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  • 2000-2004  (7)
  • 1
    Electronic Resource
    Electronic Resource
    A simplification of the protein assay method of Ramsay et al. for the quantification of Thiobacillus ferrooxidans in the presence of ferric precipitates (2000)
    Springer
    Applied microbiology and biotechnology 53 (2000), S. 722-725 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A variation on Ramsay's method for microbial protein determination has been developed in order to quantify Thiobacillus ferrooxidans attached to ferric precipitates or in aqueous suspensions containing such precipitates. Some modifications have been introduced to provide a method that is more sensitive, simple and rapid. A linear standard curve is presented to permit a direct correlation between the protein concentration (mg/l) and the cell concentration (106 cells/ml). An application of this method has been demonstrated in the quantification of biomass immobilized on the surface of polyurethane foam particles in a packed bed reactor, several experiments having been conducted to establish the best conditions for the quantification studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530000321
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Calcium-Dependent Effects of Melatonin Inhibition of Glutamatergic Response in Rat Striatum (2001)
    Oxford, UK : Blackwell Science, Ltd
    Journal of neuroendocrinology 13 (2001), S. 0 
    Details
    ISSN: 1365-2826
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The effects of melatonin, amlodipine, diltiazem (l-type Ca2+ channel blockers) and ω-conotoxin (N-type Ca2+ channel blocker) on the glutamate-dependent excitatory response of striatal neurones to sensory-motor cortex stimulation was studied in a total of 111 neurones. Iontophoresis of melatonin produced a significant attenuation of the excitatory response in 85.2% of the neurones with a latency period of 2 min. Iontophoresis of either l- or N-type Ca2+ channel blocker also produced a significant attenuation of the excitatory response in more than 50% of the recorded neurones without significant latency. The simultaneous iontophoresis of melatonin + amlodipine or melatonin + diltiazem did not increase the attenuation produced by melatonin alone. However, the attenuation of the excitatory response was significantly higher after ejecting melatonin + ω-conotoxin than after ejecting melatonin alone. The melatonin–Ca2+ relationship was further supported by iontophoresis of the Ca2+ ionophore A-23187, which suppressed the inhibitory effect of either melatonin or Ca2+ antagonists. In addition, in synaptosomes prepared from rat striatum, melatonin produced a decrease in the Ca2+ influx measured by Fura-2AM fluorescence. Binding experiments with [3H]MK-801 in membrane preparations from rat striatum showed that melatonin did not compete with the MK-801 binding sites themselves although, in the presence of Mg2+, melatonin increased the affinity of MK-801. The results suggest that decreased Ca2+ influx is involved in the inhibitory effects of melatonin on the glutamatergic activity of rat striatum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2826.2001.00656.x
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Allergic rhinoconjunctivitis and asthma due to sensitization to Siberian hamster (2004)
    Oxford, UK : Munksgaard International Publishers
    Allergy 59 (2004), S. 0 
    Details
    ISSN: 1398-9995
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1398-9995.2004.00586.x
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of clonidine on plasma ACTH, cortisol and melatonin in children (2000)
    Copenhagen : Munksgaard
    Journal of pineal research 29 (2000), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: An interaction between melatonin and adrenocorticotropin (ACTH) seems to occur in humans and both hormones respond to beta-adrenergic stimulation. As in lower animal species, human pineal gland also contains α2-adrenergic receptors as does the hypothalamus-pituitary axis. In this study the response of the pineal gland and of the hypothalamus-pituitary-adrenal axis to α2-adrenergic stimulation was assessed. Twenty-nine children (21 males, mean age 11.2±0.6 yr and eight females, mean age 9.1±1.1 yr) from the University of Granada Hospital were studied. The children were diagnosed as having growth problems but with a normal response of growth hormone (GH) to clonidine test. Changes in plasma levels of ACTH, cortisol and melatonin were evaluated in these children after oral administration of the α2-adrenoceptor agonist clonidine (100 μg/m2) or a placebo. Plasma ACTH, cortisol and melatonin were measured before (basal) and at 30, 60 and 90 min after oral clonidine or placebo administration. Hormonal determinations were carried out by commercial radioimmunoassay kits, previously standardised in our laboratory. The results show a significant decrease in plasma ACTH, cortisol and melatonin 30 min after clonidine administration (P〈0.001), reaching lowest values at 90 min after the drug was administered. The reduction in the levels of these hormones is independent of their normal circadian decay since the control group showed a significantly different pattern of behaviour. These data support the existence of an inhibitory α2-adrenergic influence on both the pineal gland and the hypothalamus-pituitary-adrenal in children and further support the presence of α2-adrenoceptors in the human pineal gland.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1600-079X.2000.290107.x
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  • 5
    Electronic Resource
    Electronic Resource
    Melatonin-induced increased activity of the respiratory chain complexes I and IV can prevent mitochondrial damage induced by ruthenium red in vivo (2000)
    Copenhagen : Munksgaard
    Journal of pineal research 28 (2000), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Melatonin displays antioxidant and free radical scavenger properties. Due to its ability with which it enters cells, these protective effects are manifested in all subcellular compartments. Recent studies suggest a role for melatonin in mitochondrial metabolism. To study the effects of melatonin on this organelle we used ruthenium red to induce mitochondrial damage and oxidative stress. The results show that melatonin (10 mg/kg i.p.) can increase the activity of the mitochondrial respiratory complexes I and IV after its administration in vivo in a time-dependent manner; these changes correlate well with the half-life of the indole in plasma. Melatonin administration also prevented the decrease in the activity of complexes I and IV due to ruthenium red (60 μg/kg i.p.) administration. At this dose, ruthenium red did not induce lipid peroxidation but it significantly reduced the activity of the antioxidative enzyme glutathione peroxidase, an effect also counteracted by melatonin. These results suggest that melatonin modulates mitochondrial respiratory activity, an effect that may account for some of the protective properties of the indoleamine. The mitochondria-modulating role of melatonin may be of physiological significance since it seems that the indoleamine is concentrated into normal mitochondria. The data also support a pharmacological use of melatonin in drug-induced mitochondrial damage in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1600-079X.2000.280407.x
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of propranolol plus exercise on melatonin and growth hormone levels in children with growth delay (2001)
    Copenhagen : Munksgaard International Publishers
    Journal of pineal research 30 (2001), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The pineal gland in humans is under both α- and β-adrenergic control, although it seems that β1-adrenoceptors are mainly implicated in melatonin secretion. In the present study, we evaluated the role of β-adrenergic innervation on melatonin production and its relation with the production of growth hormone (GH). Thirty-four children (15 males and 19 females, mean age 10.5±0.8 years) from the University of Granada Hospital were studied. The children were included in a protocol for the evaluation of growth delay using the propranolol+exercise test. This standardized test allowed us to study simultaneously the role of an unspecific β-adrenergic blocker such as propranolol and of an adrenergic stimulus such as exercise on the pineal production of melatonin. Changes in plasma levels of melatonin and GH were determined at basal, 120 and 140 min after the test was applied. Hormonal determinations were carried out by commercial radioimmunoassay kits previously standardized in our laboratory. The results show a significant decrease in plasma melatonin levels at 120 and 140 min after the test (P〈0.05), whereas GH levels increased significantly at 140 min (P〈0.001). The decrease of melatonin levels was a consequence of the test, since in a control group, the circadian decay of melatonin was significantly less pronounced (P〈0.05). These data suggest an inverse relationship between melatonin and GH after the propranolol+exercise test, and the reduction in melatonin may be related to its depletion by exercise-induced oxidative stress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1034/j.1600-079X.2001.300202.x
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  • 7
    Electronic Resource
    Electronic Resource
    Comparative study of the kinetics of the thermal decomposition of synthetic and natural siderite samples (2000)
    Springer
    Physics and chemistry of minerals 27 (2000), S. 495-503 
    Details
    ISSN: 1432-2021
    Keywords: Key words Thermal decomposition ; Kinetics ; Siderite ; CRTA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract The mechanism of the thermal decomposition of two siderites (a pure synthetic and a natural Mg-containing sample) has been determined from comparison of the results obtained from linear heating rate (TG) and constant rate thermal analysis (CRTA) experiments in high vacuum. The thermal decomposition of the synthetic siderite takes place approximately 200 K below the decomposition temperature of the natural sample. The mechanism and the product of the thermal decomposition are different for the siderite samples. In fact, an A2 kinetic model describes the thermal decomposition of the synthetic siderite, whereas the thermal decomposition of the natural sample obeys an F1 kinetic law. Decomposition products of the synthetic siderite are iron and magnetite, those of the natural siderite are wüstite and minor magnetite.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002690000093
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