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  • 1
    Electronic Resource
    Electronic Resource
    Glycogen concentration in human skeletal muscle: effect of prolonged insulin and glucose infusion (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Scandinavian journal of medicine & science in sports 9 (1999), S. 0 
    Details
    ISSN: 1600-0838
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Sports Science
    Notes: To study the upper limit of glycogen storage in human muscle, two healthy male subjects were infused with glucose and insulin for 8 h reaching plasma concentrations of about 21 mM glucose and approximately 2000 μU/ml insulin. Prior to the infusion subjects performed for 1 h one-legged knee-extensor exercise at 75% of their maximum one-legged work capacity in order to lower muscle glycogen stores in one leg. During the 8-h hyperglycemic clamp procedure, glycogen concentrations increased and levelled off at 2- and 5-fold above the pre-infusion levels in the resting and the working leg, respectively. However, the absolute glycogen levels reached in both legs were quite similar, close to 4 g per 100 g wet muscle (about 1000 μmol/g d.w.), independent of prior exercise. Previous studies have shown that glycogen levels, after a bout of glycogen-depleting exercise and subsequent ingestion of a carbohydrate-rich diet for 3 days, can be increased to values around 3–4 g per 100 g wet muscle. It appears that the maximal attainable glycogen concentration in human muscle seems to be close to 4 g per 100 g wet muscle. This glycogen level can thus be reached either by a prolonged infusion of supra-physiological concentrations of glucose and insulin or by glycogen-depleting exercise followed by ingestion of a carbohydrate-rich diet.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-0838.1999.tb00235.x
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  • 2
    Electronic Resource
    Electronic Resource
    Metabolism of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in isolated rat lung and liver (1998)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 357 (1998), S. 336-343 
    Details
    ISSN: 1432-1912
    Keywords: Key words NNK ; Elimination kinetics ; Metabolism ; Perfusion ; Lung ; Liver ; Rat ; N-oxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The tobacco specific nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is a strong lung carcinogen in all species tested. To elicit its tumorigenic effects NNK requires metabolic activation which is supposed to take place via α-hydroxylation, whereas N-oxidation is suggested to be a detoxification pathway. The differences in the organ specific metabolism of NNK may be crucial for the organotropy in NNK-induced carcinogenesis. Therefore, metabolism of NNK was investigated in the target organ lung and in liver of Fischer 344 (F344) rats using the model of isolated perfused organs. High activity to metabolize 35 nM [5-3H]NNK was observed in both perfused organs. NNK was eliminated by liver substantially faster (clearance 6.9 ± 1.6 ml/min, half-life 14.6 ± 1.2 min) than by lung (clearance 2.1 ± 0.5 ml/min, half-life 47.9 ± 7.4 min). When the clearance is calculated for a gram of organ or for metabolically active cell forms, the risk with respect to carcinogenic mechanisms was higher in lung than in liver. The metabolism of NNK in liver yielded the two products of NNK α-hydroxylation, the 4-oxo-4-(3-pyridyl)-butyric acid (keto acid) and 4-hydroxy-4-(3-pyridyl)-butyric acid (hydroxy acid). In lung, the major metabolite of NNK was 4-(methylnitrosamino)-1-(3-pyridyl-N-oxide)-1-butanone (NNK-N-oxide). Substantial amounts of metabolites formed from methyl hydroxylation of NNK, which is one of the two possible pathways of α-hydroxylation, were detected in lung but not in liver perfusion. Formation of these metabolites (4-oxo-4-(3-pyridyl)-butanol (keto alcohol), and 4-hydroxy-4-(3-pyridyl)-butanol (diol) can give rise to pyridyloxobutylating of DNA. When isolated rat livers were perfused with 150 μM NNK, equal to a dosage which is sufficient to induce liver tumors in rat, glucuronidation of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) was increased when compared to the concentration of 35 nM NNK. Nevertheless, the main part of NNK was also transformed via α-hydroxylation for this high concentration of NNK.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00005176
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of nicotine or cotinine on metabolism of 4-methylnitrosamino-1-(3-pyridyl)-1-butanone (NNK) in isolated rat lung and liver (1998)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 357 (1998), S. 344-350 
    Details
    ISSN: 1432-1912
    Keywords: Key words NNK ; Nicotine ; Cotinine ; Starvation ; Metabolism ; Lung ; Liver ; Perfusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The scope of the present study was to investigate whether nicotine or cotinine will affect the metabolism of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in isolated perfused rat lungs and livers and to study the effect of starvation on pulmonary metabolism of NNK. NNK metabolism was investigated in isolated perfused liver and lung of male F344 rats perfused with 35 nM [5-3H]NNK in presence of a 1400-fold excess of the main tobacco alkaloid nicotine and its metabolite cotinine. In perfused rat livers, nicotine and cotinine inhibited NNK elimination and metabolism and led to a substantial increase of elimination half-life from 14.6 min in controls to 25.5 min after nicotine and 36.6 min after cotinine co-administration, respectively. In parallel, the pattern of NNK metabolites was changed by nicotine and cotinine. The pathway of α-hydroxylation representing the metabolic activation of NNK was decreased to 77% and 85% of control values, whereas N-oxidation of NNK and glucuronidation of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) was increased 2.6- and 1.2-fold in presence of nicotine and cotinine, respectively. When isolated rat lungs were perfused with 35 nM NNK for 3 h neither the elimination nor the pattern of metabolites were substantially affected due to co-administration of 50 μM nicotine or cotinine. Cytochrome P450 2E1 is known to participate in the activation of NNK and can be induced by starvation. However, isolated rat lungs from male Sprague Dawley rats perfused with [1-14C]NNK at about 2 μM for 3 h, revealed only small differences in pulmonary elimination and pattern of NNK metabolites between fed and starved animals. These results suggest that nicotine and its main metabolite cotinine inhibit the metabolic activation of NNK predominantly in the liver whereas activation in lung, a main target organ of NNK induced carcinogenesis, remained almost unaffected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00005177
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  • 4
    Electronic Resource
    Electronic Resource
    Inhibition of muscle glycogen synthase activity and non-oxidative glucose disposal during hypoglycaemia in normal man (1996)
    Springer
    Diabetologia 39 (1996), S. 226-234 
    Details
    ISSN: 1432-0428
    Keywords: Hypoglycaemia ; counter-regulation ; glucose disposal ; muscle glycogen synthase activity ; glucose mass effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The purpose of the present study was to evaluate the role of muscle glycogen synthase activity in the reduction of glucose uptake during hypoglycaemia. Six healthy young men were examined twice; during 120 min of hyperinsulinaemic (1.5 mU · kg−1 · min−1) euglycaemia followed by: 1) 240 min of graded hypoglycaemia (plasma glucose nadir 2.8 mmol/l) or 2) 240 min of euglycaemia. At 350–360 min a muscle biopsy was taken and indirect calorimetry was performed at 210–240 and 330–350 min. Hypoglycaemia was associated with markedly increased levels of adrenaline, growth hormone and glucagon and also with less hyperinsulinaemia. During hypoglycaemia the fractional velocity for glycogen synthase was markedly reduced; from 29.8±2.3 to 6.4±0.9%, p〈0.05. Total glucose disposal was decreased during hypoglycaemia (5.58±0.55 vs 11.01±0.75 mg · kg−1 · min−1 (euglycaemia); p〈0.05); this was primarily due to a reduction of non-oxidative glucose disposal (2.43±0.41 vs 7.15±0.7 mg · kg−1 · min−1 (euglycaemia); p〈0.05), whereas oxidative glucose disposal was only suppressed to a minor degree. In conclusion hypoglycaemia virtually abolishes the effect of insulin on muscle glycogen synthase activity. This is in keeping with the finding of a marked reduction of non-oxidative glucose metabolism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00403967
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  • 5
    Electronic Resource
    Electronic Resource
    Separation of the reaction products of cyanazine and terbuthylazine nitrosation by thin-layer chromatography (1998)
    Springer
    Fresenius' journal of analytical chemistry 360 (1998), S. 679-682 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract N-Nitroso-triazine herbicide species were synthesized as reference standards and their reaction products were separated by TLC. The method was established for analytical as well as for preparative amounts to achieve a sufficient separation between the educts, the byproducts and the N-nitrosated moieties. Separation of the reaction mixture was performed by two-dimensional TLC, using different mobile phases for each dimension. In the second dimension two developments were executed using the same solvent mixture. To examine the quality of performance, the separation zones were scrapped off, extracted and analyzed in the HPLC-diode array detection (DAD) mode in comparison with standards of the educts and the products of their N-nitrosation. This method minimizes the contact with the resulting N-nitroso compounds. At present nothing is known about the toxicological relevance or risk assessment on human health of N-nitrosocyanazine or N-nitrosoterbuthylazine species. Therefore the practical handling of these putative mutagenic and carcinogenic substances should be seen under the aspect of precaution and prevention of contamination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160050780
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  • 6
    Electronic Resource
    Electronic Resource
    Gas-sensor properties of SnO2 films implanted with gold and iron ions (1997)
    Springer
    Journal of materials science 8 (1997), S. 301-306 
    Details
    ISSN: 1573-482X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract SnO2 gas-sensor films were modified by implantation of gold and iron ions. The change in electrical resistivity of the films caused by inflammable gases, H2, CO, CH4 and C2H5OH, was measured in the temperature range 100–500°C, and compared to non-implanted films. The morphological changes caused by gold and iron ion implantation were also investigated by atomic force microscopy. After ion implantation and annealing at 600°C, the sensitivity to H2 and CO gas was found to increase, and the dynamic range of the sensitivity to ethanol was improved. The sensitivity to CH4 was low before and after ion implantation. Fe2O3 (3%SnO2) film was also modified by gold ion implantation for comparison.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018535322380
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  • 7
    Electronic Resource
    Electronic Resource
    Growth of anchorage-dependent mammalian cells on microstructures and microperforated silicon membranes (1996)
    Springer
    Journal of materials science 7 (1996), S. 85-97 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Anchorage-dependent cells (mouse fibroblasts L929 and 3T3) were cultivated on microstructures made by semiconductor technology. Both cell lines showed normal growth on silicon surfaces covered with microelectrode arrays as well as on microperforated silicon membranes with square pores made by anisotropic etching (5, 10 or 20 μm edge length at the top and 1.2, 6.2 or 16.2 μm at the bottom). The cells spread over the 5 and 10 μm pores, but mostly failed to cover the 20 μm ones. They were able to cross the silicon membrane through the pores and to grow and spread on the under side of the membrane. Small pores (about 1 μm2) impeded but did not prevent cells crossing the membrane. Medium and large pores were freely crossed. Negative dielectrophoresis was used to achieve accurate positioning of cells above pores or to repel them from the chip surface (a.c., square wave, 2.5 V peak-to-peak, 5 MHz). The results are discussed with respect to their microtool applications for single-cell technologies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00058719
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  • 8
    Electronic Resource
    Electronic Resource
    Salivary gland scintigraphy using technetium-99m-pertechnetate after autotransplantation of the submandibular salivary gland in the correction of dry eye (1998)
    Springer
    European journal of nuclear medicine 25 (1998), S. 128-131 
    Details
    ISSN: 1619-7089
    Keywords: Key words: Salivary gland scintigraphy ; Submandibular gland transplantation ; Dry eye syndrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The aim of the study was to determine whether salivary gland scintigraphy using technetium-99m pertechnetate is suitable for checking the vitality and function after autotransplantation of the submandibular salivary gland in patients with dry eye syndrome. To this end, 56 scintigraphic studies in 20 patients have so far been performed. In addition, these scans were evaluated by a region of interest (ROI) technique in order to examine tracer uptake in the early and late stages after surgery. We have been able to prove that in this special respect, too, the salivary gland scintigraphy is suitable for assessing reliably the vitality and function of the transplanted gland. The secretion into the eye and thus the patency of the efferent duct can also be displayed. This proved to be particularly valuable in those cases in which at first no secretion could be seen in the clinical examination. In patients with uncertain excretory function, we were able to distinguish between non-vitality and lack of patency of the secretory duct. Using ROI evaluation, no significant decrease in the salivary function has been detected in long-term follow-up, now extending to 1 year after surgery.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002590050204
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  • 9
    Electronic Resource
    Electronic Resource
    Pyrimethamine alone as prophylaxis for cerebral toxoplasmosis in patients with advanced HIV infection (1996)
    Springer
    Infection 24 (1996), S. 324-327 
    Details
    ISSN: 1439-0973
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Bei 56 Patienten mit fortgeschrittener HIV-Infektion wurde eine Prophylaxe der cerebralen Toxoplasmose mit Pyrimethamin als Monotherapie in einer Dosierung von 50 mg täglich durchgeführt. 38 dieser Patienten wiesen ein hohes Risiko für die Entwicklung einer Toxoplasma-Encephalitis auf (CD4+-Zellen ≤200/µl und Nachweis von IgG-Antikörpern gegenToxoplasma gondii). Die gesamte Behandlungsdauer betrug 697 Monate (im Mittel 12,5±12,1). Während der Prophylaxe entwickelte lediglich ein Patient eine cerebrale Toxoplasmose, vier Patienten brachen die Behandlung wegen Nebenwirkungen ab. Steady-state-Pyrimethamin-Plasmakonzentrationen wurden durch Gaschromatographie bestimmt. Der mittlere Plasmaspiegel betrug 1.887±1.161 ng/ml, während einer Leberenzym-induzierenden Komedikation wurden signifikant (p=0,0001) verminderte (1.488±884 ng/ml vs. 1.978±1.196 ng/ml ohne Komedikation) Plasmakonzentrationen gemessen. Alle Patienten erhielten additiv 7,5 mg Folinsäure pro Tag. Die gemessenen Serum-Folsäurespiegel schwankten zwischen 5,7 und 105 (43,7±29,2) nmol/l, schwerwiegende hämatologische Nebenwirkungen traten hierunter nicht auf.
    Notes: Summary Prophylaxis for toxoplasma encephalitis was performed with pyrimethamine alone (50 mg daily) in 56 patients with advanced HIV infection. Thirty-eight patients were at high risk for toxoplasma encephalitis (CD4+ counts ≤200/ µl, and presence of serum IgG antibodies toToxoplasma gondii). The overall treatment period was 697 months (mean 12.5±12.1). During prophylaxis, only one patient developed toxoplasma encephalitis, four patients discontinued treatment due to adverse reactions. Steady state pyrimethamine plasma concentrations were measured by gas chromatography. Mean plasma level was 1,887±1,161 ng/ml, during liver enzyme-inducing comedication plasma levels were significantly (p=0.0001) reduced (1,488±884 ng/ml versus 1,978±1,196 ng/ml without comedication). All patients received a folinic acid supplement of 7.5 mg daily. Serum folate levels ranged from 5.7–105 (43.7±29.2) nmol/l; severe hematological side effects did not occur.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01743370
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  • 10
    Electronic Resource
    Electronic Resource
    Investigation of Fe-Mg-Alloys Produced by Ion Implantation (1998)
    Springer
    Hyperfine interactions 112 (1998), S. 165-168 
    Details
    ISSN: 1572-9540
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Iron and magnesium are insoluble elements with each other and there is no phase diagram. However, it is possible to produce artificial alloys by ion implantation, in this study by iron implantation into magnesium. Samples are investigated by conversion electron Moessbauer spectroscopy, Auger electron spectroscopy and x-ray diffraction. While at low doses gaussian shaped iron profiles and paramagnetic doublets as Mössbauer spectra are obtained, the iron concentration reaches at the highest dose 90 at.-% in maximum and the Mössbauer spectrum shows a dominant ferromagnetic fraction. The x-ray diffraction pattern let conclude that a dilated α-iron lattice is formed. Microhardness of all samples is clearly increased due to the implantation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1011021618496
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