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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    The journal of membrane biology 156 (1997), S. 231 -239 
    ISSN: 1432-1424
    Keywords: Key words:45Ca2+ efflux — Caffeine — Ruthenium red — Heparin — Endoplasmic reticulum — Thapsigargin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract. We have measured ryanodine (caffeine)-sensitive 45Ca2+ release from isolated microsomal vesicles of endoplasmic reticulum prepared from rat parotid acinar cells. After a steady state of ATP-dependent 45Ca2+ uptake, the addition of caffeine (40 mm), ryanodine (10∼500 μm) or an NAD+ metabolite, cyclic ADP-ribose (cADPR, 4 μm) released about 10% of the 45Ca2+ that had been taken up. The 45Ca2+ release was not inhibited by heparin, an antagonist of IP3 receptor. The effects of caffeine, ryanodine and cADPR on 45Ca2+ release were also tested in the presence of thapsigargin (TG), an inhibitor of microsomal Ca2+-ATPase. When caffeine (10∼40 mm), ryanodine (10 μm) or cADPR (1∼10 μm) was added in the medium with 100 nm TG, a significant 45Ca2+ release was seen, while higher concentrations of ryanodine (〉100 μm) did not cause any 45Ca2+ release in the presence of TG. The initial rate of caffeine (40 mm)-induced 45Ca2+ release was increased by a pretreatment with 10 μm ryanodine, whereas the caffeine-induced 45Ca2+ release was strongly inhibited by the presence of a higher concentration (500 μm) of ryanodine. cADPR-induced 45Ca2+ release was also inhibited by 500 μm ryanodine. Caffeine (40 mm)- or cADPR (4 μm)-induced 45Ca2+ release was abolished by a presence of ruthenium red (50∼100 μm). The presence of a low concentration (0.5 μm) of cADPR shifted the dose-response curve of caffeine-induced 45Ca2+ release to the left. These results indicate the presence of a ryanodine sensitive Ca2+ release mechanism in the endoplasmic reticulum of rat parotid acinar cells that is distinct from the IP3-sensitive Ca2+ channel and is activated by caffeine, cADPR and a low concentration (10 μm) of ryanodine, but is inhibited by higher concentrations (〉100 μm) of ryanodine and ruthenium red. The properties of the ryanodine-sensitive mechanism are similar to that of the ryanodine receptor as described in muscle cells.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1424
    Keywords: Thapsigargin ; Vanadate ; Ca2+ pump ; Ca2+ ATPase ; SERCA ; Endoplasmic reticulum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract We have examined the effect of the Ca2+ (Mg2+)-ATPase inhibitors thapsigargin (TG) and vanadate on ATP-dependent 45Ca2+ uptake into IP3-sensitive Ca2+ pools in isolated microsomes from rat pancreatic acinar cells. The inhibitory effect of TG was biphasic. About 40–50% of total Ca2+ uptake was inhibited by TG up to 10 nm (apparent Ki≈4.2 nm, Ca2+ pool I). An additional increase of inhibition up to 85–90% of total Ca2+ uptake could be achieved at 15 to 20 nm of TG (apparent Ki≈12.1 nm, Ca2+ pool II). The rest was due to TG-insensitive contaminating plasma membranes and could be inhibited by vanadate (apparent Ki≈10 μm). In the absence of TG, increasing concentrations of vanadate also showed two phases of inhibition of microsomal Ca2+ uptake. About 30–40% of total Ca2+ uptake was inhibited by 100 μm of vanadate (apparent Ki≈18 μm, Ca2+ pool II). The remaining 60–70% could be inhibited either by vanadate at concentrations up to 1 mm (apparent Ki≈300 μm) or by TG up to 10 nm (Ca2+ pool I). The amount of IP3-induced Ca2+ release was constant at ≈25% over a wide range of Ca2+ filling. About 10–20% remained unreleasable by IP3. Reduction of IP3 releasable Ca2+ in the presence of inhibitors showed similar dose-response curves as Ca2+ uptake (apparent Ki≈ 3.0 nm for IP3-induced Ca2+ release as compared to ≈4.2 nm for Ca2+ uptake at TG up to 10 nm) indicating that the highly TG-sensitive Ca2+ pump fills the IP3-sensitive Ca2+ pool I. At TG concentrations 〉10 nm which blocked Ca2+ pool II the apparent Ki values were ≈11.3 and ≈12.1 nm, respectively. For inhibition by vanadate up to 100 μm the apparent Ki values were ≈18 μm for Ca2+ uptake and ≈7 μm for Ca2+ release (Ca2+ pool II). At vanadate concentrations up to 1 mm the apparent Ki values were ≈300 and ≈200 μm, respectively (Ca2+ pool I). Both Ca2+ pools I and II also showed different sensitivities to IP3. Dose-response curves for IP3 in the absence of inhibitors (control) showed an apparent Km value for IP3 at 0.6 μm. In the presence of TG (inhibition of Ca2+ pool I) the curve was shifted to the left with an apparent Km for IP3 at 0.08 μm. In the presence of vanadate (inhibition of Ca2+ pool II), the apparent Km for IP3 was 2.1 μm. These data allow the conclusion that there are at least three different Ca2+ uptake mechanisms present in pancreatic acinar cells: TG- and IP3 insensitive but highly vanadate-sensitive Ca2+ uptake occurs into membrane vesicles derived from plasma membranes. Two Ca2+ pools with different TG-, vanadate- and IP3-sensitivities are most likely located in the endoplasmic reticulum at different cell sites, which could have functional implications for hormonal stimulation of pancreatic acinar cells.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0942-0940
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0942-0940
    Keywords: Intracerebral haemorrhage ; spontaneous cerebral haemorrhage ; amyloid angiopathy ; surgery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Nineteen patients with massive lobar haemorrhage without angiographic lesions received direct or stereotactic surgery, and biopsy specimens were examined histologically. Ten patients (53%) were found to have vessels positive for Congo-red staining, and demonstrating amyloid angiopathy. In the patients with amyloid angiopathy, CT scan and surgical findings were investigated. Subarachnoid haemorrhage (9/10), irregularly shaped haematoma (9/10) and fluid-blood density level in the haematoma cavity (7/10) were frequently found on CT scan. The characteristic surgical findings in patients treated by direct surgery were subarachnoid haemorrhage adjacent to intracerebral haematoma (8/8) and the existence of a tangle of vessels in the haematoma cavity (4/8). Evacuation of haematomas was relatively easy, and difficulty of haemostasis was not encountered during surgery.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1744-313X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Selective IgM deficiency is commonly found in Bloom's syndrome (BS). We reported that membrane-bound μ (μ m) mRNA was well transcribed but secreted μ (μ s) mRNA was not, although there was no mutation or deletion in the sequence including the (is C-terminal coding sequence in the patients with BS. Furthermore, we have shown previously, preferential damage to IgM production by ultraviolet (UV) irradiation of the cells of the patient. In the study described here, mutation in the sequence which is upstream of the 5’ end of the μ s C-terminal coding sequence was induced by UV irradiation in the lymphoblastoid cell line (LCL) of BS patient. These results suggest that abnormal repair of DNA damage is present in this LCL, and that preferential damage to IgM production by UV irradiation in this LCL may be due to the abnormal repair of DNA damage.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Alimentary pharmacology & therapeutics 9 (1995), S. 0 
    ISSN: 1365-2036
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Aim: To assess the effects of FK506, a newly developed immunosuppressant, on experimental colitis in rats. Methods: Experimental colitis was induced by a single colonic instillation of hapten 2,4,6-trinitrobenzene sulphonic acid (TNB) in anaesthetized rats. Rats received 30 mg TNB dissolved in 0.25 mL of 50% ethanol, and were sacrificed on day 5 following 4 days dosing with FK506 (0.25, 0.5, 1.0, 2.0 mg/kg, s.c.) or vehicle. Mucosal prostanoid concentrations were determined using high performance liquid chromotography. Tissue myeloperoxidase activities were measured. The effects of FK506 on superoxide radical formation by neutrophils in both rats and humans were also estimated in vitro.Results: Administration of FK506 significantly reduced the colonic damage in a dose-dependent manner. Activities of myeloperoxidase and concentrations of 6-keto-prostaglandin Fl1α (6-keto-PGF1α, PGF2α and PGE2 in colonic tissue increased significantly following induction of experimental colitis, however, FK506 did not affect these changes. FK506 reduced stimulant-induced superoxide radical formation by neutrophils in rats and humans. Conclusion: FK506 decreased superoxide radical generation by neutrophils, which might contribute to the lessening of colonic damage in this model.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 47 (1996), S. 1105-1120 
    ISSN: 1572-8943
    Keywords: activation energy ; DTA-TG ; EGA ; hydrolysis ; reaction calorimetry ; thermal decomposition ; thermal endurance ; thermal life ; thermo-oxidative deterioration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Thermal analysis techniques, such as thermogravimetry, differential thermal analysis and evolved gas analysis, have been applied to thermal endurance evaluation of electrical insulating materials of high polymers, which are used for a long time at a relatively high operating temperature. Various attempts have been made to estimate the life time of the materials at the operating temperature by thermal analysis and a calorimetric method. These are critically described in this review paper.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 54 (1998), S. 521-534 
    ISSN: 1572-8943
    Keywords: heat capacity measurement ; heat flux DSC ; steady state ; TMDSC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The steady state of temperature modulated heat flux DSC, in which the sample temperature is controlled at a fixed frequency, a fixed amplitude and a constant underlying heating rate, is theoretically investigated for complex heat capacity of the sample, taking accounts of heat capacities of heat paths, heat loss to the environment and mutual heat exchange between the sample and the reference material. Rigorous and general solutions for the temperature difference oscillation are obtained in relation to the sample temperature as a reference oscillation. The results are quite different from those obtained in functions of the heat source temperature as a reference oscillation. From these solutions, application of the technique to heat capacity measurements is discussed.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 56 (1999), S. 691-697 
    ISSN: 1572-8943
    Keywords: heat capacity measurement ; power compensation DSC ; steady state ; temperature modulated DSC ; temperature modulated power compensation DSC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The steady state of temperature modulated power compensation DSC has been theoretically investigated for measurements of complex heat capacity, taking accounts of heat capacities of heat paths, heat loss to the environment, and mutual heat exchange between the sample and the reference material. Thermal contact between the sample cell and the cell holder is also taken into accounts. Rigorous and general solutions are obtained. From these solutions application of the technique to heat capacity measurements is discussed.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Mathematische Zeitschrift 231 (1999), S. 479-487 
    ISSN: 0025-5874
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
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