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  • Springer  (175)
  • American Chemical Society (ACS)
  • 1995-1999  (175)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Determination of the intracellular targets and in vitro activity of a new class of chemical nuclease complexes derived from antibiotics of the quinolone family (1998)
    Springer
    JBIC 3 (1998), S. 188-194 
    Details
    ISSN: 1432-1327
    Keywords: Key words Quinolones ; Chemical nucleases ; DNA-interacting compounds ; SOB response
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract  Alteration of bacterial DNA structure and/or associated functions in vivo by [Cu(phen)(nal)]+, a metal complex of the type [Cu(phen)(antib)]+ (where antib is a quinolone or a fluoroquinolone), was demonstrated by the induction of a recA-lacZ fusion integrated at the amyE locus of a recombinant Bacillus subtilis strain. Using the same approach, nalidixic acid alone was shown to induce 14% of the β-galactosidase levels induced by [Cu(phen)(nal)]+; on the other hand none of the other components, i.e. copper, phenanthroline or the complex [Cu(phen)2]2+ activated significantly the recA-directed β-galactosidase activity, suggesting that the intact structure of the complex is required to reach maximum levels of induction. Results of in vitro experiments demonstrated that under reductive conditions [Cu(phen)(nal)]+ behaves as a powerful nuclease capable of degrading plasmid DNA; this activity was stronger than that of the chemical nuclease copper phenanthroline [Cu(phen)2]2+. The nuclease activity putatively occurred by a mechanism involving hydroxyl radicals since the reaction was partially inhibited by catalase. These results support the hypothesis that the mechanism of action of quinolones could be mediated by a transition metal ion such as copper.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007750050219
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  • 2
    Electronic Resource
    Electronic Resource
    Relative entropy and mixing properties of infinite dimensional diffusions (1998)
    Springer
    Probability theory and related fields 110 (1998), S. 369-395 
    Details
    ISSN: 1432-2064
    Keywords: Mathematics Subject Classification (1991): 60K35 ; 60J60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Summary. Let η be a diffusion process taking values on the infinite dimensional space T Z , where T is the circle, and with components satisfying the equations dη i =σ i (η) dW i +b i (η) dt for some coefficients σ i and b i , i∈Z. Suppose we have an initial distribution μ and a sequence of times t n →∞ such that lim n →∞μS tn =ν exists, where S t is the semi-group of the process. We prove that if σ i and b i are bounded, of finite range, have uniformly bounded second order partial derivatives, and inf i ,ησ i (η)〉0, then ν is invariant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004400050152
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  • 3
    Electronic Resource
    Electronic Resource
    An improved and reliable chili pepper (Capsicum annuum L.) plant regeneration method (1996)
    Springer
    Plant cell reports 16 (1996), S. 226-231 
    Details
    ISSN: 1432-203X
    Keywords: Capsicum annuum ; chili pepper ; organogenesis ; plant regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In this work we report a new method forin vitro chili pepper (Capsicum annuum L.) plant regeneration based on shoot formation from wounded hypocotyls. Chili pepper seeds were surface sterilized and germinated on agar (0.8%) at 25 ± 2°C in the dark. Five factors that may influence shoot regeneration were studied: age of seedlings, hypocotyl wounding site, time elapsed between wounding the hypocotyls and decapitation of seedlings, culture media and cultivars. In order to study the influence of the first three factors on shoot regeneration, the apical, middle or basal hypocotyl regions of seedlings of cv. Mulato Bajio at different stages of development (9, 15, 16, 21 and 28 d old) were wounded with a syringe needle, and the seedlings were cultured on MS semisolid medium without growth regulators at 25 ± 2°C under a 16/8 h light/dark photoperiod (daylight fluorescent lamps; 35 μmol m-2 s--1) until decapitation. The seedlings were decapitated (3 mm below the cotyledons) at different times after wounding (0, 2, 4, 10, 12 and 14 d), and each explant was evaluated for bud and shoot formation (≥ 5 mm in length) at the wounded site after 30 d of incubation. In general, seedlings at the stage of curved hypocotyl (9 d old) wounded in the apical region of hypocotyl were the best explants for shoot regeneration when inoculated on culture medium without growth regulators. Decapitation after wounding also influenced the shoot regeneration efficiency, with 10–14 d being the best period. Up to 90% shoot regeneration in cv. Mulato Bajio was obtained under these conditions. Statistically significant differences were observed for shoot formation among 21 cultivars tested. Regeneration of whole plants was achieved by rooting the shoots with indole-3-butyric acid pulses of 60 mg L−1 for 3 h and then subculturing on MS medium without growth regulators.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01890873
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  • 4
    Electronic Resource
    Electronic Resource
    An improved and reliable chili pepper (Capsicum annuum L.) plant regeneration method (1996)
    Springer
    Plant cell reports 16 (1996), S. 226-231 
    Details
    ISSN: 1432-203X
    Keywords: Key words:Capsicum annuum, chili pepper, organogenesis, plant regeneration. ; Abbreviations: BA - N6-Benzyladenine; IAA - indole-3-acetic acid; IBA - indole-3-butyric acid; MS - Murashige and Skoog (1962) medium; TDZ - thidiazuron.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. In this work we report a new method for in vitro chili pepper (Capsicum annuum L.) plant regeneration based on shoot formation from wounded hypocotyls. Chili pepper seeds were surface sterilized and germinated on agar (0.8%) at 25 ± 2°C in the dark. Five factors that may influence shoot regeneration were studied: age of seedlings, hypocotyl wounding side, time elapsed between wounding the hypocotyls and decapitation of seedlings, culture media and cultivars. In order to study the influence of the first three factors on shoot regeneration, the apical, middle or basal hypocotyl regions of seedlings of cv. Mulato Bajío at different stages of development (9, 15, 16, 21 and 28 d old) were wounded with a syringe needle, and the seedlings were cultured on MS semisolid medium without growth regulators at 25 ± 2°C under a 16/8 h light/dark photoperiod (daylight fluorescent lamps; 35 μmol m–2 s–1) until decapitation. The seedlings were decapitated (3 mm below the cotyledons) at different times after wounding (0, 2, 4, 10, 12 and 14 d), and each explant was evaluated for bud and shoot formation (≥5 mm in length) at the wounded site after 30 d of incubation. In general, seedlings at the stage of curved hypocytyl (9 d old) wounded in the apical region of hypocotyl were the best explants for shoot regeneration when inoculated on culture medium without growth regulators. Decapitation after wounding also influenced the shoot regeneration efficiency, with 10–14 d being the best period. Up to 90% shoot regeneration in cv. Mulato Bajío was obtained under these conditions. Statistically significant differences were observed for shoot formation among 21 cultivars tested. Regeneration of whole plants was achieved by rooting the shoots with indole-3-butyric acid pulses of 60 mg L–1 for 3 h and then subculturing on MS medium without growth regulators.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002990050212
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  • 5
    Electronic Resource
    Electronic Resource
    Large-scale cultivation of Solanum chrysotrichum cells: Production of the antifungal saponin SC-1 in 10-l airlift bioreactors (1997)
    Springer
    Plant cell reports 16 (1997), S. 653-656 
    Details
    ISSN: 1432-203X
    Keywords: Key wordsSolanum chrysotrichum ; Cell suspension culture ; Spirostanol saponins ; Antimycotic ; Large-scale culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cells of two different cell lines: ccvx (cotyledon derived) and ccvz (hypocotyl derived) of Solanum chrysotrichum were cultivated in 10-l airlift bioreactors for the production of the human antimycotic compound SC-1. When using 3 g l–1 dry weight inoculum in a batch culture, higher levels of biomass were achieved with the ccvx cell line (14.6 g l–1) than with ccvz (7.7 g l–1), resulting in 23 and 12 mg g–1 of SC-1 after 17 days in culture for ccvx and ccvz, respectively. The maximum productivity of SC-1 in bioreactors was 0.025 g l–1 day–1 after 9 days in culture. When using a draw-fill mode, the productivity increased by 60% to a value of 0.041 g l–1 day–1, 4 days after 50% of the cell suspension was removed and replaced with fresh medium. This latter bioreactor system is a feasible alternative for the production of the antimycotic metabolite of S. chrysotrichum on a large scale.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002990050296
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  • 6
    Electronic Resource
    Electronic Resource
    Algebras of singular integral operators generated by three orthogonal projections (1996)
    Springer
    Integral equations and operator theory 25 (1996), S. 277-288 
    Details
    ISSN: 1420-8989
    Keywords: 47B35 ; 47D25
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract The structure of theC *-algebra with identity generated by two orthogonal projections is well understood. All irreducible representations of this algebra are either two-dimensional or one-dimensional. The situation becomes unpredictable in the case of theC *-algebra generated by three orthogonal projections. Even in the more specific case when two of the projections commute, the algebra under consideration may have infinite dimensional irreducible representations. In this paper we produce three concrete realizations of the algebra generated by three orthogonal projections in that specific case. It turns out that these algebras have quite different structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01262295
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  • 7
    Electronic Resource
    Electronic Resource
    Overexpression of copper-zinc superoxide dismutase in trisomy 21 (1996)
    Springer
    Cellular and molecular life sciences 52 (1996), S. 871-873 
    Details
    ISSN: 1420-9071
    Keywords: Critical region ; CuZnSOD ; Down's syndrome ; gene dosage ; trisomy 21
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Down's syndrome (DS), the most frequent of congenital birth defects, results from the trisomy of chromosome 21 in all cells of affected patients. This disease is characterized by developmental anomalies, mental retardation and features of rapid aging, particularly in the brain, where the occurrence of Alzheimer's disease is observed in trisomy 21 patients over the age of 35. Copper-zinc superoxide dismutase (CuZnSOD) is one of the proteins encoded by chromosome 21 (21q22.1). As a consequence of gene dosage excess, CuZnSOD activity is increased by 50% in all DS tissues. This work reports the SOD activity of a population of DS patients with complete trisomy 21, partial trisomy 21, translocations and mosaicism, in order to confirm the gene dosage effect of SOD on the clinical features of DS, and to help to establish which is the critical region of chromosome 21 in DS. CuZnSOD was measured in red blood cells using the Minami and Yoshikawa method. In the population with complete trisomy 21, SOD activity was increased by 42%; in the population with partial trisomy 21, translocations and mosaicism, SOD activity was normal. In the population diagnosed as DS, but not karyotyped, SOD activity was increased by 28%. No differences between sexes or among ages were found. We conclude that the 21q22.1 segment is not the critical region responsible for DS, as we have found normal SOD activity in patients with the clinical features of DS.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01938872
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  • 8
    Electronic Resource
    Electronic Resource
    A straightforward estimation of the maximum sunspot number for cycle 23 (1999)
    Springer
    Annales geophysicae 17 (1999), S. 639-641 
    Details
    ISSN: 0992-7689
    Keywords: Solar physics ; astrophysics and astronomy (magnetic fields; general)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Using the annual number of geomagnetically quiet days (aa 〈 20 γ) for the year after the solar minimum, this precursor method predicts that the maximum sunspot number for cycle 23 will be 140 + 32, indicating that cycle 23 will be similar to cycles 21 and 22.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00585-999-0639-7
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  • 9
    Electronic Resource
    Electronic Resource
    Straight Line Arrangements in the Real Projective Plane (1998)
    Springer
    Discrete & computational geometry 20 (1998), S. 155-161 
    Details
    ISSN: 1432-0444
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract. Let ${\cal A}$ be an arrangement of n pseudolines in the real projective plane and let $p_3({\cal A})$ be the number of triangles of ${\cal A}$ . Grünbaum has proposed the following question. Are there infinitely many simple arrangements of straight lines with $p_3({{\cal A}})={1/3}n(n-1)$ ? In this paper we answer this question affirmatively. 〈lsiheader〉 〈onlinepub〉7 August, 1998 〈editor〉Editors-in-Chief: &lsilt;a href=../edboard.html#chiefs&lsigt;Jacob E. Goodman, Richard Pollack&lsilt;/a&lsigt; 〈pdfname〉20n2p155.pdf 〈pdfexist〉yes 〈htmlexist〉no 〈htmlfexist〉no 〈texexist〉no 〈sectionname〉 〈/lsiheader〉
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00009373
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  • 10
    Electronic Resource
    Electronic Resource
    Spatial Graphs and Oriented Matroids: the Trefoil (1999)
    Springer
    Discrete & computational geometry 22 (1999), S. 149-158 
    Details
    ISSN: 1432-0444
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract. Let m=m(K) be the smallest positive integer such that every linear spatial representation of the complete graph with n vertices, n ≥ m , contains either the knot K or its mirror . In this paper we show that m(Trefoil)=7 . The proof uses the theory of oriented matroids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00009446
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