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  • Artikel: DFG Deutsche Nationallizenzen  (12)
  • 2020-2022
  • 1990-1994  (10)
  • 1980-1984
  • 1960-1964  (2)
  • 1945-1949
  • 1900-1904
  • 1870-1879
  • 2022
  • 1993  (10)
  • 1964  (2)
  • 1875
  • Free radicals
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  • Artikel: DFG Deutsche Nationallizenzen  (12)
Materialart
Erscheinungszeitraum
  • 2020-2022
  • 1990-1994  (10)
  • 1980-1984
  • 1960-1964  (2)
  • 1945-1949
    • +
Jahr
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  • 1
    Digitale Medien
    Digitale Medien
    Postischemic cell death in reperfused porcine hearts is not attenuated by the spin trap agent PBN during early reperfusion (1993)
    Springer
    Basic research in cardiology 88 (1993), S. 212-222 
    Details
    ISSN: 1435-1803
    Schlagwort(e): Free radicals ; spin trapping ; infarct size ; reperfusion injury ; ischemic cell death
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Ischemic, reperfused porcine hearts were used to investigate whether the spin trap agent PBN (N-tert-butyl-alpha-phenylnitrone) attenuates postischemic cell death by scavenging of free radicals. The left anterior descending coronary artery (LAD) was ligated distally in 16 pigs for 45 min and then reperfused for 3 h. PBN (coronary concentration approximately 1 mM) was infused into the LAD of eight pigs during the first 45 min of reperfusion. Electron spin resonance spectroscopy (ESR) was performed to identify free radical adducts in the reperfused coronary venous blood. Regional systolic shortening (SS%) was determined by sonomicrometry. Infarct size was evaluated as the percentage of infarcted (tetrazolium stain) to ischemic (dye technique) myocardium. The transmural ultrastructural degree of myocardial injury as well as myocardial ATP levels were assessed at the end of the experiment. Intracoronary treatment with PBN during early reperfusion did not attenuate myocardial damage. Infarct sizes (control group 59±19%, treated group 55±14%), transmural ultrastructural alterations, myocardial ATP concentrations (control group 1.8±0.3 μmol/mg frozen weight, treated group 1.7±0.4 μmol/mg) and regional systolic shortening at the end of the experiments (control group −1±5%, treated group −2±6% did not differ significantly. Furthermore, under various experimental conditions of spin trapping, free radical adducts could not be identified in coronary venous blood during early reperfusion. The results suggest that the spin trap agent PBN (1 mM) does not affect postischemic cell death in porcine hearts.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00794994
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  • 2
    Digitale Medien
    Digitale Medien
    Total and paramagnetic metals in human substantia nigra and its neuromelanin (1993)
    Springer
    Journal of neural transmission 5 (1993), S. 203-213 
    Details
    ISSN: 1435-1463
    Schlagwort(e): Free radicals ; trace elements ; cytotoxicity ; EPR ; Parkinson's disease ; neuromelanin ; substantia nigra
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary A number of hypotheses on the etiology of Parkinson's disease and other CNS disorders postulate a role of metal ions and/or neuromelanin. As part of an investigation of the interactions between neuromelanin and metal ions, we have studied the amount and type of metal ions in human neuromelanin in intact substantia nigra and in isolated neuromelanin using electron paramagnetic resonance (EPR), which selectively measures metal ions which are in valence states that have unpaired electrons and total reflection X-ray fluorescence (TXRF), which measures total metals. EPR also is a principal technique for studying the biophysics of melanins by analysis of its free radicals. The studies of substantia nigra with TXRF indicated the presence of substantial amounts of iron, zinc, lead, copper, maganese, and titanium at concentrations up to 4 times greater than those of non-pigmented brain tissue (basis pedunculi). The concentrations of metal ions in isolated neuromelanin were 5–260 times higher than in substantia nigra. The studies with EPR indicated that there were substantial amounts of paramagnetic metals ions, especially iron, bound to neuromelanin in intact substantia nigra, and the presence of these metal ions modified the EPR spectra of the free radicals of neuromelanin. We conclude: 1. Compared to other regions of the mid-brain, the substantia nigra contains increased amounts of many different metal ions; 2. Many of these metal ions are in paramagnetic valence states; 3. There are high concentrations of paramagnetic metal ions bound to neuromelanin. These results are consistent with the hypotheses that postulate a role of metal ions in promoting oxidative reactions in pigmented neurons.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02257675
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  • 3
    Digitale Medien
    Digitale Medien
    Ubiquinol: an endogenous antioxidant in aerobic organisms (1993)
    Springer
    Journal of molecular medicine 71 (1993), S. S60 
    Details
    ISSN: 1432-1440
    Schlagwort(e): Ubiquinone ; Free radicals ; Antioxidant
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Ubiquinone (coenzyme Q), in addition to its function as an electron and proton carrier in mitochondrial and bacterial electron transport linked to ATP synthesis, acts in its reduced form (ubiquinol) as an antioxidant, preventing the initiation and/or propagation of lipid peroxidation in biological membranes and in serum low-density lipoprotein. The antioxidant activity of ubiquinol is independent of the effect of vitamin E, which acts as a chain-breaking antioxidant inhibiting the propagation of lipid peroxidation. In addition, ubiquinol can efficiently sustain the effect of vitamin E by regenerating the vitamin from the tocopheroxyl radical, which otherwise must rely on water-soluble agents such as ascorbate (vitamin C). Ubiquinol is the only known lipid-soluble antioxidant that animal cells can synthesize de novo, and for which there exist enzymic mechanisms that can regenerate the antioxidant from its oxidized form resulting from its inhibitory effect of lipid peroxidation. These features, together with its high degree of hydrophobicity and its widespread occurrence in biological membranes and in low-density lipoprotein, suggest an important role of ubiquinol in cellular defense against oxidative damage. Degenerative diseases and aging may bc 1 manifestations of a decreased capacity to maintain adequate ubiquinol levels.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00226842
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  • 4
    Digitale Medien
    Digitale Medien
    Heart muscle ubiquinone and plasma antioxidants following cardiac transplantation (1993)
    Springer
    Journal of molecular medicine 71 (1993), S. S76 
    Details
    ISSN: 1432-1440
    Schlagwort(e): Heart transplantation ; Heart ubiquinone ; Blood and plasma ubiquinone ; Plasma α-tocopherol ; Transplant rejection ; Free radicals ; Antioxidants
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Nine patients who underwent heart transplantation (one female; average age 48 ± 11, range 19–58 years) were followed in respect to contents of right-sided heart septum, blood and plasma ubiquinone (UQ), plasma α-tocopherol (αT), and plasma free cholesterol (FC). In contrast to healthy persons, substantial inter- and intraindividual variations were observed; individually low values were seen with rejection. Heart muscle UQ in well-treated patients averaged 0.33 ± 0.08, range 0.06–0.58 μg mg−1 (0.38 ± 0.09 μmol g−1 dry weight) and was not different from healthy individuals. Plasma UQ, αT; and FC averaged 0.63 ± 0.33 μg ml−1 (P 〈 0.05 versus sedentary controls), 8.1 ± 4.0 μg ml−1 (P 〈 0.01), and 0.52 ± 0.23 mg ml−1 (P 〈 0.05). Corresponding molar values were 0.73 ± 0.37 (UQ), 2.0 ± 1.1 μmol l−1 (αT), and 1.42 ± 0.54 mmol 1−1 (FC). Blood and plasma UQ values were identical. A saturationlike relationship was found between heart and blood UQ: blood contents below 0.7 μg ml−1 (0.8 μmol l−1) corresponded to markedly lowered heart contents. In four patients in whom blood samples were taken close to a fatal complication it averaged 0.42 μg ml−1 (0.49 μmol l−t, P 〈 0.01). When low heart muscle and blood ubiquinone were present, other variables such as left ventricle cardiac output or cycle ergometer performance was markedly impaired. Plasma UQ and off covaried with a marker of the lipoidal deposit volume, plasma FC. The ratios UQ and αT over FC (N-UQ and N-αT) are alternative means for clinical evaluation. Mean N-αT was relatively more depleted than N-UQ. On an individual basis this was more pronounced for those with low N-UQ than for those with high values.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00226845
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  • 5
    Digitale Medien
    Digitale Medien
    Immunohistochemical study of copper-zinc and manganese superoxide dismutases in the lungs of human fetuses and newborn infants: Developmental profile and alterations in hyaline membrane disease and bronchopulmonary dysplasia (1993)
    Springer
    Virchows Archiv 423 (1993), S. 177-184 
    Details
    ISSN: 1432-2307
    Schlagwort(e): Fetal development ; Superoxide dismutase ; Free radicals ; Hyaline membrane disease ; Bron-chopulmonary dysplasia
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract To determine the late gestational development of copper-zinc (CnZn) and manganese (Mn) superoxide dismutases (SOD) in human lung, immunohistochemical localization was performed for each SOD. The lung samples were taken from five aborted fetuses, four fetuses in which intrauterine death occurred, one full-term neonate, two premature infants with hyaline membrane disease and one premature infant with bronchopulmonary dysplasia (BPD). Morphometry was performed, and the percent area of positive staining was computed. The bronchial epithelium was intensely stained from the early stages of gestation (i.e. 17 weeks), while the staining intensity for both CuZnSOD and MnSOD in the peripheral airways increased gradually during lung development. The mean percent area of the staining for CuZnSOD and MnSOD from 16 to 38 weeks was increased 30-fold and 8-fold, respectively, and further increases were observed postnatally. CuZnSOD staining was markedly decreased in lungs with respiratory disorders. However, proliferating type II pneumocytes were intensely stained for MnSOD in the BPD lungs, making the staining area 3-fold larger than that in the control lungs. These results clearly depict age-related increases in staining for both CuZnSOD and MnSOD and an alteration in SOD distribution associated with neonatal respiratory disorders.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01614768
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  • 6
    Digitale Medien
    Digitale Medien
    Recurrence of acute renal failure and renal hypouricaemia (1993)
    Springer
    Pediatric nephrology 7 (1993), S. 772-773 
    Details
    ISSN: 1432-198X
    Schlagwort(e): Acute renal failure ; Renal hypouricaemia ; Exercise ; Free radicals ; Uric acid ; Antioxidants
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01213352
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  • 7
    Digitale Medien
    Digitale Medien
    Ascorbate radical levels in human sera and rat plasma intoxicated with paraquat and diquat (1993)
    Springer
    Archives of toxicology 67 (1993), S. 126-130 
    Details
    ISSN: 1432-0738
    Schlagwort(e): Ascorbic acid ; Free radicals ; Electron spin resonance ; Paraquat ; Pyridinium compounds
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract To clarify the toxicological mechanism of action of paraquat and diquat, the level of ascorbate radical, an oxidized product of ascorbic acid, was examined using the electron spin resenance (ESR) method. The ascorbate radiacal level increased to twice the normal level in sera from humans acutely intoxicated with a 1∶1 mixture of paraquat and diquat, and to more than 1.5 times the normal level in rat plasma containing moderate levels of paraquat. The dosage level for rats was 0.025% paraquat dichloride in the diet. The ascorbate radical in both intoxicated human sera and rat plasma decayed much faster than that in normal samples
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01973683
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  • 8
    Digitale Medien
    Digitale Medien
    Oxygen free radicals as inducers of heat shock protein synthesis in cultured human neuroblastoma cells: Relevance to neurodegenerative disease (1993)
    Springer
    European archives of psychiatry and clinical neuroscience 242 (1993), S. 262-267 
    Details
    ISSN: 1433-8491
    Schlagwort(e): Free radicals ; Heat shock proteins ; Neurodegenerative disease
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary We studied heat shock protein (HSP) synthesis by cultured human neuroblastoma cells in response to either hyperthermia or high levels of superoxide anion (oxygen free radical). Both treatment modalities resulted in induced synthesis of the same major HSP species with an additive effect on the latter and on cell growth inhibition upon combined treatments. Exposure to superoxide anion in the presence of the free radical scavening enzymes, superoxide dismutase and catalase improved cell survival and prevented HSP induction. These findings suggest a common mechanism by which various forms of injury, such as hyperthermia, cause HSP induction, that is, via oxidative stress or increased production of oxygen free radicals. Increased expression of some HSPs has been detected in association with the pathological lesions that characterize some neurodegenerative diseases such as the neurofibrillary tangles of Alzheimer's disease. This, in turn, suggests that chronic oxidative stress may play a role in the pathogenesis of these disorders.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF02190384
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  • 9
    Digitale Medien
    Digitale Medien
    Vitamin E in extrapyramidal disorders (1993)
    Springer
    Pharmacy world & science 15 (1993), S. 146-150 
    Details
    ISSN: 1573-739X
    Schlagwort(e): Antioxidants ; Clinical trials ; Dyskinesia, drug-induced ; Free radicals ; Parkinson disease ; Pathology ; Vitamin E
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract In this article the effect of vitamin E on two extrapyramidal disorders, tardive dyskinesia and Parkinson's disease, is reviewed. After a brief description of the symptoms, the current hypotheses for the pathogenesis of these diseases are described. A summary of the clinical research that has been done to establish the effectiveness of vitamin E is given. In tardive dyskinesia four clinical trials (double-blind, placebo-controlled) showed improvement in the symptoms with vitamin E in doses of up to 1,600 IU/day. Preliminary studies concerning Parkinson's disease suggested that vitamin E (2,000 IU/day) probably cannot prevent the development of the disease. It was suggested that vitamin E is able to slow the progression of the illness. The results from a large double-blind, placebocontrolled clinical trial, however, did not show any beneficial effect of vitamin E in Parkinson's disease.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF01880556
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  • 10
    Digitale Medien
    Digitale Medien
    Rearrangements of Free Radicals, XIII[1]. Thermal and Photochemical Rearrangements of Cyclic C8H9 Radicals in Adamantane Matrix (1993)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 126 (1993), S. 1917-1927 
    Details
    ISSN: 0009-2940
    Schlagwort(e): Free radicals ; Rearrangement ; ESR spectroscopy ; Adamantane matrix ; Molecular orbital calculations ; Chemistry ; Inorganic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The ESR spectra observed after X-irradiation of bicyclo-[5.1.0]octa-2,5-diene (homotropylidene) (12) in a [D16]adamantane matrix at 210 K have been identified to be mainly due to the cyclooctatrienyl radical (8), formed by thermal ring opening of the initial bicyclo[5.1.0]octa-2,5-diene-4-yl (homotropylidenyl) radical (7). The same spectrum has also been observed in X-irradiation of bromocyclooctatriene and a mixture of bromocyclooctatriene and 7-bromobicyclo[4.2.0]cycloocta-2,4-diene in a [D16]adamantane matrix. In all cases, UV irradiation of the matrix caused an irreversible transformation of radical 8 (and probably 7) into the bicyclo[3.3.0]octa-2,6-diene-4-yl radical (17). Tricyclo[3.3.0.02,4]oct-6-en-7-yl radical (19), generated by X-irradiation of tricyclo[3.3.0.02,4]oct-2-ene (20) in adamantane, is thermally stable up to 370 K, but also undergoes a facile rearrangement to the radical 17 on UV irradiation. This process is reasonably explained to occur stepwise via radicals 7 and 8. The postulated reaction paths and the spectral assignments are supported by semiempirical (AM1, PM3), abinitio (UHF/3-21G*), and molecular mechanics (MM2ERW) calculations, which are in accord with the finding that 8 is energetically more stable than 7. The quantum mechanical calculations predict that a degenerate sigmatropic circumambulation of the cyclopropane ring in radical 7 should favorably compete with its ring opening.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/cber.19931260824
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  • 11
    Digitale Medien
    Digitale Medien
    Intramolecular Free-Radical Reactions (1964)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 3 (1964), S. 525-538 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Radical reactions ; Free radicals ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In the present article an attempt is made to summarize the steric requirements and the influence of neighboring groups which determine the course of intramolecular radical reactions. Steroids are used as substrates for these reactions, since here the spatial arrangement of the ring members and the distances between substituents are largely fixed. Furthermore, intramolecular free-radical reactions are of practical importance in steroid chemistry in connection with substitution at non-activated carbon atoms. Almost all the reactions discussed begin with the formation of an oxygen radical by oxidation of an alcohol with lead tetraacetate or by homolysis of the corresponding hypoiodite.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.196405251
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  • 12
    Digitale Medien
    Digitale Medien
    Free Radicals and Free-Radical Reactions of Monovalent and Divalent SulfurFree-radical reactions of tetra- and hexavalent sulfur are not considered in this work. For a survey of these reactions, see [16], p. 326. (1964)
    Weinheim : Wiley-Blackwell
    Angewandte Chemie International Edition in English 3 (1964), S. 602-608 
    Details
    ISSN: 0570-0833
    Schlagwort(e): Free radicals ; Radical reactions ; Sulfur ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Organic free radicals of monovalent sulfur have not been hitherto observed in solution or in melts. Steric hindrance and resonance stabilization, which are responsible for the stability of the triarylmethyl, diphenylnitrogen, and phenoxyl radicals, are apparently insufficient to stabilize the organic free radicals of monovalent sulfur in such concentrations that they can be detected by current physical methods. - It was only in 1963 that aminopolysulfur radicals (R2N—Sn—S·) were detected in solution, and arylsulfur radicals (Ar-S·) and phenylselenium radicals were isolated at ca. -180°C. - Organically bound sulfur can be stabilized in the free-radical state if association of the radicals is prevented by fixing in a crystal lattice (“cystine radical”), by repulsion between radical ions (sulfinium salts), or by freezing-in (arylsulfur radicals).
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/anie.196406021
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