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  • 1995-1999  (1,378)
  • 1997  (1,378)
  • Chemistry  (1,279)
  • Biochemistry and Biotechnology  (209)
  • Magnetic resonance imaging  (69)
  • Genetics
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Years
  • 1995-1999  (1,378)
Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Synthesis of polyesters as binders for deinkable inks. VI. Structural analysis of the copolyesterification between o-phthalic anhydride, oleic acid, and trimethylolpropane in bulk at 160°C by high resolution 13C- and 1H nuclear magnetic resonance (13C- and 1H-NMR) (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 3409-3429 
    Details
    ISSN: 0887-624X
    Keywords: polyesters ; bulk copolyesterification ; o-phthalic anhydride ; oleic acid ; trimethylolpropane ; 13C-NMR spectroscopy ; 1H-NMR spectroscopy ; structural analysis ; trimethylolpropane esterification degree ; volumetry ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A detailed structural analysis of the copolyesterification in bulk without any external catalyst at 160°C between o-phthalic anhydride (P), oleic acid (O), and trimethylolpropane (T) with a mol ratio ([—COOH]/[—OH]) = 0.70 has been carried out by high resolution 13C nuclear magnetic resonance (13C-NMR) (DMSO-d6 and CDCl3 solutions), 1H nuclear magnetic resonance (1H-NMR) (CDCl3 solution), and by volumetry. The use of CDCl3 as NMR solvent has allow us to identify several signals that have been assigned to trimethylolpropane monoesters with different esterification degrees in the o-phthalate residue. Identically, we have detected signals assignable to monoesters at the chain ends in structures with different chain lengths. These monoesterified structures have been also confirmed by analyzing samples modified by the diazomethane addition. These modified samples have been also used to determine free acid groups as their methoxylic derivatives by 1H-NMR in CDCl3 solution. We have not observed any detectable signs of gelation nor products produced by secondary reactions. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3409-3429, 1997
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Targeted antisense modulation of inflammatory cytokine receptors (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 55 (1997), S. 72-81 
    Details
    ISSN: 0006-3592
    Keywords: antisense ; receptor targeted delivery ; acute phase response ; IL-6 ; gp 130 ; HepG2 cells ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Antisense technology is potentially a powerful means by which to selectively control gene expression. We have used antisense oligonucleotides to modulate the response of the hepatoma cell line, HepG2, to the inflammatory cytokine, IL-6, by inhibiting the expression of its multifunctional signal transducer, gp130. HepG2 cells respond to IL-6 by upregulating acute phase proteins, such as haptoglobin, by five- to tenfold. Gp130 is central to this response, as the upregulation of haptoglobin is almost completely blocked by the addition of high concentrations (∼100 μg/ml) of a monoclonal antibody to gp 130. Antisense oligodeoxynucleotides complementary to the mRNA encoding gp 130 inhibited the upregulation of haptoglobin by IL-6-stimulated HepG2 cells by about 50%. However, a nonsense sequence also inhibited haptoglobin secretion by about 20%. To improve the specificity and efficiency of action, we targeted the antisense oligonucleotides to HepG2 cells using a conjugate of asialoglycoprotein-poly-L-lysine. The targeted antisense reduced the binding of IL-6 to HepG2 cells, virtually eliminating high affinity binding. In addition, it inhibited haptoglobin upregulation by over 70%. Furthermore, the dose of targeted antisense required for biological effect was reduced by about an order of magnitude as compared with unconjugated antisense. These results demonstrate the potential of antisense oligonucleotides as a means to control the acute phase response as well as the need for a greater understanding of the mechanism and dynamics of antisense molecules as they are developed toward therapeutic application. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 72-81, 1997.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Kinetic modeling of poly(β-hydroxybutyrate) production and consumption by Paracoccus pantotrophus under dynamic substrate supply (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 55 (1997), S. 773-782 
    Details
    ISSN: 0006-3592
    Keywords: PHB ; poly(β-hydroxybutyrate) ; Paracoccus pantotrophus ; dynamic growth ; metabolic modeling ; polymers ; activated sludge process ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The objective of the research was to obtain insights into the behavior of microorganisms under feast/famine conditions as often occur in wastewater treatment processes. The response of microorganisms to such conditions is the accumulation of storage polymers like poly(β-hydroxybutyrate). The research was performed using a pure culture of Paracoccus pantotrophus LMD 94.21. A steady-state C-limited chemostat culture was switched to batch mode and a pulse of acetate was added. As long as external substrate (acetic acid) was present, the organism grew and accumulated poly(β-hydroxybutyrate). After depletion of the external substrate, the stored poly(β-hydroxybutyrate) was used as growth substrate. Poly(β-hydroxybutyrate) accumulation was found to be strongly dependent on the growth rate of the organism before the pulse addition of acetate. Poly(β-hydroxybutyrate) accumulation was correlated to the difference in maximum acetate uptake rate and the acetate required for growth. Based on the interpretation of the experimental results, a metabolically structured model has been set up. This model adequately describes the observed kinetics of the poly(β-hydroxybutyrate) formation and consumption. © 1997 John Wiley & Sons, Inc. Biotechnol Bioeng 55: 773-782, 1997.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Experimental and theoretical studies on the isomerization of allyl thiocyanate to allyl isothiocyanate (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Heteroatom Chemistry 8 (1997), S. 35-43 
    Details
    ISSN: 1042-7163
    Keywords: Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mechanism of isomerization of allyl thiocyanate to allyl isothiocyanate has been investigated both experimentally and theoretically. The kinetic study indicates that the reaction is unimolecular and is not ionic. The entropy of activation suggests strongly that the mechanism involves a cyclic transition state. The rate of reaction was retarded to a small extent in polar solvents relative to that in nonpolar solvents. Ab initio MO calculations indicate, in agreement with the experimental results, that the reaction proceeds through a cyclic transition state, one in which the SCN moiety is almost linear. Thus, this is a [3,3] sigmatropic rearrangement. The charge separation in the transition state was substantial. The retardation of the reaction in polar solvents was attributed to the difference in solvation in the original state and in the transition state. © 1997 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Methyl Aryl Ketones in the Synthesis of Hexaazabicycloicosane Cage ComplexesThis paper is dedicated to Gottfried Huttner, a stimulating teacher, researcher and companion (1997)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 3 (1997), S. 1283-1291 
    Details
    ISSN: 0947-6539
    Keywords: cage compounds ; cobalt ; cyclic voltammetry ; fluorescence spectroscopy ; template synthesis ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The template syntheses of various CoIII-hexaazaicosane-type cage complexes with aromatic substituents are described. The parent template, [Co(sen)]3+ ion {sen = 4,4′,4″-ethylidynetris(3-azabutan-1-amine)}, paraformaldehyde, a methyl aryl ketone and a base were reacted in acetonitrile to give aroyl substituents attached to the fully saturated sarcophagine cage (1-aroyl-8-methyl-3,6,10,13,16,19-hexaazabicyclo[6.6.6]-icosane cobalt(III) ion) and aryl substituents attached to an analogous imine-type cage (2-aryl-8-methyl-3,6,10,13,16,19-hexaazabicyclo[6.6.6]icosa-2-ene cobalt(III) ion). Phenyl, napthyl, phenanthryl, anthracenyl and anthraquinonyl substituents have been bound to the cage simply by this route to give molecules that can act as intercalators in DNA or as photosensitizers attached to reversible redox-active metal centres and can couple an organic two-electron reagent with an inorganic one-electron reagent. An X-ray crystallographic analysis of a phenanthroyl cage complex has also been carried out. These substances and their progeny should be useful as biological probes and fluorescent indicators and for energy capture and conversion.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chem.19970030816
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  • 6
    Electronic Resource
    Electronic Resource
    Tissue reactions to bacteria-inoculated rat lead samples. I. Effect of local gentamicin release through vicinal sponge or solution-dipping (1997)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 35 (1997), S. 217-232 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The effect of local gentamicin release through a vicinal collagen sponge or through preoperative solution-dipping of rat lead samples was investigated in an early-infection model. The efficacy of these methods and their effect on tissue response were determined. It was demonstrated that both methods of local gentamicin release suppress lead-related infectious complications as compared to the control lead, which showed a high presence of inflamed/infected tissues and bacterial growth at each explantation time point. The first day the vicinal collagen sponge was more effective in suppressing the infection than was the solution-dipped lead, probably because there is a faster and higher dose release of gentamicin from the sponge. However, continued implantation time revealed that gentamicin release from the solution-dipped lead was more effective than the sponge. This supports our hypothesis that the presence of lumina are decisive for bacterial growth and persistence of implant-related infections. © 1997 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Tissue reactions to bacteria-inoculated rat lead samples. II. Effect of local gentamicin release through surface-modified polyurethane tubing (1997)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 35 (1997), S. 233-247 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A surface modification technique was developed to achieve controlled release of gentamicin from implanted polyurethane (PU) rat lead samples. PU tubing first was provided with an acrylic acid/acrylamide copolymer surface graft and then loaded with gentamicin. This surface modification technique resulted in release of gentamicin base (GB) and was applied either to the inner luminal surface only (PU-GB-1x) or to both the inner and outer surfaces (PU-GB-2x). First we investigated whether the early tissue response was harmfully compromised when surface-modified rat lead samples were implanted without any infectious challenge. Additionally, the efficacy of this type of local gentamicin therapy was investigated by establishing its effect on tissue response and its ability to prevent lead-related infections after inoculation with Staphylococcus aureus. It was demonstrated that the applied surface modification(s) did not induce adverse effects although an increase in the infiltration of granulocytes and macrophages and an increase in the formation of wound fluid and fibrin were observed. This effect was stronger with PU-GB-2x than with PU-GB-1x. With bacterial inoculation the applied surface modification successfully suppressed the infectious challenge, PU-GB-2x more effectively than PU-GB-1x. PU-GB-2x also was more effective when compared to the gentamicin-delivery methods discussed in the first part of this two-part study, i.e., release through a vicinal gentamicin-containing collagen sponge and preoperative gentamicin solution-dipping of rat lead samples. © 1997 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Purification of the Penicillium citrinum Lipase Using AOT Reversed Micelles (1997)
    Chichester : Wiley-Blackwell
    Journal of Chemical Technology AND Biotechnology 69 (1997), S. 77-85 
    Details
    ISSN: 0268-2575
    Keywords: Penicillium citrinum ; lipases ; purification ; AOT reversed micelles ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: ---This work describes the extraction and back-extraction of a lipase from crude extract of Penicillium citrinum using AOT reversed micelles in isooctane. The effect of pH, ionic strength, AOT concentration on the protein forward and backward transfer at 20°C was studied. The maximum protein forward extraction (32·0%) was achieved at pH 4·0 with a 50 mmol dm-3 acetate buffer containing 100 mmol dm-3 KCl and 100 mmol dm-3 AOT in isooctane. Proteins were back-extracted (82·7%) to a new aqueous phase containing 100 mmol dm-3 pH 8·0 phosphate buffer and 1000 mmol dm-3 KCl. No enzyme activity could be detected either in the micellar phase or in the aqueous phase after protein back-extraction. However, the lipolytic activity was recovered after hydrophobic interaction chromatography on a Phenyl Superose column. The yield obtained for the overall process was 68% for activity, 26·4% for protein recovery and the purification factor was 810-fold. A single protein band at 33000 Da was obtained for SDS-PAGE analysis for the recovered and purified enzyme. © 1997 SCI.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Evidence of the Presence of Dimethylated, Trimethylated and "Refractory' Arsenic Compounds in Estuarine Salt-marsh Halophytes (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 439-450 
    Details
    ISSN: 0268-2605
    Keywords: halophytes ; arsenobetaine ; arsenocholine ; tetramethylarsonium ; arsenosugars ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Five species of halophytes were sampled in the salt marshes of the Tagus estuary, dried, ground and digested. They were further extracted with ethanol and the extracts passed through weak and strong cationic ion-exchange resins, purified through TLC and submitted to pyrolysis mass spectrometry and HPLC-ICP/MS. Arsenic content and hydride-forming arsenic species were verified, in each step, by GF-AA and HG-QFAA. A high content of arsenic was found in the samples of halophytes studied, both di- and tri-methylated arsenic compounds being present. A considerable fraction of this arsenic content seems to be refractory to hydride generation. Moreover, the arsenic fraction found seems to have the same ion-exchange behaviour as the refractory fractions formerly studied in estuarine water.A partial characterization of these structures by pyrolysis-GC-MS suggests the presence of arsenobetaine and arsenocholine compounds. Furthermore, HPLC-ICP/MS data seem to confirm the presence of these compounds. In addition, the latter hyphenated technique strongly suggests the presence of a number of other organoarsenicals including tetramethylarsonium (TMAs), trimethylarsine oxide (TMAO), cacodylate (DMA) and possibly an arsenosugar-type compound. © 1997 by John Wiley & Sons, Ltd.
    Additional Material: 9 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    MRI and MR angiography of vertebral artery dissection (1997)
    Springer
    Neuroradiology 39 (1997), S. 329-340 
    Details
    ISSN: 1432-1920
    Keywords: Key words Arteries ; vertebral ; Arteries ; dissection ; Magnetic resonance imaging ; Magnetic resonance angiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A review of 4,500 angiograms yielded 11 patients with dissection of the vertebral arteries who had MRI and (in 4 patients) MR angiography (MRA) in the acute phase of stroke. One patient with incidental discovery at arteriography of asymptomatic vertebral artery dissection and two patients with acute strokes with MRI and MRA findings consistent with vertebral artery dissection were included. Dissection occurred after neck trauma or chiropractic manipulation in 4 patients and was spontaneous in 10. Dissection involved the extracranial vertebral artery in 9 patients, the extra-intracranial junction in 1, and the intracranial artery in 4. MRI demonstrated infarcts in the brain stem, cerebellum, thalamus or temporo-occipital regions in 7 patients with extra- or extra-intracranial dissections and a solitary lateral medullary infarct in 4 patients (3 with intracranial and 1 with extra-intracranial dissection). In 2 patients no brain abnormality related to vertebral artery dissection was found and in one MRI did not show subarachnoid haemorrhage revealed by CT. Intramural dissecting haematoma appeared as crescentic or rounded high signal on T1-weighted images in 10 patients examined 3–20 days after the onset of symptoms. The abnormal vessel stood out in the low signal cerebrospinal fluid in intracranial dissections, whereas it was more difficult to detect in extracranial dissections because of the intermediate-to-high signal of the normal perivascular structures and slow flow proximal and distal to the dissection. In two patients examined within 36 h of the onset, mural thickening was of intermediate signal intensity on T1-weighted images and high signal on spin-density and T2-weighted images. MRA showed abrupt stenosis in 2 patients and disappearance of flow signal at and distal to the dissection in 5. Follow-up arteriography, MRI or MRA showed findings consistent with occlusion of the dissected vessel in 6 of 8 patients.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002340050418
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