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  • Articles  (34)
  • Springer  (33)
  • Cold Spring Harbor Laboratory Press  (1)
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  • Articles  (34)
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  • 1
    ISSN: 1573-904X
    Keywords: isoindolo[l,2-b]quinazolines ; cytotoxicity ; DNA topoisomerase ; colon adenocarcinoma 38 ; structure–activity relationship
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A number of isoindolo[l ,2-b]quinazolines and some benzo[4,5]isoquinolino[l,2-b]quinazolines as structural modification analogues of the antitumor compound batracylin were synthesized and evaluated against HL-60 cell growth and in topoisomerase II-mediated DNA cleavage assays. Of the compounds studied, 10,12-dihydro-7,8-methy lenedioxyisoindolo[ 1,2-b] quinazolin-12(10H)-one (1d), 2-amino-10,12-dihydroisoindolo[l ,2-b]quinazolin- 12(10H)-one (1p), and 2-amino-7,8-methylenedioxy-10,12-dihydroisoindolo[l ,2-b]quinazolin-12(10H)-one (1ab) exhibited good inhibitory activities against HL-60 cell lines as well as induction of topo II-mediated DNA cleavage activities.
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  • 2
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Carbohydrates ; Enzymic hydrolysate ; Waste paper
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Waste paper was pretreated with 5M sulfuric acid at 28°C to give a gel-like solution which was then hydrolyzed with cellulase, purified fromTrichoderma viride, to form carbohydrates. The determination of the carbohydrates was accomplished using an aminopropylbonded silica HPLC column and an RI detector. The detection limits were 20 ppm; xylose, glucose, and cellobiose were the major components. Salts from the buffer solution may affect the activity of cellulase. The analysis of carbohydrates can be performed under acid conditions. HPLC analysis of carbohydrates from enzymatic hydrolysis is reliable and successful.
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  • 3
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ligand exchange ; Amino acid enantiomers ; DL-aspartic acid ; Pseudomonas dacunhae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation of the D and L enantiomers of eighteen essential α amino acids has been investigated by ligand-exchange chromatography (LEC). The effect of column temperature on the retention times and resolution of individual amino acid enantiomers has been studied by varying the temperature from 25 to 50 °C for a mobile phase containing Cu2+ ions. By use of a temperature of 50 °C and Zn2+ in the mobile phase, eight of the eighteen amino acid enantiomers can be resolved sufficiently well for practical application. Only phenylalamine, tyrosine, and tryptophan can be separated by use of Ni2+ as complexation metal at 50 °C. LEC has been used to monitor the decarboxylation of racemic DL-aspartic acid byPseudomonas dacunhae. Analysis of DL amino acid enantiomers in different media was performed at column temperatures of 30 and 50°C by addition of 0.125 mM Cu2+ to the aqueous mobile phase. It was found that the analytical performance is most dependent on the identity of the metal used for complexation; the concentration of the metal was of secondary importance and the column temperature less important still.
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  • 4
    ISSN: 1435-702X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract • Background: Scanty information is available on the changes in conformational structure and composition of human lens capsule in cases of hereditary congenital cataract. The purpose of this study was to use Fourier-transformed infrared (FT-IR) spectroscopy to determine the secondary structure and composition of hereditary cataractous human lens capsule, as compared with normal human lens capsule. • Methods: FT-IR spectroscopy with the Fourier self-deconvolution and curve-fitting program was performed, and second-derivative analysis was used to verify the peak positions and assignments of the IR spectra. • Results: The curve-fit FT-IR spectra revealed that the content of hydroxylysine and arginine were clearly higher in the lens capsule of the hereditary congenital patient, but the content of aspartic acid significantly lower, than in normal human lens capsules. The secondary conformational changes in a-helix, triple helix and random coil structures were important findings in the lens capsule of a hereditary cataractous patient. • Conclusion: Possible alterations in secondary structures and compositions of lens capsule are observed in the hereditary congenital cataractous patient by using FTIR spectroscopy with curve-fitting and second-derivative analysis.
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  • 5
    ISSN: 1434-4726
    Keywords: Bone resorption ; Cholesteatoma ; Keratin-Prostaglandin E2 ; Osteoclast-activating factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Keratin debris is a constant feature in middle-ear cholesteatoma. Keratin prepared from rat skin induced a foreign-body granuloma in the subcutaneous space in the rat. In vitro this granuloma produced high levels of bone-resorbing factors: prostaglandin E2, osteoclast-activating factor, and leucine aminopeptidase. In the in vivo study, keratin-induced granuloma in the rat middle ear caused partial resorption of the cochlear wall. Macrophages, fibroblasts, and osteoclastlike cells were found at bone-resorption areas. These cells appeared to be responsible for bone resorption through production of prostaglandin E2, osteoclast-activating factor, and proteases.
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  • 6
    ISSN: 1435-4373
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  To assess trends in antimicrobial-resistant Salmonella infections from 1989 to 1996 in southern Taiwan, the minimum inhibitory concentrations (MICs) of 14 antibiotics or antibiotic combinations were determined by the agar dilution method for 297 clinical isolates of nontyphoidal Salmonella. The rates of resistance to ampicillin, chloramphenicol, and tetracycline were 65, 67, and 78%, respectively. Resistance to trimethoprim-sulfamethoxazole (TMP-SMX) increased from 25% in 1989–1992 to 35% in 1993–1996 (P=0.057). For new quinolones and extended-spectrum cephalosporins, no resistant strains were encountered. Multiple resistance to more than five antimicrobial drugs doubled from 10.6% in 1989–1992 to 19.7% in 1993–1996. Multiply resistant salmonellae were isolated more commonly from blood samples than from feces (30% vs. 14%, P〈0.05). In Taiwan, ampicillin, chloramphenicol, and even TMP-SMX are no longer the drugs of choice for treatment of serious nontyphoidal Salmonella infections. Extended-spectrum cephalosporins are now the preferred drugs in Taiwan for treatment of invasive Salmonella infections in children.
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  • 7
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 8
    ISSN: 1435-1463
    Keywords: Aortic preparation ; facilins ; dopamine ; adrenaline ; serotonin ; schizophrenia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Biological fluids and tissues extracts were shown to contain biological factors, termed facilins, that facilitate the dopamine-, adrenaline-, and serotonin-mediated aortic contraction at concentrations devoid of any direct effect. Cyproheptadine and phentolamine antagonized the direct contracting effect of biogenic amines, but not the facilitated component of the aortic response thus indicating that the mechanism of action of facilins was unlike that of biogenic amines. Fresh schizophrenics' CSF displayed a stronger facilitating effect than normal CSF on the dopamine-mediated aortic response. This finding, however, was not confirmed with samples kept frozen for prolonged periods of time. Multiple molecular forms of facilins were detected in rabbit serum. Those with a high apparent molecular weight were proteinous and were neither insulin nor other factors known for their contracting effects on the aorta such as epidermal growth factor, transforming growth factor-beta, and platelet-derived growth factor.
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  • 9
    ISSN: 1435-1536
    Keywords: Key words Poly(vinyl alcohol) ; Borax ; Dynamic light scattering ; Viscoelasticity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  The reentrant behavior of Poly(vinyl alcohol) (PVA)–borax aqueous semidilute solutions with a PVA concentration of 20 g/l and borax concentrations varies from 0.0 to 0.20 M was investigated using dynamic light scattering (DLS) and dynamic viscoelastic measurements. Two (fast and slow modes) and three (fast, middle, and slow) relaxation modes of PVA semidilute aqueous solutions without and with the presence of borax, respectively, were observed from DLS measurements. The fast and middle relaxation modes were q 2-dependent (q is the scattering vector) characteristic of diffusive behavior; however, the slow modes were q 3-dependent, characteristic of intraparticle dynamics. The experimental results showed that the slow relaxation mode dominates the DLS relaxation. The DLS slow mode relaxation time, τs, and the viscoelastic modulus G′(ω) and G′′(ω) data had a similar trend and demonstrated reentrant behavior as the borax concentration was increased from 0.0 to 0.20 M, i.e. τs, G′(ω), and G′′(ω) fluctuated with increasing borax concentration. The excluded-volume effect of polymers, charge repulsion among borate ions bound on PVA molecules, and intermolecular cross-linking didiol–borate complexation caused an expansion of the polymer chain; however, the screening effect of free Na+ ions on the negative charge of the borate ions bound on PVA and intramolecular cross-linking didiol–borate complexation led to a shrinkage of the polymer chain. The reentrant behavior was the consequence of the balance between expansion and shrinkage of the PVA–borate complex.
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  • 10
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Observations of the 15:22 UT flare of 24 June 1980 were made using the Very Large Array (VLA) at 6 cm wavelength simultaneously with the Hard X-ray Imaging Spectrometer (HXIS) aboard the Solar Maximum Mission. It was found that at the peak of the impulsive phase, the brightest microwave point appeared to lie between the soft (3.6–8.0 keV) and hard (22–30 keV) X-ray maxima, which were themselves separated by ∼ 20″ (Kundu et al., 1984). Since the publication of these results, we have analyzed the imaging data from the Ultraviolet Spectrometer Polarimeter (UVSP) with the goal of narrowing the possible interpretations of the event. Like the VLA and HXIS, the UVSP observations provide information about the location of the primary electrons; the observations taken together suggest that the fast electrons were symmetrically distributed within the flare loop.
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