple relevant variables supports the hypothesis that oxidized lipids play a role in AD pathogenesis, as has been suggested by recent evidence that F2-isoPs can stimulate Aβ generation and aggregation.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: A single nucleotide polymorphism that results in an amino acid change (Q7R) has been identified in the Saitohin (STH) gene and was initially found to be over-represented in the homozygous state in subjects with late-onset Alzheimer's disease (AD). More extensive studies provide limited support for the association with AD, but confirm an association of the Q allele with progressive supranuclear palsy and argyrophilic grain disease. A homologous sequence was found in the appropriate location of the rat and mouse tau genes, but there was no open reading frame allowing STH expression in these species, suggesting relatively recent evolution of this gene. In some non-human primates, the STH gene was identified, and this was found to differ from the human gene at two of 128 amino acids. All primates in which the STH gene was identified were homozygous for the R allele of STH, suggesting this is the ancestral allele. This observation was surprising, in that the Q allele is more common in human populations, and raises the possibility that natural selection has operated to favor individuals carrying this allele. The STH polymorphism is part of the tau gene haplotype, of which two major variants exist in human populations, the Q being part of the H1 haplotype and the R part of the H2 haplotype. More detailed studies confirm the H2 haplotype to be the ancestral tau gene. This situation is reminiscent of the evolution of the apolipoprotein (ApoE) gene, another locus that is potentially important for the risk of development of AD.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Elevated levels of p25 and constitutive activation of CDK5 have been observed in AD brains. This has led to the hypothesis that increased p25 levels could promote neurofibrillary tangles (NFT) through CDK5-mediated hyperphosphorylation of tau, the principal component of NFTs. We examined p25 immunoreactivity in brains from sporadic and familial AD cases, as well as other neurologic diseases that exhibit NFT, such as Down's syndrome (DS), Pick's disease (Pick), corticobasal degeneration (CBD), progressive supranuclear palsy (PSP), frontotemporal dementia (FTD). Neither the p25 immunoreactivity nor the p25/p35 ratio was elevated in the AD brains or in the other tauopathies (n = 34) compared with controls (n = 11). Although Aβ peptides have been suggested to activate calpain-mediated cleavage of p35 to p25 in cultured neurons, p25 levels in brains of TgCRND8 mice, which express high levels of brain Aβ peptides, were similar to those of non-Tg littermates. Our data suggest that high Aβ levels in brain do not activate p35 proteolysis, and p25 is unlikely to be a causative agent for NFT formation in AD or other tauopathies.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Neurofibrillary tangles are composed of insoluble aggregates of the microtubule-associated protein tau. In Alzheimer's disease the accumulation of neurofibrillary tangles occurs in the absence of tau mutations. Here we present mice that develop pathology from non-mutant human tau, in the absence of other exogenous factors, including β-amyloid. The pathology in these mice is Alzheimer-like, with hyperphosphorylated tau accumulating as aggregated paired helical filaments. This pathologic tau accumulates in the cell bodies and dendrites of neurons in a spatiotemporally relevant distribution.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Hyperphosphorylated tau (PHF-tau) is the major constituent of paired helical filaments (PHFs) from Alzheimer's disease (AD) brains. This conclusion has been based largely on the creation and characterization of monoclonal antibodies raised against PHFs, which can be classified in three categories: (a) those recognizing unmodified primary sequences of tau, (b) those recognizing phosphorylation-dependent epitopes on tau, and (c) those recognizing conformation-dependent epitopes on tau. Recent studies have suggested that the antibodies recognizing primary sequence and phosphorylation-dependent epitopes on tau are unable to distinguish between normal adult biopsy tau and PHF-tau. We now present evidence for a new fourth class of monoclonal antibodies recognizing conformation-dependent phosphoepitopes on tau, typified by TG-3, a monoclonal antibody raised to PHFs from AD brain homogenates. Studies using a series of deletional tau mutants, site-directed tau mutants, and synthetic peptides enable the precise epitope mapping of TG-3. Additional studies demonstrate that TG-3 reacts with neonatal mouse tau and PHF-tau but does not recognize adult mouse tau or tau derived from normal human autopsy or biopsy tissue. Further investigation reveals that TG-3 recognizes a unique conformation of tau found almost exclusively in PHFs from AD brains.
    Type of Medium: Electronic Resource
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