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  • 1
    Electronic Resource
    Electronic Resource
    Effect of 1,25-dihydroxycholecalciferol on sarcoplasmic reticulum calcium transport in strontium-fed chicks (1983)
    Springer
    Calcified tissue international 35 (1983), S. 190-194 
    Details
    ISSN: 1432-0827
    Keywords: 1,25-Dihydroxyvitamin D3 ; Calcium transport ; Sarcoplasmic reticulum ; Muscle ; Strontium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Feeding of chicks with strontium, an inhibitor of 1,25-dihydroxycholecalciferol synthesis in kidney, during 7 days, significantly depressed the initial rate of calcium uptake and calcium storing capacity of sarcoplasmic reticulum membranes from skeletal muscle. Oral administration of 1,25(OH)2D3 to strontium-fed animals returned calcium transport values to normal. The changes observed could not be related to differences in the relative proportions of transport ATPase and calcium binding proteins. The results are consistent with a role of 1,25(OH)2D3 in muscle function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405030
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  • 2
    Electronic Resource
    Electronic Resource
    Potentiation of the effects ofSolanum malacoxylon extracts on rat intestinal phosphate and calcium absorption by incubation with ruminal fluid (1978)
    Springer
    Calcified tissue international 26 (1978), S. 215-219 
    Details
    ISSN: 1432-0827
    Keywords: Solanum malacoxylon ; Vitamin D metabolites ; Rickets ; Phosphate ; Calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The effects of a partially purified aqueous extract ofSolanum malacoxylon (SM) leaves and of an SM extract incubated with ruminal fluid (RF) prior to administration on intestinal phosphate and calcium absorption in rachitic rats were compared with 1α, 25-dihydroxy-vitamin D3[1α,25-(OH)2-D3] using a duodenal loop in situ method. The time course responses elicited by both extracts were qualitatively similar to that of 1α, 25-(OH)2-D3. However, a single dose of SMRF was significantly more effective in stimulating32P absorption than an equivalent dose of SM. Part of this difference can be accounted for by incomplete saturation of the phosphate transport system with the level of SM employed. Treatment with rumen potentiated the effects of SM on45Ca absorption to a lesser extent. Extraction of SMRF with nonpolar organic solvents and purification of the lipid extract by chromatography on Silica Gel G thin-layer plates and on Sephadex LH-20 columns yield two fractions which promote intestinal32P absorption. The bioactive fraction eluting first from the Sephadex LH-20 column migrates similarly as 1α,25-(OH)2-D3. The greater effectiveness of SMRF extracts on intestinal phosphate and calcium absorption may be tentatively attributed to the release of 1α,25-(OH)2-D3 from the corresponding glycoside, shown previously to be present in SM, and to steroid modification during incubation with rumen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02013261
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  • 3
    Electronic Resource
    Electronic Resource
    The effect of cholecalciferolin vivo on proteins and lipids of skeletal muscle from rachitic chicks (1983)
    Springer
    Calcified tissue international 35 (1983), S. 798-805 
    Details
    ISSN: 1432-0827
    Keywords: Vitamin D deficiency ; Muscle mitochondria ; Actomyosin ; Sarcoplasmic reticulum ; Phospholipids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The protein and lipid constituents of skeletal muscle subcellular fractions isolated from chicks fed a vitamin D-deficient diet for 3 weeks and chicks repleted with cholecalciferol (vitamin D3) were analyzed. Administration of the sterol markedly altered the protein composition of mitochondria. The changes were localized in the inner membranes and consisted of a modification of the relative amounts of proteins of approximate mol wt of 83,000, 58,000, 42,000, and 34,000. In addition, treatment with vitamin D3 modified the distribution pattern of components of the actomyosin contractile complex. An increase in actin and troponin C was particularly noticeable. No differences between rachitic and treated animals were detected in the protein composition of sarcoplasmic reticulum membranes and postmicrosomal soluble fraction. A significant increase in the phospholipid content of sarcoplasmic reticulum (P〈0.05), and to a lesser extent of mitochondria, was observed in repleted chicks. The relative proportions of individual phospholipids, however, were not changed. Injection of an acute dose of cholecalciferol to chicks less severely depleted in vitamin D significantly stimulated the incorporation of32PO4 in vivo to muscle homogenates, mitochondria, and sarcoplasmic reticulum (P〈0.05). As the increases in specific activities of sarcoplasmic inorganic P and membrane lipid P were similar whereas that of serum remained unchanged, the results are compatible with the idea that vitamin D3 stimulates phosphate fluxes across muscle membranes. The sterol produced minor modifications in the fatty acid composition of sarcoplasmic reticulum (P〈0.05).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405126
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  • 4
    Electronic Resource
    Electronic Resource
    Reversal of decreased phosphorylation of sarcoplasmic reticulum calcium transport ATPase by 1,25-dihydroxycholecalciferol in experimental uremia (1983)
    Springer
    Calcified tissue international 35 (1983), S. 195-201 
    Details
    ISSN: 1432-0827
    Keywords: 1,25-Dihydroxycholecalciferol ; Uremia ; Muscle phosphorylation ; Sarcoplasmic reticulum ; ATPase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary When compared to that from shamoperated controls, sarcoplasmic reticulum isolated from skeletal muscle of uremic rabbits had a lower rate of calcium uptake and storing capacity. In vivo administration of 1,25-dihydroxycholecalciferol [1,25(OH)2D3] restored the values in uremic animals toward normal. To obtain information about the mechanisms responsible for these differences, phosphorylation of the calcium transport ATPase was studied. The steady-state levels of phosphoprotein in uremic membranes were lower and returned to normal when the secosteroid was administered. Electrophoresis of the membranes phosphorylated with32P-inosine triphosphate (32P-ITP) showed that the differences were related to a 100,000 dalton protein. The rate of phosphoprotein formation, determined with32P-ITP and at 0°C, was considerably lower in uremic than in control animals. Pretreatment with 1,25(OH)2D3 prevented this change. The hypothesis is advanced that the vitamin D metabolite affects the steady-state concentration and rate constant of formation of active sites in the Ca-ATPase. These results may partly explain the altered Ca transport function of the sarcoplasmic reticulum in experimental uremia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02405031
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  • 5
    Electronic Resource
    Electronic Resource
    In Vivo Treatment with Calcitriol (1,25(OH)2D3) Reverses Age-Dependent Alterations of Intestinal Calcium Uptake in Rat Enterocytes (1999)
    Springer
    Calcified tissue international 64 (1999), S. 173-178 
    Details
    ISSN: 1432-0827
    Keywords: Key words: 1,25(OH)2D3— Aging — Enterocytes — Calcium uptake — cAMP pathways.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. The vitamin D endocrine system has been involved in the impairment of intestinal calcium absorption during aging. Alterations in the nongenomic mechanism of calcitriol (1,25-dihydroxy-vitamin D3; [1,25(OH)2D3] have been recently evidenced. In enterocytes isolated from aged rats, 1,25(OH)2D3 stimulation of Ca2+ channels through the cAMP/PKA pathway is blunted. We have now investigated whether in vivo administration of calcitriol to senescent rats reverses the absence of hormonal effects in isolated intestinal cells. In enterocytes from 20–24-month-old rats given 1,25(OH)2D3 for 3 days (30 ng/100 g bw/day), calcitriol (10−10 M, 3–5 minutes) stimulated Ca2+ uptake and intracellular cAMP to the same degree and protein quinase A (PKA) activity to a lesser degree than in enterocytes from young animals. Significantly higher basal levels of cAMP and PKA detected in enterocytes from old rats were not affected by prior injection of animals with 1,25(OH)2D3. When the aged rats were injected with 25(OH)D3, similar Ca2+ influx, cAMP, and PKA responses to in vitro stimulation with calcitriol were obtained. 1,25(OH)2D3-dependent changes in Ca2+ uptake by enterocytes from both young and old rats treated with calcitriol were totally suppressed by the cAMP antagonist Rp-cAMPS, whereas the response to the agonist Sp-cAMPS was markedly depressed in aged animals. These results suggest that intestinal resistance to nongenomic 1,25(OH)2D3 stimulation of duodenal cell Ca2+ uptake develops in rats upon aging and show that in vivo administration of 1,25(OH)2D3 or its precursor to senescent rats restores the ability of the hormone to stimulate duodenal cell calcium influx through the cAMP messenger system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900598
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  • 6
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    The relationship between pain, analgesics and survival in patients with advanced cancer; a secondary data analysis of the international European palliative care Cancer symptom study. (2019)
    Springer
    Details
    Publication Date: 2019-12-21
    Print ISSN: 0031-6970
    Electronic ISSN: 1432-1041
    Topics: Chemistry and Pharmacology , Medicine
    Published by Springer
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  • 7
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    MAP kinases in proliferating human colon cancer Caco-2 cells (2009)
    Springer
    Details
    Publication Date: 2009-03-20
    Print ISSN: 0300-8177
    Electronic ISSN: 1573-4919
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Published by Springer
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  • 8
    Electronic Resource
    Electronic Resource
    Super-radiant surface emission from a quasi-cavity hot electron light emitter (1999)
    Springer
    Optical and quantum electronics 31 (1999), S. 183-190 
    Details
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract The Hot Electron Light Emitting and Lasing in Semiconductor Heterostructure (HELLISH-1) device is a novel surface emitter which utilises hot carrier transport parallel to the layers of a Ga1−xAlxAs p-n junction incorporating a single GaAs quantum well on the n-side of the junction plane. Non-equilibrium electrons are injected into the quantum well via tunnelling from the n-layer. In order to preserve the charge neutrality in the depletion region, the junction undergoes a self-induced internal biasing. As a result the built-in potential on the p-side is reduced and hence the injection of non- equilibrium holes into the quantum well in the active region is enhanced. The work presented here shows that a distributed Bragg reflector grown below the active region of the HELLISH device increases the emitted light intensity by two orders of magnitude and reduces the emission line-width by about a factor of 3 in comparison with the original HELLISH-1 structure. Therefore, the device can be operated as an ultrabright emitter with higher spectral purity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006961123975
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  • 9
    Electronic Resource
    Electronic Resource
    The numerical solution of Fredholm integral equations using product type quadrature formulas (1972)
    Springer
    BIT 12 (1972), S. 5-16 
    Details
    ISSN: 1572-9125
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract Product type quadrature formulas are applied to obtain approximate solutions of Fredholm integral equations. A convergence theorem, and several numerical examples which demonstrate the efficacy of the technique, are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01932669
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  • 10
    Electronic Resource
    Electronic Resource
    Properties of product-type quadrature formulas (1973)
    Springer
    BIT 13 (1973), S. 287-291 
    Details
    ISSN: 1572-9125
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract In this note some properties of the coefficient matrix associated with a product-interpolatory quadrature formula are determined and certain consequences of exactness of a product-type quadrature rule are deduced. For example, it is shown that the coefficient matrix has maximal rank and it is positive definite when the rule is symmetric. Conditions are stated under which a product-interpolatory rule reduces to a regular quadrature rule. A characterization of the error committed in applying a regular rule to a product of two functions is given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01951939
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