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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Diabetologia 28 (1985), S. 452-457 
    ISSN: 1432-0428
    Keywords: Alloxan-induced diabetes ; myocardium ; hyperglycaemia ; calcium ; magnesium ; ATPase activity ; lysosomal enzymes ; diabetic cardiomyopathy ; rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Biochemical and myocardial functional changes were determined in rabbits made diabetic with alloxan (100mg/kg, intravenously, two injections 24 h apart). Alloxan-induced diabetes was characterized by a state of hypoinsulinaemia and hyperglycaemia. After 10 weeks of diabetes, significant decreases in heart and left ventricular weights as well as increased serum and heart triglycerides and cholesterol were observed in the diabetic animals (p 〈 0.05). In addition, left ventricular pressure, heart rate and rate of left ventricular pressure development were all decreased in the animals. The diabetic state was also associated with a slight elevation in myocardial calcium and a significant decrease in magnesium levels (p 〈 0.05). Subcellular fractionation of diabetic hearts indicated the presence of alterations in myofibrillar and sarcoplasmic reticulum marker enzymes (p 〈 0.05). Among the lysosomal enzymes, measured, N-acetyl-β-glucosaminidase activity was significantly increased in the homogenates of diabetic left ventricles (p 〈 0.05). These alterations in hearts of diabetic rabbits may be responsible for some aspects of diabetic cardiomyopathy.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0428
    Keywords: Keywords Aorta ; endothelin ; insulin ; streptozotocin diabetic rat ; vanadate.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Although insulin has been shown to raise plasma concentrations of endothelin (ET) and up regulate vascular smooth muscle ETA receptor expression, the interaction of vanadate, an insulinomimetic agent, with the vascular ET system has not been investigated. We compared the effects of oral vanadate treatment (0.5 mg/ml; p. o.) and insulin infusion (12 mU · kg–1· min–1 s. c.) for two weeks on plasma ET concentrations and vascular responses to endothelin-1 (ET-1) and the α-1 adrenoceptor agonist, methoxamine, in aortic ring preparations from streptozotocin (STZ) diabetic and non-diabetic adult male Sprague-Dawley rats. Plasma ET concentrations were lower (p 〈 0.01) in STZ diabetic rats compared with normal control rats. Insulin and vanadate treatment restored plasma ET to normal (p 〈 0.01) in STZ rats and increased ET concentrations in the control (p 〈 0.05) group. Higher maximal tension responses to both ET-1 (p 〈 0.01) and methoxamine (p 〈 0.05) were present in STZ rats in both endothelium intact and denuded aortic preparations compared with the control group. Both insulin and vanadate treatment returned these responses to normal. It is concluded that low plasma concentrations of insulin and high plasma glucose in STZ diabetic rats are accompanied by lower concentrations of plasma ET. Insulin and vanadate treatment restores diminished plasma ET to control concentrations and attenuates exaggerated agonist(s)-evoked vascular smooth muscle responses in STZ-induced diabetic rats. In addition to well known beneficial metabolic effects, insulin and vanadate may beneficially affect cardiovascular regulation in the STZ diabetic rat by correcting abnormal ET activity. [Diabetologia (1998) 41: 1233–1240]
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0428
    Keywords: Diabetes mellitus ; vanadyl sulphate ; glucose ; pancreas ; streptozotocin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Recent studies have demonstrated the insulin-like effects of oral vanadyl sulphate in the streptozotocin-diabetic rat, including the amelioration of hyperglycaemia and the prevention of diabetes-related cardiac and adipose tissue dysfunction. However, the possibility that vanadyl treatment, routinely initiated at 3 days after the induction of diabetes, had prevented the full cytotoxic destruction of the beta cell, and thus accounted for the apparent anti-diabetic properties of vanadyl was questioned. Hence in the present study, we examined the effectiveness of vanadyl sulphate as a glucose-lowering and anti-diabetic agent when administration was delayed from the time of induction of diabetes. Male Wistar rats were injected with a single intravenous dose of streptozotocin (55 mg/kg). Vanadyl sulphate was administered in the drinking water at a concentration of 0.75 mg/ml from 3, 10 and 17 days after the streptozotocin injection and treatment was then maintained for 5 months. Vanadyl intake was accompanied by lowered serum levels of triglyceride and cholesterol with no associated enhancement in circulating insulin. Vanadyl-treated diabetic animals showed improved glucose tolerance while insulin release in vivo was still markedly lower than in non-diabetic rats. Adipose tissue function, as expressed by basal and epinephrine-stimulated lipolysis in isolated adipose tissue, was also normalized in vanadyl-treated diabetic animals. These responses were all observed whether vanadyl treatment was initiated 3, 10 or 17 days after induction of diabetes. Finally, prolonged treatment with vanadyl sulphate (in this case up to 5 months) did not cause any apparent hepatic toxicity as assessed histologically. Diabetes-induced morphological changes in the kidney were also prevented by vanadyl treatment. Thus, these findings support the concept that the efficacy of vanadyl treatment is unrelated to protection from the acute toxic effects of streptozotocin on pancreatic beta cells. Further, these studies provide additional support for the notion suggested in earlier studies that either improved pancreatic function may result from the alleviation of hyperglycaemia by vanadium treatment or that some residual pancreatic function which in itself is insufficient to prevent the onset and progression of the diabetic state may contribute to an effective response to administered vanadium.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0568
    Keywords: Vasculature ; Wound healing ; Limb bud ; Chick
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Experimental analyses examining pattern formation in the developing chick limb have concentrated on the skeleton, muscles and nerves, and have rarely considered blood vessels. To investigate the relationship between the vasculature and limb development, posterior amputations were performed on 3.5–4 day chick limb-buds. It has been shown that the removal of the posterior half alters the developmental fate of the anterior tissue: it becomes necrotic and fails to differentiate into the complement of skeletal parts predicted by fate maps. The possibility that this developmental failure results from interference with the future arterial supply was examined by Indian ink injection between 3–48 h after operation. Scanning electron microscopy (SEM) and resin histology were used to examine the wound repair at similar post-operative intervals. Results from the Indian ink injections showed that within 6 h of operation a collateral circulation was established by means of a branch from the truncated primary subclavian artery. The capillary density in the operated limbs appeared normal when compared to the contralateral limb. The results support the view that the poor developmental performance of the anterior half is due to removal of the zone of polarising activity (ZPA) rather than to experimentally-induced alteration to the vascular supply. Histological and SEM examination of the wound healing process showed that epithelialization of the cut surface occurred within 24 h, and that the peridermal cells of the bilayered ectoderm appeared to initiate the regrowth. The wound site was not visible 48 h after operation, showing that wound healing at these developmental ages occurs quickly, with no scar tissue formation. These results show that the vasculature in the developing limb is labile, and that the cell death resulting from posterior-half amputation is not due to vascular insufficiency or ischaemia. In addition, this study of wound healing demonstrates the role of the ectoderm in establishing an avascular margin in the subjacent mesenchyme.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 142 (1938), S. 353-354 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] IN a previous letter to NATURE1, evidence was given that some atmospherics are reflected at the ionosphere. Further oscillographs obtained with an improved technique (see Figs. 1 and 2—photographic records on a rapidly moving film of the electric field of atmospherics) have led ...
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Electroanalytical Chemistry 148 (1983), S. 17-24 
    ISSN: 0368-1874
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 105 (1996), S. 3883-3891 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The energies and dispersions of the image states and quantum well electronic states in layers of Xe and Kr on a Ag(111) substrate were determined by angle-resolved two-photon photoemission (ARTPPE). For Xe, we measured binding energies of unoccupied electronic states for 1–9 layers and their parallel dispersion out to 4 layers. We measured the binding energies for a monolayer of Kr and dispersions for one and two layers. The n=2 and n=3 image states of the bare metal evolve into quantum well states of the layer (states of the Xe conduction band discretized by the boundary conditions of a 2-D slab) at higher Xe thicknesses, where the n=2,3 states exhibit both a perpendicular and parallel dispersion similar to that of the bulk Xe conduction band. The n=1 state appears to evolve with coverage as an image state screened by the Xe layer, with appreciable electron density in the vacuum. A continuum dielectric model (modified image state picture) reproduces the gross trends in the data, while an explicit quantum well analysis is used to extract the bulk Xe conduction band dispersion. A simple model which takes into account the band structures of the substrate and the overlayer, as well as the image potential, gives good agreement with the binding energy data. The combination of high energy and momentum resolution along both the surface parallel and surface normal yields very precise measurements of the bulk Xe conduction band as well as information about the behavior of conduction band electrons at interfaces. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Weed research 16 (1976), S. 0 
    ISSN: 1365-3180
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Taxonomy describes and classifies (i.e. maps) the diversity of nature. The most useful classifications are those that permit the delimitation, and subsequent identification, of species in such a way that they exhibit genetic differences and ecological preferences. However, all classifications have limitations for weed scientists. Genetic variation within species may be just as important as differences between species to the development of weed control practices. Because traditional concepts, such as species, variety and ecotype, cannot fully reflect the products of evolutionary processes, alternative taxonomic or para-taxonomic representations of variation are considered. The dependence of plant nomenclature on these inherently limited taxonomic concepts is also discussed, and ways are suggested of minimizing the resultant degree of instability in the scientific names of weeds. The evolutionary responses of weeds to changing conditions suggest that although selection within populations is important, changes in the species composition of a weed flora may be a more common response to selection. Recombination through hybridization can be particularly significant, especially in the evolution of weeds which are genetically close to the crop species.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Physical Chemistry 48 (1997), S. 711-744 
    ISSN: 0066-426X
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract Two-photon photoemission is a promising new technique that has been developed for the study of electron dynamics at interfaces. A femtosecond laser is used to both create an excited electronic distribution at the surface and eject the distribution for subsequent energy analysis. Time- and momentum-resolved two-photon photoemission spectra as a function of layer thickness fully determine the conduction band dynamics at the interface. Earlier clean surface studies showed how excited electron lifetimes are affected by the crystal band structure and vacuum image potential. Recent studies of various insulator/metal interfaces show that the dynamics of excess electrons are largely determined by the electron affinity of the adsorbate. In general, electron dynamics at the interface are influenced by the substrate and adlayer band structures, dielectric screening, and polaron formation in the two-dimensional overlayer lattice.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Steroid Biochemistry 25 (1986), S. 66 
    ISSN: 0022-4731
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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