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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of sol gel science and technology 19 (2000), S. 371-375 
    ISSN: 1573-4846
    Keywords: phase separation ; silica ; capillary column ; HPLC ; CEC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Continuous macroporous silica gel networks were prepared in a fused silica capillary, and evaluated in reversed-phase liquid chromatography. Under pressure-driven conditions, considerable dependence of column efficiency on the linear velocity of the mobile phase was observed in spite of the small size of the silica skeletons. A major source of band broadening in the pressure-driven mode was found in the A-term of van Deemter equation. The performance of the continuous silica capillary column in the electro-driven mode was much better than that in the pressure-driven mode.
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  • 2
    ISSN: 1573-904X
    Keywords: cationic lipids ; transfection ; DNA supercoiling ; HPLC ; lipofection ; gene therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. It is a common preconception that supercoiledplasmid DNA is more desirable for the transfection of cells that the relaxedform of the plasmid. This notion has led to the recommendation that aspecification for the minimum amount of plasmid in the supercoiled formshould exist in a gene therapy product. We have tested this notion byexamining the effects of the degree of supercoiling on cationiclipid-mediated gene transfer in vitro and in vivo. Methods. An ion-exchange high performance liquidchromatography (HPLC) method was developed to accurately quantitatethe relative amounts of supercoiled DNA in purified plasmid. A sample of thepurified plasmid was fully relaxed using topoisomerase. Next, the ability ofvarious levels of supercoiled plasmid to transfect mammalian cells wasmeasured. Results. This study suggests that there is no relationbetween the degree of supercoiling and lipofection efficiency. Subsequenttransfection using several different lipofection agents, different celltypes, and an in vivo model support these results. Conclusions. In considering a specification for the amountof supercoiled plasmid in a gene therapy product, it must be noted that therelaxed forms of the plasmid are no less efficient at gene delivery than thesupercoiled forms.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of atmospheric chemistry 36 (2000), S. 81-105 
    ISSN: 1573-0662
    Keywords: hydroxyl radical ; OH ; HPLC ; chromatography ; atmosphere ; air ; troposphere ; determination ; analysis ; air scrubbing ; scavenging ; fluorescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract A preliminary study was carried out toexamine the feasibility of measuring tropospherichydroxyl radicals (OH) by liquidphase scrubbing andhigh performance liquid chromatography (HPLC). Thepotential advantages of this approach are itssimplicity, portability, and low expense. Thesampling system employs glass bubblers to trapatmospheric OH into a buffered solution of salicylicacid (o-hydroxybenzoic acid, OHBA). Rapidreaction of OH with OHBA produces a stable fluorescentproduct, 2,5-dihydroxybenzoic acid (2,5-DHBA), whichis determined by reverse-phase HPLC and fluorescencedetection. Our preliminary field results indicatethat this method is most suitable for OH measurementsin clean tropospheric air, where interferences fromother atmospheric species appear to be negligible orminor relative to polluted air. In clean air, thesampling period is about 45–90 minutes, which yieldsa detection limit of approximately 3–6 ×105 radicalscm-3. During an OHintercomparison experiment at the Caribou samplingsite in Colorado, our liquidphase scrubber method wascompared with the ion-assisted mass spectrometry (MS)method. Our results were within the same range asthose of the ion-assisted MS method (1–5 ×106 radicals cm-3) within our precision atthat time (about ±30–50%). Preliminary testsin Pullman, WA indicated that the method might alsofunction in moderately polluted air by acidifying thescrubbing solution or by adding a scavenger tosuppress interferences. In Pullman, mid-day OHconcentrations were usually in the range of 2–20 ×106 radicals cm-3. Nighttime OHconcentrations were always low, either at or slightlyabove the detection limit.
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  • 4
    ISSN: 1573-1561
    Keywords: Alfalfa extract ; autotoxicity ; bioassay ; chlorogenic acid ; salicylic acid ; HPLC ; GC-MS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Many investigators have attempted to identify the allelochemicals in alfalfa (Medicago sativa), that cause autotoxicity. The autotoxic compounds from fresh alfalfa leaves were separated and quantified, and their biological activity was determined. Chemical separation procedures involved an 80% methanol extract of fresh alfalfa leaves, treatment with activated charcoal, microcrystalline cellulose thin-layer chromatography (MCTLC), and finally separation by Sephadex LH-20 column chromatography. The various fractions were examined further by high-performance liquid chromatography (HPLC). Preliminary identification by HPLC analysis resulted in peaks with retention times close to those of chlorogenic (m/z = 354) and salicylic acid (m/z = 138) standards, and these compounds were confirmed with GC-MS. Several other peaks remain unidentified. Chlorogenic acid occurs in relatively large amounts (0.39 mg/g) in alfalfa aqueous extracts as compared to salicylic acid (0.03 mg/g), and bioassays suggest that chlorogenic acid is involved in alfalfa autotoxicity.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 93-99 
    ISSN: 0935-6304
    Keywords: HPLC ; monolithic column ; silica rod column ; fast separations ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The application of a new silica-based, monolithic-type HPLC-column for fast separations is presented. The column is prepared according to a new sol-gel process, which is based on the hydrolysis and polycondensation of alkoxysilanes in the presence of water soluble polymers. The method leads to “rods” made of a single piece of porous silica with a defined pore structure, i. e. macro- and mesopores. The main feature of silica rod columns is a higher total porosity, about 15% higher than of conventional particulate HPLC columns. The resulting column pressure drop is therefore much lower, allowing operation at higher flow rates including flow gradients. Consequently, HPLC analysis can be performed much faster, as it is demonstrated by various applications.
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  • 6
    ISSN: 0935-6304
    Keywords: Monolithic column ; silica monolith ; HPLC ; capillary liquid chromatography ; capillary electrochromatography ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Two types of monolithic silica columns derivatized to form an ODS phase, one prepared in a fused silica capillary (SR-FS) and the other prepared in a mold and clad with an engineering plastic (poly-ether-ether-ketone) (SR-PEEK), were evaluated. The column efficiency and pressure drop were compared with those of a column packed with 5-μm ODS-silica particles and of an ODS-silica monolith prepared in a mold and wrapped with PTFE tubing (SR-PTFE). SR-FS gave a lower pressure drop than a column packed with 5-μm particles by a factor of 20, and a plate height of 20 μm at a linear velocity below 1 mm/s. SR-PEEK showed higher flow-resistance than the other monolithic silica columns, but they still showed a minimum plate height of 8-10 μm and a lower pressure drop than popular commercial columns packed with 5-μm particles. The evaluation of SR-FS columns in a CEC mode showed much higher efficiency than in a pressure-driven mode.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Chemistry of natural compounds 36 (2000), S. 144-147 
    ISSN: 1573-8388
    Keywords: Artemisia dracunculus ; flavonoids ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Flavonoids in extracts ofArtemisia dracunculus L. are studied. The principal component is identified as pinocembrine. Pinocembrine is analyzed quantitatively using an internal standard. The uncertainties in the chromatographic measurements are estimated.
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  • 8
    ISSN: 0935-6304
    Keywords: HPLC ; industrial wastewater ; process development ; 4-amino-azobenzene-4′,5-disulfonic acid (AABDS) ; 4-amino-azobenzene (AAB) ; 4-amino-azobenzene-4′-sulfonic acid (AABS) ; 4-amino-azobenzene-4′,3,5-trisulfonic acid (AABTS) ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A simple and rapid reversed-phase high-performance liquid chromatographic method for the separation and determination of 4-amino-azobenzene-4′,5-disulfonic acid (AABDS) and its process-related impurities was developed. The separation was achieved on a μ-Bondapak C18 column using 0.15 M ammonium sulfate-acetonitrile (55:45) (v/v) as eluent. A UV-visible spectrophotometric detector fixed at 386 nm was used both for detection and quantitation. The method was used not only for quality assurance but also for process development and wastewater management of AABDS.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 637-643 
    ISSN: 0935-6304
    Keywords: HPLC ; fast separation ; flavan-3-ol ; flavonols ; vegetables ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A fast high-performance liquid chromatography method was used for analysis of prominent flavan-3-ols and flavonols in vegetables. Gradient elution with phosphoric acid-acetonitrile mixtures and phosphoric acid-methanol mixtures allowed fast and complete separation of the studied phenolic compounds within analysis times less than 10 min. The development of two elution gradients using methanol and acetonitrile as modifiers proved to be an excellent approach for the verification of the real polyphenolic composition in vegetables samples because the two optimized methods allowed the separation of the same number of compounds in the same elution order. Diode-array detection was employed for the provisional identification of phenolic compounds that were not available as standards. We preferred methanol as a modifier because it was less toxic and cheaper than acetonitrile. Detection limits ranged between 0.12 and 0.59 μg mL-1. High recoveries of phenolics from fresh vegetables were measured in all studied cases, independent of the phenolic structure, matrix, and vegetable in question. High levels of procyanidins between 150 and 450 mg kg-1 were found in all studied vegetables. Quantification of quercetin and kaempferol glycosides was only possible in marrow and onion, respectively.
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  • 10
    ISSN: 1436-5073
    Keywords: Optimisation ; Taguchi method ; HPLC ; Solid phase extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Sample preparation is the critical step in analysis of residues in biological samples. The development of a ragged method is time-consuming, because a huge number of parameters must be checked. To reduce the number of experiments Taguchi's method was applied in the sample preparation of metabolites of albendazole. During the experiments 11 controllable and 7 noise factors were investigated. From the influence of controllable and noise factors on recovery and standard deviation, conditions for the sample preparation and recovery could be concluded with high accuracy and reliability.
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Accreditation and quality assurance 4 (1999), S. 473-476 
    ISSN: 1432-0517
    Keywords: Key words Validation ; HPLC ; *-Dichlorobenzene ; Naphthalene ; Mothrepellents.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  The determination of dichlorobenzene and naphthalene in commercial repellents used in Spain has been validated. This was done using an isocratic regime, to test the reverse -phase HPLC system with acetonitrile: water 65 : 35 (v: v) as the mobile phase, at 20  °C. This technique is proposed for the modular validation of the HPLC system . The results obtained with this method show good agreement with the results provided by the manufacturers of the mothrepellents.
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  • 12
    ISSN: 1573-4943
    Keywords: Glial cell line-derived neurotrophic factor ; partial reduction ; HPLC ; chemical modification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Recombinant human glial cell line-derived neurotrophic factor has been implicated to have therapeutic potential in the treatment of neurodegenerative diseases. The mature protein is a single polypeptide of 134 amino acid residues and functions as a disulfide-linked dimer. Reduction of the protein with dithiothreitol at pH 7.0 and in the absence of denaturant showed that the single intermolecular cystine bridge was reduced preferentially. Direct alkylation of the generated free sulfhydryl group using iodoacetamide or iodoacetate without denaturant was incomplete. Unfolding the protein in 6 M guanidine hydrochloride prior to the modification showed rapid disulfide scrambling. However, the sulfhydryl-modifying reagent N-ethylmaleimide was able to label quantitatively the free cysteinyl residue in the absence of any added chaotropic agent. By a combination of peptide mapping, Edman degradation, and mass spectrometric analysis, the labeled residue was identified to be Cys101, hence verifying the location of the intermolecular disulfide bond. The modified protein behaved as a noncovalent dimer when chromatographed through a Superdex 75 column under nondenaturing conditions and was comparable in biological activity to an unmodified control sample. The results therefore indicate that the intermolecular disulfide bridge of the protein is not essential for its biological function.
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  • 13
    ISSN: 1573-4943
    Keywords: Arginyl-tRNA synthetase ; 4-fluorotryptophan ; 19F NMR ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Escherichia coli 4-fluorotryptophan-substituted arginyl-tRNA synthetase was biosynthetically prepared and purified from a tryptophan auxotroph which could overproduce this enzyme. A method was developed to separate 4-fluorotryptophan from tryptophan and to determine accurately their contents in the 4-fluorotryptophan-containing proteins. It was confirmed that more than 95% of the tryptophan residues in the purified 4-fluorotryptophan-substituted arginyl-tRNA synthetase were replaced by 4-fluorotryptophan. Studies on the effect of the 4-fluorotryptophan replacement on properties of the enzyme showed that, when compared with the native enzyme, both the specific activity and the first-order rate constant of the fluorinated enzyme decreased by approximately 20% with just slightly higher K m values. CD studies, however, did not reveal any difference between the secondary structure of the native and fluorinated enzymes. In addition, thermal unfolding studies showed that the 4-fluorotryptophan replacement did not significantly affect the thermal stability of the enzyme. We may conclude that the substitution of 4-fluorotryptophan in arginyl-tRNA synthetase had no substantial effect on the structure and function of the enzyme. Finally, a preliminary study of 19F nuclear magnetic resonance spectroscopy of the fluorinated enzyme has shown promising prospect for further investigation of its structure and function with NMR.
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Pharmacy world & science 21 (1999), S. 40-43 
    ISSN: 1573-739X
    Keywords: Laxative abuse ; Factitial diarrhea ; Chronic diarrhea ; Urine analysis ; Bisacodyl ; Bisoxatin ; Phenolphthalein ; Emodine ; Aloe‐emodine ; Rheine ; Danthron ; Picosulphate ; HPLC ; Diode array
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A simple method is proposed for analysis of stimulant laxatives and metabolites of laxatives in urine. All stimulant laxatives commercially available in Germany, Begium and the Netherlands, the diphenylmethane derivatives and the anthraquinones, were included. Chromatography was performed with a standardized isocratic HPLC system with diode array detection ('STIP'), which is commonly used in the Netherlands for toxicological screening. The method was validated by ingestion of a normal dose of the laxatives by human volunteers. In all cases the expected laxative metabolite could be detected in urine twelve hours after intake. Also urine samples of patients, suspected of laxative abuse, were analyzed.
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  • 15
    ISSN: 1573-904X
    Keywords: calcitonin ; polyethylene glycol ; PEGylation ; peptide ; tryptic digestion ; stability ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To separate and characterize the different positional isomers of mono-PEGylated salmon calcitonins (mono-PEG-sCTs) and to evaluate the effects of the PEGylation site on the stability of different mono-PEG-sCTs in rat kidney homogenate. Methods. Mono-PEG-sCTs were prepared using succinimidyl carbonate monomethoxy polyethylene glycol (5,000 Da) and separated by gel-filtration HPLC followed by reversed-phase HPLC. To characterize PEGylated sCTs, matrix-assisted laser desorption ionization time of flight mass spectrometry (M ALDI-TOF MS) and reversed-phase HPLC of the trypsin digested samples were performed. Mono-PEG-sCTs and sCT in rat kidney homogenates were measured by column-switching reversed-phase HPLC with on-line detection of the radioiodinated samples using a flow-through radioisotope detector. Results. Three different mono-PEGylated sCTs were separated by reversed-phase gradient HPLC. From the MALDI-TOF MS analysis, the average molecular weight of mono-PEG-sCTs was confirmed as around 8650 Da. The presence of PEG moiety in the mono-PEG-sCTs was also manifested by the fact that the distance between two adjacent mass spectum lines was 44 Da which corresponds to PEG monomer unit. Tryptic digestion analysis demonstrated that these mono-PEG-sCTs are 3 positional isomers of N-terminus, Lys18- and Lys11-residue modified mono-PEGylated sCTs. The degradation half-life of these 3 positional isomers in rat kidney homogenates significantly increased in order of the N-terminus (125.5 min), Lys11- (157.3 min), and Lysl8-residue modified mono-PEGylated sCT (281.5 min) over the native sCT (4.8 min). Conclusions. Three positional isomers of mono-PEGylated sCTs were purified and characterized. Of these, the resistance to proteolytic degradation was highest for the Lysl8-residue modified mono-PEG-sCT. These studies demonstrate that the in vivo stability of PEGylated sCTs is highly dependent on the site of PEG molecule attachment.
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  • 16
    ISSN: 1573-904X
    Keywords: HI-240 ; nonnucleoside inhibitor ; pharmacokinetics ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The purpose of the present study was to examine the pharmacokinetic features and tissue distribution of N-[2-(2-fluorophenethyl)]-N′-[2-(5-bromopyridyl)]-thiourea (HI-240), a novel non-nucleoside inhibitor of HIV reverse transcriptase with potent anti-viral activity against AZT-sensitive as well as multidrug-resistant HIV-1 strains. Methods. A sensitive and accurate high performance liquid chromatography (HPLC)-based quantitative detection method was established to measure concentrations of HI-240 in pharmacokinetic studies. The plasma concentration-time data were modeled by using the WinNonlin program to estimate the pharmacokinetic parameter values. Results. HI-240 had an elimination half-life of 78.3 ± 2.0 min after i.v. administration and 196.8 ± 3.1 min after i.p. administration. The systemic clearance of HI-240 was 2194 ± 61 ml/h/kg after i.v. administration and 9339 ± 1160 ml/h/kg after i.p. administration. Following i.v. injection, HI-240 rapidly distributed to and accumulated in multiple tissues with particularly high accumulation in adipose tissue, adrenal gland, and uterus+ovary. The concentration of HI-240 in brain tissue was comparable to that in the plasma, indicating that HI-240 easily crosses the blood-brain-barrier. Following i.p. injection, HI-240 was rapidly absorbed with a t1/2ka and a tmax values of less than 10 min. Following oral administration, HI-240 was absorbed with a t1/2ka of 4.2 ±1.1 min and a tmax of 95.1 ± 25.1 min. The intraperitoneal bioavailability was estimated at 23.5%, while the oral bioavailability was only 1%. Conclusions. The HPLC-based accurate and precise analytical detection method and pilot pharmacokinetic studies described herein provide the basis for advanced preclinical pharmacodynamic studies of HI-240. The ability of HI-240 to distribute rapidly and extensively into extravascular compartments and easily cross the blood-brain barrier represent significant pharmacokinetic advantages over AZT.
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  • 17
    ISSN: 1573-904X
    Keywords: pharmacokinetics ; Calphostin C ; HPLC ; perylenequinone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To examine the pharmacokinetic features and metabolism of calphostin C, a naturally occurring perylenequinone with potent antileukemic activity. Methods. HPLC-based quantitative detection methods were used to measure calphostin C levels in lysates of leukemic cells and in plasma of mice treated with calphostin C. The plasma concentration-time data were analyzed using the WinNonlin program. In vitro esterases and a microsome P450 preparation in conjunction with a LC-MS(API-EI) system were used to study the metabolism of calphostin C. Results. An intracellular exposure level (AUC0−6h) of 257 μM·h was achieved after in vitro treatment of NALM-6 cells with calphostin C at a 5 μM final concentration in culture medium. After intraperitoneal (i.p.) injection of a 40 mg/kg nontoxic bolus dose of calphostin C, the estimated Cmax was 2.9 μM, which is higher than the effective in vitro concentration of calphostin C against leukemic cells. Drug absorption after i.p. administration was rapid with an absorption half-life of 24.2 min and the estimated tmax was 63.0 min. Calphostin C was cleared with an elimination half-life of 91.3 min. An inactive and smaller metabolite (calphostin B) was detected in plasma of calphostin C-treated mice with a tmax of 41.3 min. Esterase (but not P450) treatment of calphostin C in vitro yielded an inactive metabolite (calphostin B) of the same size and elution profile. Conclusions. Target plasma calphostin C concentrations of potent antileukemic activity can be reached in mice at nontoxic dose levels. This pilot pharmacokinetic study of calphostin C combined with the availability of the described quantitative HPLC method for its detection in cells and plasma provide the basis for future preclinical evaluation of calphostin C and its potential as an anti-leukemic drug.
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  • 18
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 217-221 
    ISSN: 0935-6304
    Keywords: HPLC ; UV detection ; linear range ; method validation ; Beer-Lambert law ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Determination of the linear range is one of the main concerns in validation of an HPLC analysis method. It is particularly important since single point calibration will be then used routinely. We proposed an iterative methodology to handle this problem. The idea was, at each step, to test statistically whether the following point belonged to the same regression line. The methodology was then used to evaluate quantitatively the effect on linear range of a shift in detection wavelength or of the detector bandwidth. Although experimental results were globally in accordance with spectroscopic theory, magnitudes observed were rather large. So the linear range could vary by a factor of over 2 with changes in conditions that remained within the range of current practical values. Changes in detection wavelength were limited to about fifteen nm around λmax and the detector used was considered to be representative of modern high-performance UV detectors. The question of how to take consequences in method validation into account was raised. The solution proposed recommended that the validation was undertaken in conditions as close as possible to those where the method would be conducted routinely. This means with the same instrumentation and on the product of interest for analyses.
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  • 19
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    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 483-486 
    ISSN: 0935-6304
    Keywords: HPLC ; alumina ; evaporative light-scattering detection ; non-polar lipids ; wax esters ; sterol esters ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---This study describes the performance and capacity of alumina as stationary phase in an HPLC-ELSD (evaporative light-scattering detection) method optimized for the separation of the non-polar lipid classes hydrocarbons, wax esters, sterol esters, triacylglycerols, and sterols, including quantitative determination of these lipid classes in natural samples. By using gradient elution and constant equilibration times between injections, highly reproducible separations of triacontane, stearyl oleate, and cholesterol oleate were accomplished with a binary mobile phase system. Phase A contained 0.5% tetrahydrofuran in hexane and phase B 20% isopropanol and 20% tetrahydrofuran in hexane. The same system was also used to determine the non-polar lipid classes in a zooplankton sample, the major lipid class being wax esters, followed by triacylglycerols, sterol esters, sterols, and hydrocarbons. Substantial amounts of an unknown compound, possibly acylated glyceryl ethers, were also found. The equilibration time of alumina was relatively slow compared to a polyvinyl alcohol stationary phase used earlier by the authors and calibration curves for different lipid classes were more uniform and linear with alumina.
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  • 20
    ISSN: 0935-6304
    Keywords: HPLC ; nitrotyrosine ; nitrotocopherol ; analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---For three decades, high performance liquid chromatography has proven itself to be a powerful, flexible, and inexpensive tool for basic and clinical research. Recent advances in our understanding of disease have prompted a demand for more sensitive and selective methods of routine bioanalysis, particularly with respect to the determination of oxidative metabolites and biomarkers of oxidative stress. Multidimensional detectors utilizing coulometric arrays offer a solution to these research needs. The challenge to the bioanalyst is now to creatively apply HPLC-ECD technology to promising research and clinical enterprises.
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  • 21
    ISSN: 0935-6304
    Keywords: HPLC ; di(2-ethylhexyl) phthalate ; migration ; foods and food simulants ; PVC cling film ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 22
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    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 103-108 
    ISSN: 0935-6304
    Keywords: HPLC ; stationary phase ; copper-amine complex ; aromatic amines ; polyaromatic hydrocarbons ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Chromatographic silica (10 μm) was chemically modified with the silylating agent: [3-(2-aminoethyl)aminopropyl]trimethoxysilane (AEAPTS). The reaction product was characterized by elemental analysis and infrared and 13C and 29Si NMR spectra. The chemically modified silica was treated with Cu(II) in methanol medium. This cation was strongly adsorbed through complexation by the pendant ethylenediamine groups attached to the silica surface. The complex formed on the silica surface was shown to be stable in both aqueous and non-aqueous media. The aim of Cu(II) immobilization is to use this new material as a stationary phase in High Performance Liquid Chromatography (HPLC). Separations of synthetic mixtures of aromatic amines and of polyaromatic hydrocarbons were undertaken using 150×3.9 mm HPLC columns packed with the modified silica, with and without copper ions, to follow the influence of the cation on the chromatographic separation and to verify the efficiency of the new stationary phase for HPLC.
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  • 23
    ISSN: 0935-6304
    Keywords: Tebuthiuron ; GC-MS ; HPLC ; drinking water ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---No abstract
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  • 24
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    Microchimica acta 128 (1998), S. 19-29 
    ISSN: 1436-5073
    Keywords: automation ; sample preparation ; chromatography ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The purpose of this review is to discuss the strategic problems of automating sample preparation (SP) for high performance liquid chromatography (HPLC). There is a general feeling that SP is the bottleneck of many HPLC procedures. Despite numerous reports of successful automation of SP, there are still many laboratories using manual or semiautomated SP procedures. This calls for a reevaluation of the present situation.
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  • 25
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    Microchimica acta 129 (1998), S. 19-27 
    ISSN: 1436-5073
    Keywords: competitive ; non-competitive ; homogeneous ; heterogeneous ; pre-column immunoassay ; post-column immunoassay ; sandwich ; epitope ; on-line immunoassay ; off-line immunoassay ; laser-induced fluorescence ; microchip system ; HPLC ; CE ; digoxin digoxigenin ; solid phases affinity column ; urine ; plasma ; ELISA ; FAB fragments ; estrogen ; leukotriene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The combination of immunoassays with separation techniques such as chromatography and electrophoresis can provide both selectivity and sensitivity that is competitive with any method currently available for molecular analysis. Immunoassays can be carried out on-line and off-line, pre and post separation. The on-line post separation mode is the most promising for routine analysis because of the high throughput that can be achieved but also provides the greatest challenge with regard to compatibility of the interfaced systems. This paper reviews the various approaches that have been researched from a practical immunochemical point of view with emphasis on the special problems incurred with matrix compatibility for on-line post separation systems.
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    Molecular diversity 4 (1998), S. 47-52 
    ISSN: 1573-501X
    Keywords: chromatography ; HPLC ; library ; purification ; SPE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In the early days of combinatorial chemistry, much attention focused on preparation of large libraries for lead discovery. Recently, though, the focus has shifted toward smaller, more focused libraries for lead optimization. These focused libraries generally consist of individual discrete compounds. Biological assay requirements often require compounds of high purity, thus development of automated high throughput purification methods has received new attention in the past several years. This paper covers automated high throughput purification methods that have been applied to libraries of discrete compounds. Literature published through February 1998 is included. Purification methods discussed include extraction methods, scavenger methods, solid phase extraction, and preparative HPLC.
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  • 27
    ISSN: 0887-624X
    Keywords: (1→6)-2,5-anhydro-D-glucitol ; HPLC ; optical resolution ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The cyclopolymerization of 3,4-di-O-allyl-1,2 : 5,6-dianhydro-D-mannitol (1) was carried out using BF3·OEt2 and t-BuOK. The polymer obtained by the polymerization with BF3·OEt2 mainly consisted of (1→6)-bonded 3,4-di-O-allyl-2,5-anhydro-D-glucitol as the five-membered constitutional repeating unit, though it contained a small amount of other cyclic repeating units. On the other hand, during the polymerization using t-BuOK, the stereoregular polymer (1→6)-linked 3,4-di-O-allyl-2,5-anhydro-D-glucitol (2) was synthesized via a regio- and stereoselective mechanism. Cleavage of the allyl ether linkage in polymer 2 occurred to produce the polymer consisting of only 2,5-anhydro-D-glucitol units, i.e., (1→6)-2,5-anhydro-D-glucitol (3). Chromatographic enantioseparation of chloroquine and tröger base has been performed on (3,5-dimethylphenyl)carbamate and 4-methylbenzoate derivatives of 3 as a chiral stationary phase for high-performance liquid chromatography. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 901-909, 1998
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  • 28
    ISSN: 1612-1112
    Keywords: Capillary electrochromatography ; Pesticides, insecticides ; Environmental analysis ; Radioactivity ; Electroosmosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The applicability of capillary electrochromatography to the automated analysis of pesticides and phthalate esters that are of environmental concern was assessed. Reversed phase packing materials were compared. Column to column and run to run reproducibility was established. Peak height with an internal standard gave the best reproducibility. Faster analysis than alternative HPLC methods was demonstrated for a mixture of the insecticide pirimicarb and related pyrimidines. The relationship between the concentration of an analyte in a sample and at the detector was determined by the use of radio-labelled14C-pirimicarb. The volume fraction of the liquid zone was 0.64. The possibility of electroosmosis through the pores is discussed with reference to the Rice-Whitehead model for electroosmotic flow in a capillary. A new parameter, the effective pore size is used in equations for electroosmosis through porous packings.
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  • 29
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    Pharmaceutical research 15 (1998), S. 1270-1274 
    ISSN: 1573-904X
    Keywords: blood-brain barrier (BBB) ; drug transport ; prediction of brain uptake ; immobilized artificial membrane (IAM) ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The present study evaluates immobilized artificial membrane (IAM) chromatography for predicting drug permeability across the blood-brain barrier (BBB) and outlines the potential and limitations of IAMs as a predictive tool by comparison with conventional methods based on octanol/water partitioning and octadecylsilane (ODS)-HPLC. Methods. IAM- and ODS-HPLC capacity factors were determined in order to derive the hydrophobic indices log kIAMand log kwfor two sets of compounds ranging from very lipid soluble (steroids) to more hydrophilic agents (biogenic amines). The uptake of the compounds across the in vivoBBB expressed as brain uptake index (BUI) has been correlated with these HPLC capacity factors as well as octanol/ water partition (ClogP) and distribution coefficients (log D7.4). Results. For both test groups log kIAMcorrelates significantly with the respective log BUI of the drug (r2= 0.729 and 0.747, p 〈 0.05), whereas with log kw, log D7.4and ClogP there is only a correlation for the group of steroids (r2= 0.789, 0.659 and 0.809, p 〈 0.05) but not for the group of biogenic amines. There is a good correlation between log kIAMand log kw, ClogP or log D7.4for the group of steroids (r2= 0.945, 0.867 and 0.974, p 〈 0.01) but not for the biogenic amines. Conclusions. All physico-chemical descriptors examined in this study equally well describe brain uptake of lipophilic compounds, while log kIAMis superior over log D7.4, ClogP and log kwwhen polar and ionizable compounds are included. The predictive value of IAMs combined with the power of HPLC holds thus great promise for the selection process of drug candidates with high brain penetration.
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    Pharmaceutical research 15 (1998), S. 1414-1418 
    ISSN: 1573-904X
    Keywords: cartilage permeability ; matrix metal loprotease inhibitors ; hydrophilicity ; cartilage location ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To develop an in vitro cartilage permeation model for cartilage permeability study and to evaluate the effects of molecular hydrophilicity and cartilage location on the permeability of articular cartilage to matrix metalloprotease inhibitors. Methods. An in vitro cartilage permeation model was developed and utilized to determine the permeability of articular cartilage to the matrix metalloprotease inhibitors of different hydrophilicity. Permeability coefficients were obtained by measuring the steady-state flux of the inhibitor compounds. HPLC methods were also developed and employed for the analysis of drug levels in assay media. Results. The relationship between permeability and hydrophilicity of drug molecules was examined. Results indicated that the permeability coefficient increased with increasing hydrophilicity of the molecule. Additionally, the relationship between the permeability and the location of the cartilage section within the animal joint was investigated. Our results showed that the drug molecules penetrated faster in the surface layer cartilage than in the deep layer cartilage. Conclusions. Increasing the hydrophilicity of a molecule would increase its permeability across articular cartilage. The in vitro cartilage permeation model developed could be used to rank order drug compounds according to their cartilage permeability profiles and to aid in drug selection and development.
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  • 31
    ISSN: 1573-1111
    Keywords: Crown ether ; amino acids ; enantioselection ; membrane transport ; chiral receptors ; HPLC
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    Topics: Chemistry and Pharmacology
    Notes: Abstract A chiral crown ether incorporating a methyl α-d-mannopyranoside unit displayed pronounced enantioselection of amino acids in partition liquid chromatography experiments involving solvent systems of limited miscibility: water–ethanol–2,2,4-trimethylpentane. The same system has been used for amino acid transport across a liquid membrane containing the crown ether, and in liquid–liquid extraction experiments. Remarkable enantioselection has been noted for amino acids in all the processes studied.
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  • 32
    ISSN: 0899-0042
    Keywords: calcium antagonist ; stereoselective analytical method ; isradipine enantiomers ; Chiral OJ ; HPLC ; GC ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: rac-Isradipine is a dihydropyridine type calcium antagonist. Its calcium entry blocking effect is due primarily to the (+)-(S)-enantiomer. This study describes a sensitive enantioselective method for the determination of isradipine in human serum. Following alkaline extraction into hexane, the enantiomers of isradipine are separated quantitatively by high-performance liquid chromatography on a Chiralcel OJ column at 39°C. The collected fractions were evaporated and assayed using capillary gas chromatography on a HP 50+ column with nitrogen selective detection. Using 2.0 ml of serum, 0.7 nmol/1 (0.26 ng/ml) of each enantiomer could be determined with acceptable precision. The method has successfully been used to measure (+)-(S)- and (-)-(R)-isradipine concentrations in samples from volunteers after intravenous and oral administration of isradipine. Chirality 10:808-812, 1998. © 1998 Wiley-Liss, Inc.
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    Chirality 10 (1998), S. 430-433 
    ISSN: 0899-0042
    Keywords: Whelk-O 1 ; chromatography ; HPLC ; enantiodifferentiation ; heterocycles ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In concert with a larger study of the processes by which chiral stationary phase CSP 1 differentiates between enantiomers, we have investigated the chromatographic separation of the enantiomers of a series of aryl-substituted heterocycles of systematically varied structure. A mechanistic picture of how these and similar resolutions occur is emerging. The mechanistic hypothesis described herein is of predictive value. Chirality 10:430-433, 1998. © 1998 Wiley-Liss, Inc.
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    Chirality 10 (1998), S. 492-498 
    ISSN: 0899-0042
    Keywords: racemate ; enantiomer ; HPLC ; chiral stationary phase ; benzoylcellulose ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The advantages that can be gained from derivatization of various racemic aliphatic and aromatic alcohols prior to enantiomeric chromatographic separation have been systematically investigated for a series of benzoate derivatives. Three cellulose-based CSPs available in the pure polymeric form - tribenzoyl cellulose (TBC), meta-methylbenzoyl cellulose (MMBC), and para-methylbenzoyl cellulose (PMBC) - were selected and several benzoate derivatives varying in the nature and the position of the substituent on the benzoyl group were prepared and analysed. TBC clearly gives the broadest application range, and among the different benzoate esters the best selectivity was generally obtained with either the 4-methoxybenzoate or the 4-methylbenzoate derivatives. Based on these results, some empirical rules could be formulated for optimizing the enantiomeric separation of racemic alcohols, which make up one of the most important classes of chemical substances used as drugs and biocides, or as building blocks for their synthesis. An application of this approach to the preparative separation of the enantiomers of a drug intermediate is also shown. Chirality 10:492-498, 1998. © 1998 Wiley-Liss, Inc.
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    Journal of High Resolution Chromatography 21 (1998), S. 253-257 
    ISSN: 0935-6304
    Keywords: Edible oils ; lipids in foods ; HPLC ; Polycyclic Aromatic Hydrocarbons (PAHs) ; off line LC-LC ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 36
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    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 63-68 
    ISSN: 0884-3996
    Keywords: ethanol ; hexachlorobenzene ; porphyria ; oxidative stress ; spontaneous urinary chemiluminescence ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Hexachlorobenzene (HCB) administration to rats induces porphyria cutanea tarda, characterized by high levels of urinary porphyrins (〉40 μg/day) and accumulation of highly carboxylated porphyrins in liver (〉15 μg/g of tissue). Ethanol administration, under the conditions employed, was not porphyrinogenic and was able to diminish some of the responses elicited by HCB. Furthermore, ethanol and/or HCB administration leads to organ disturbances that involve oxidative stress. We have measured the changes in urinary chemiluminescence (CL) levels, as part of a systematic evaluation of the metabolic alterations in rats chronically treated with ethanol and/or HCB. The results, that constitute the first set of urinary CL data obtained from an animal model system, indicate that the measurement of the spontaneous urinary CL can constitute a fast, simple and sensitive method to evaluate disturbances associated with oxidative stress. © 1998 John Wiley & Sons, Ltd.
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    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 85-90 
    ISSN: 0884-3996
    Keywords: stopped-flow ; chemiluminescence ; multicomponent analysis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The stopped-flow technique was employed to measure chemiluminescent emission from the reaction of a mixture of oxalate and proline with a chemiluminescence reagent, tris(2,2′-bipyridine)ruthenium(III), or Ru(bpy)33+. Ru(bpy)33+ is a versatile reagent and is often used in bioanalytical applications, including the detection of certain drugs and their metabolites, for example. Unfortunately, Ru(bpy)33+ has not yet been fully examined as a possible chemiluminescence reagent for simultaneous kinetic determinations. In this work, a differential reaction rate method, based on simple least squares regressions of the pseudo-first order decay data, was used to resolve two compounds, oxalate and proline, reacting simultaneously with Ru(bpy)33+. Our results indicate that stopped-flow analyses with Ru(bpy)33+ could provide a viable method for simultaneous determinations of unresolvable analytes of environmental and pharmaceutical importance. © 1998 John Wiley & Sons, Ltd.
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  • 38
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    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 287-293 
    ISSN: 0884-3996
    Keywords: electroporation ; UV light ; oxidative stress ; catalase ; superoxide dismutase ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Escherichia coli JM101 cells were subjected to pore-forming electric fields, irradiation with ultraviolet light or oxidative stress by either the lipoxygenase products 9- and 13-hydroperoxyoctadecadienoic acids (9- and 13-HPOD) or hydrogen peroxide. It was found that all chemico-physical stresses enhanced ultraweak light emission from the bacterial cells, the most effective treatment being electroporation (up to 20-fold increase in luminescence compared to the control value), followed by oxidative stress with 9- or 13-HPOD (up to 4-fold increase) and irradiation with UV light (up to 2.8-fold increase). Bacterial luminescence was always in the red edge of the spectrum and was paralleled by changes in membrane oxidative index and specific activity of catalase and superoxide dismutase. © 1998 John Wiley & Sons, Ltd.
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  • 39
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    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 307-309 
    ISSN: 0884-3996
    Keywords: immunoassay ; biological markers ; myocardial infarction ; diagnostic sensitivity ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Three new immunochemiluminometric assays for quantitation of cardiac markers, i.e. creatine kinase isoenzyme MB (CK-MB), myoglobin and cardiac troponin I (cTnI), were evaluated with the Sanofi Access analyser. The complete profile requires 20 min to perform, the method being suitable in true stat situations. In patients with early myocardial infarction (median time of sample collection: 210 min from onset, range 30-450; n = 44), the diagnostic sensitivity of Access cTnI was 66%, compared with 80% for myoglobin, and 43% for CK-MB. For comparison, cTnI, with an automated immunofluorimetric assay was also measured (sensitivity, 45%; p 〈 0.05 vs. Access cTnI). Our data confirmed myoglobin as the first biochemical marker to appear elevated after infarction. However, cTnI may be a more sensitive marker for early detection of cardiac damage than initially thought, when determined by an ultrasensitive method such as an immunochemiluminometric assay. © 1998 John Wiley & Sons, Ltd.
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  • 40
    ISSN: 0884-3996
    Keywords: bioluminescence ; adrenalin ; noradrenalin ; photophores ; HPLC ; mesopelagic fish ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The presence of adrenalin (E) and noradrenalin (NE) was found by HPLC both in the photophores and at other tissue levels of numerous species of mesopelagic fish in The Strait of Messina, with the aim of determining the incidence of these catecholamines in photophores, in light transmission and the eventual presence at other tissue levels. © 1998 John Wiley & Sons, Ltd.
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  • 41
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    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 273-278 
    ISSN: 0884-3996
    Keywords: diabetes ; leukocytes ; monocytes ; extracellular matrix ; non-enzymatic glycosylation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Non-enzymatic glycosylation (NEG) of collagen has been previously shown to significantly influence the reactive oxygen metabolism (ROM) of phagocytic cells in healthy subjects. Considering the role of NEG in the pathophysiology of diabetes, we have further analysed the oxidative metabolism of polymorphonuclear cells (PMNs) and monocytes in 23 patients with non-insulin dependent diabetes mellitus in order to better elucidate a possible pathogenic role of NEG of the extracellular matrix in long-term complications of diabetes. Experiments were performed in triplicate on native-collagen and glycated-collagen coated vials, using a chemiluminescence (CL) assay. Results show that PMNs from diabetic patients display a significant increased basal and zymosan-induced CL activity with respect to controls that are not related to the glycation state of the substrate. Conversely, the CL activity of monocytes induced by zymosan shows a decrease in diabetic patients with respect to healthy volunteers (p 〈 0.05). Moreover, monocyte CL was reduced by the glycated matrix, both in healthy volunteers and in diabetic subjects (p 〈 0.05 and p 〈 0.01, respectively). These data highlight a complex role of phagocytic leukocytes in the pathophysiology of extracellular matrix alterations secondary to NEG that are typically present in clinical conditions such as diabetes or ageing. © 1998 John Wiley & Sons, Ltd.
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  • 42
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    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 349-354 
    ISSN: 0884-3996
    Keywords: β-D-galactosidase ; enzyme immunoassay ; chemiluminescence ; 5-bromo-4-chloro-3-indolyl-β-D-galactopyranoside (X-gal) ; thyroxine ; indole derivative ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: We developed a novel chemiluminescent assay of β-D-galactosidase (β-gal) based on the chemiluminescence of indole. 5-Bromo-4-chloro-3-indolyl-β-D-galactopyranoside (X-gal) was used as a substrate for β-gal and also as a light emitter. X-gal was hydrolysed by β-gal to liberate free indoxyl, followed by oxidation to indigo dye, and simultaneously produces hydrogen peroxide (H2O2). H2O2 reacts with the residual X-gal in the presence of horseradish peroxidase (HRP) to emit light. The measurable range of β-gal obtained by this method was 6 × 10-14 mol/L to 6 × 10-11 mol/L; the detection limit was 3 amol/assay. This chemiluminescent assay could be applied to an enzyme immunoassay of thyroxine using β-gal as the enzyme label. © 1998 John Wiley & Sons, Ltd.
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  • 43
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    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 21-24 
    ISSN: 0884-3996
    Keywords: 2-D imaging ; chemiluminescence ; auto-oxidation ; hydration ; cereal products ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Two-dimensional (2-D) spatial distributions of ultra-weak chemiluminescence (photon imaging) from auto-oxidizing and water-hydrated cereal food products were measured by means of a high-sensitivity 2-D photon counting system - an intensified charge coupled device (CCD) camera. The 2-D images obtained reveal the dynamics and emission patterns of very slow auto-oxidation reactions and much faster processes of water penetration into cereal products. The enhancement of chemiluminescence by the addition of water appears to involve complex processes with an inhomogenous spatial and energy distribution within cereal products. The effect of antioxidants, free radical promoters and scavengers suggests that oxidative radical reactions contribute significantly to the observed chemiluminescence. The possible involvement of hydrophilic interactions, H2O-biopolymers and recombination of trapped radicals is also discussed. © 1998 John Wiley & Sons, Ltd.
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  • 44
    ISSN: 0884-3996
    Keywords: CRF ; TAC ; lipids ; apolipoproteins ; oxLDLAb ; diet ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Lipoprotein abnormalities are common in uraemia and are considered important factors for development of atherosclerosis and progression of renal disease. Reduction of total antioxidant capacity (TAC) and lipid peroxidation (LP) probably play a major role in both processes. The aim of this study was to assess the effect of renal function, dietary manipulation and lipids on TAC of uraemic patients with different chronic renal failure (CRF). Sixty patients (36M, 24F), aged 60 ± 12 years were divided into five groups according to serum creatinine levels (sCr, mg/dl) -  CRFI, 1.5-3; CRFII, 〉 3-5.5; CRFIII, 〉 5.5; CRFIV, 〉 3 on vegetarian supplemented diet (SD); CRFV haemodialysis patients (HD)-and investigated for TAC by enhanced chemiluminescent assay, autoantibodies against oxidized LDL (oxLDLAb), lipids, apolipoprotein AI, B, Lp(a) and uric acid (UA). The results were compared to a control group of 19 people (8M, 11F), aged 52 ± 11 years with sCr 〈 1.5. TAC increased significantly with the progression of CRF and was strongly related to both sCr and UA. Lipids and SD did not show any influence on TAC. Unexpectedly, lipid peroxidation did not correlate to TAC, neither to sCr or UA. HD accounted for a mild reduction of both TAC and LP. Patients on SD showed a marked reduction of LP as compared to patients with a similar degree of renal failure (CRF-III) but on conventional diet. Our results suggest that elevated TAC in uraemia is likely to be dependent on increased UA levels and does not seem to induce an effective protection in vivo from oxidative stress. In conclusion, TAC does not appear to be a reliable method for assessing the oxidative susceptibility of CRF patients. © 1998 John Wiley & Sons, Ltd.
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  • 45
    ISSN: 0884-3996
    Keywords: chemiluminescence ; PCR ; contamination ; polymorphism ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Minisatellite analysis is commonly used in forensic disputes but can also be applied to the investigation of cell contamination. Such a problem arises, for example, when transplantation is performed. The presence of contamination has been investigated by other authors using radioactive methods. In the present study we describe a method that allows the detection of contamination with high sensitivity without using radioactive substances. Our technique is based on the use of polymerase chain reaction (PCR) amplification of minisatellite sequences (VNTR), followed by chemiluminescent detection. In particular, biotin-labelled dCTP is included in the PCR mixture and detection of PCR products is obtained following the CSPD chemiluminescent protocol (Southern-Light Nucleic Acid Detection Systems). We applied this method to artificial mixes of DNA of two individuals with alleles of different sizes. We performed progressive dilutions of an individual DNA into the other's DNA and revealed a contamination of 1 in 2500 cells. We also tested our technique searching for maternal contamination in cord blood samples in 60 cases and revealed a 18.3% contamination. The technique that we set up proves to be a very sensitive one which could be applied not only to the detection of maternal cells in cord blood but also in studying any other kind of contamination. © 1998 John Wiley & Sons, Ltd.
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  • 46
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    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 295-301 
    ISSN: 0884-3996
    Keywords: plant virus ; diagnosis ; transgenic plants ; non-radioactive probes ; digoxigenin ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Due to costs in using and disposing of radiochemicals and to health considerations, we have been developing applications which include non-isotopic detection of DNA and proteins using chemiluminescence. Our major interests are in the detection of viral nucleic acids and in the analysis of transgenic plants. Generally, probes were labelled with digoxigenin, either by the random priming method or by PCR, and then detected with CSPD or CDP-Star. We routinely use a tissue blotting protocol for diagnosing TYLCV, a plant virus becoming a pest in the Mediterranean region. Test results were comparable with those using the same radiolabelled probe. When total nucleic acids are extracted from the plant samples and used in dot-blot or Southern blot assays, viral DNAs are promptly detected by chemiluminescence. In transgenic plants, chemiluminescence was used to detect the transgene on genomic Southern blots, the transgenic mRNAs on Northern blots, and the transgenic protein on Western blots. In Southern and Northern blots, the quality of the results obtained was usually satisfactory, but not as good as with a radiolabelled probe, the main problem being the signal-to-background ratio. Our goal is now to improve the quality of results in demanding applications such as genomic Southern blots, by reducing the background on membranes. © 1998 John Wiley & Sons, Ltd.
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  • 47
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    Keywords: chemiluminescence ; β-galactosidase ; tetracyclines ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The observation that tetracyclines inhibit the biosynthesis of β-galactosidase in Escherichia coli to a greater extent than other antibacterials was exploited for the development of a chemiluminometric method to detect residues of this class of antibiotics in milk. The procedure involves the incubation of a milk sample with 107 CFU/ml of an E. coli strain in the presence of IPTG, an inducer of β-galactosidase, and of EGTA, a chelator of calcium ions, followed by a 1000-fold dilution and measurement of the residual enzymatic activity using the chemiluminogenic substrate Galacton. Chemiluminometry proved an essential tool in this procedure because the extensive dilution of the sample, necessary to avoid light quenching by turbidity, results in an insufficient level of β-galactosidase activity to be measurable by colorimetry. This tetracycline galactosidase (TG) test has been validated and compared in the field to existing commercial screening assays for antibiotics. Its detection limit for tetracyclines ranges between 40 and 65 μg/kg, which is below the European maximum residue limit (MRL = 100 μg/kg) in milk. No other antibacterials, at concentrations commonly expected in milk, were found to interfere with the TG test. Strategies to avoid false positive reactions possibly arising from very high somatic cell counts will be reported elsewhere. © 1998 John Wiley & Sons, Ltd.
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    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 355-363 
    ISSN: 0884-3996
    Keywords: hydrogen peroxide ; sodium hypochlorite ; reactive oxygen species ; chemiluminescence ; luminol ; lucigenin ; penicillin ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Evidence is provided that the amplifiers luminol and lucigenin react with different reactive oxygen species (ROS), depending on the ROS-generating system used. H2O2 is used to produce calibration curves for luminol- and lucigenin-amplified chemiluminescence. With this chemiluminescence generator we characterized the specificity and sensitivity of luminol- and lucigenin-amplified chemiluminescence and also studied penicillin G, a known enhancer of luminol-amplified chemiluminescence. The combination of luminol and lucigenin in reciprocally changing concentrations is effective in an additive manner, but the weak amplifier penicillin increases luminol-amplified chemiluminescence distinctly more than in an additive manner in different combinations. Lucigenin-amplified chemiluminescence is increased by penicillin at about 1% of the optimum concentration of penicillin; increasing concentrations of penicillin are less and less effective. On the other hand, low lucigenin concentrations enhance penicillin-amplified chemiluminescence at optimum penicillin concentrations more than in an additive manner. Fe2+ does not alter luminol-, lucigenin- or penicillin-amplified chemiluminescence. Co2+ increases luminol-amplified chemiluminescence by a factor of 100. Lucigenin- and penicillin-amplified chemiluminescence are minimally enhanced by Co2+. Cu2+ enhances luminol-amplified chemiluminescence with increasing concentrations by a factor of 1000. Lucigenin-amplified chemiluminescence increases also by the factor of 1000, but the concentration-reaction curve is not as steep. NaOCl enhances H2O2/Fe2+-driven luminol-amplified chemiluminescence in a concentration-dependent manner by a factor of 104 (in the highest concentration of 10 mmol/L) and lucigenin amplified chemiluminescence only by a factor of about 25. Catalase (CAT) abolishes luminol-, lucigenin- and penicillin-amplified chemiluminescence completely, whereas superoxide dismutase (SOD) has no effect on luminol- or penicillin-amplified chemiluminescence, but enhances lucigenin-amplified chemiluminescence five-fold increasingly with increasing SOD activity. © 1998 John Wiley & Sons, Ltd.
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  • 49
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    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 371-378 
    ISSN: 0884-3996
    Keywords: bioluminescence ; luciferase ; ATP ; immobilization ; glass ; poly-L-lysine ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The bioluminescent reaction catalysed by firefly luciferase has become widely established as an outstanding analytical system for assay of ATP. When used in solution, luciferase is unstable and cannot be re-used, a problem that can be partially circumvented by immobilizing the enzyme on solid substrates. Transparent glass is especially advantageous over alternative immobilizing matrices, since it allows most of the emitted photons to be detected. We report a new method for luciferase immobilization on glass which does not require prior silanization and glutaraldehyde activation, thus saving preparation time and minimizing enzyme inactivation. Our method is based on the co-immobilization by adsorption of luciferase (from a firefly lantern extract) and poly-L-lysine (PL) on non-porous glass strips. Luciferase immobilized in this way exhibits minimal variations in intersample activity, high sensitivity for ATP detection (linear luminescence responses down to 50 nmol/L) and good stability (full activity for at least 60 days when stored at -80°C). PL-mediated immobilization of luciferase on glass strips provides an attractive strategy for the design of specific ATP biosensors, with potential in industry, environmental screening, medicine and biological research. © 1998 John Wiley & Sons, Ltd.
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  • 50
    ISSN: 0884-3996
    Keywords: bile acids ; chemiluminescence ; superoxide ; antioxidants ; micelles ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The antioxidant activity of a representative series of free, glycine- and taurine-conjugated bile acids was evaluated by two different chemiluminescent assays: (a) the enhanced chemiluminescence system based on horseradish peroxidase and luminol/oxidant/enhancer reagent, and (b) the hypoxanthine/xanthine oxidase/Fe2+-EDTA/luminol system. Bile acids were studied at final concentrations ranging from 1 to 28 mmol/L. All of the bile acids studied inhibited the steady-state chemiluminescent reaction and the extent of inhibition depended upon the structure of the bile acids, whereas the duration was related to bile acid concentration. The mechanism of the light inhibition is probably due to trapping of oxygen free radicals generated in the chemiluminescent reactions, within bile acid micelles. The free radicals trapped into micelles reduced the formation of luminol radicals and consequently the light output; when the micelles were saturated, the oxygen free radicals in solution again produced luminol radicals. The micelle interaction with reactive oxygen species could be a physiological mechanism of defence against the toxicity of those species in the intestinal content. On the other hand, alterations in bile acid organ distribution, concentration and composition leads to a membrane damage caused by their detergent-like properties, which could be associated to oxygen free radical production. © 1998 John Wiley & Sons, Ltd.
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  • 51
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    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 365-369 
    ISSN: 0884-3996
    Keywords: Vibrio fischeri ; LuxR ; lux ; bioluminescence ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: We have recently suggested that the expression of V. fischeri right lux operon is initiated from two sites, the first located upstream of the luxI gene, while the second seems to be located upstream of the luxC gene. The transcription from both sites is negatively controlled by H-NS protein. E. coli MC4100 rpoS hns mutant harbouring the V. fischeri luxCDABE genes showed constitutive mode and 70,000-fold higher luminescence than the wild-type cells. The present study shows that the expression of luxCDABE genes in E. coli MC4100 wild-type cells is also controlled by LuxR protein in the absence of the autoinducer. The co-presence of a ptac-controlled luxR gene in a trans position to a plasmid carrying the luxCDABE genes resulted in 100,000 times higher luminescence. In the absence of the autoinducer, the presence of the luxR gene under its own regulated control resulted in about 100-200-fold increase of luminescence from the luxC upstream site. Taken together, it seems that the LuxR protein initiates the formation of the V. fischeri lux system cloned in E. coli from two sites located upstream and downstream of the luxI gene. Only the activation of the first site requires the presence of the autoinducer, whereas the second site is fully activated by LuxR protein in the absence of the autoinducer. © 1998 John Wiley & Sons, Ltd.
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  • 52
    ISSN: 0884-3996
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: No Abstract
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  • 53
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    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 139-145 
    ISSN: 0884-3996
    Keywords: electrochemiluminescence ; metal ions ; 2,3-diaminonaphthalene ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Electrochemiluminescence (ECL) of 200 ppm 2,3-diaminonaphthalene (2,3-DAN) was studied alone and in conjunction with 100 ppm of 34 different metal and non-metal ions and revealed three relatively intense ECL responses from interactions of 2,3-DAN with Au+, Fe+3 and V+5. ECL responses from Cr+6 or Ru+3 with 2,3-DAN were less intense, but noteworthy, as was the coloured fluorescent product of the non-metal ion Se+4 interaction with 2,3-DAN. Several intense 2,3-DAN-metal ion ECL reactions were studied in greater detail and revealed various titration curves with ionic detection limits in the low ppm range, using a fixed level (200 ppm) of 2,3-DAN. © 1998 John Wiley & Sons, Ltd.
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  • 54
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    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 185-188 
    ISSN: 0884-3996
    Keywords: Vibrio fischeri ; H-NS ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: We have recently proposed that the expression of V. fischeri right lux operon is controlled by two promoters; the first one located upstream of the luxI gene, while the second one seems to be located upstream of the luxC gene. The transcription from both promoters is negatively controlled by H-NS protein. Escherichia coli MC4100 rpoS hns mutant that carried the V. fischeri lux system with a deletion in either the luxI or luxR gene showed a constitutive mode and more than 10,000-fold higher luminescence than the control cells. The present study shows that neither luxR nor luxI are required for the transcription of the luxCDABE genes in an H-NS deficient strain of E. coli. The MC4100 rpoS hns mutant harbouring the luxCDABE-carrying plasmid showed constitutive mode and 70,000-fold higher luminescence than the wild-type cells. The question whether both the left and the right operons of V. fischeri lux system are controlled by H-NS was addressed with the aid of plasmids harbouring the lacZ gene fused with luxR or luxI. In MC4100 hns rpoS background, luxR and luxI genes were very early and actively transcribed, as judged by the strong β-galactosidase activity that was developed at early stage of growth. The β-galactosidase activity in the wild-type cells was 20-40 times lower and occurred mainly during the second half of the growth cycle. It thus appears that H-NS inhibits the transcription of three promoters of the lux system of V. fischeri; the left operon that codes for LuxR protein and two promoters located upstream and downstream to luxI gene. © 1998 John Wiley & Sons, Ltd.
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  • 55
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    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 285-285 
    ISSN: 0884-3996
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: No abstract.
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  • 56
    ISSN: 0884-3996
    Keywords: free radicals ; antioxidant ; total antioxidant capacity ; Trolox ; Insulin-dependent diabetes mellitus (IDDM) ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Free radicals are considered to be important factors involved in many physiopathological processes. Several methods have been proposed for studying the mechanisms of antioxidant protection against free radical-induced injury, including the measurement of the total antioxidant capacity (TAC) in body fluids, based on enhanced chemiluminescence. This technique is calibrated against Trolox™ and assay results are expressed as μmol/L of Trolox equivalents. Since many of the complications induced by diabetes appear to be mediated by oxygen free radical generation, we have investigated serum antioxidant capacity in a group of healthy subjects and in insulin-dependent diabetic (IDDM) subjects. A statistically significant difference was noticed in TAC values between the IDDM group and the young control group. Even if the biological meaning of this significant reduction in TAC remains to be explained, an overproduction of precursors of reactive oxygen free radicals and/or a decreased scavenger systems efficiency can be associated with the increased risk of atherosclerotic cardiovascular disease in diabetic patients. © 1998 John Wiley & Sons, Ltd.
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  • 57
    ISSN: 0884-3996
    Keywords: peroxynitrite ; antioxidants ; luminol ; acetaminophen ; phenols ; catecholamines ; norepinephrine ; isoproterenol ; epinephrine ; SIN-1 ; sydnonimines ; polyphenols ; catechins ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: This study is based on a simple chemical interaction of peroxynitrite (O=N—O—O-) and luminol, which produces blue light upon oxidation. Since peroxynitrite has a half-life of about 1 s, a drug known as linsidomine (SIN-1) is used as a peroxynitrite generator. Peroxynitrite can oxidize lipids, proteins and nucleic acids. Upon the stimulation of inflammation and/or infection, macrophages and neutrophils can be induced to produce large amounts of peroxynitrite, which can oxidize phenols and sulphhydryl-containing compounds. Therefore, phenols and sulphhydryls eliminate peroxynitrite. This is an example of the Yin-Yang hypothesis e.g. oxidation-reduction. Acetaminophen (Tylenol®) can inhibit fever and some types of pain without being a particularly effective anti-inflammatory. Since it is a phenol, it could act as a nitration target for peroxynitrite. Then peroxynitrite, the possible cause of pain and elevated temperature, might be destroyed in the reaction. Acetaminophen is a phenolic compound which produces a clear inhibitory dose-response curve with peroxynitrite in its range of clinical effectiveness. Whether acetaminophen actually works as we suggest is to be proven. Three different types of reaction could decrease the amount of peroxynitrite: (a) interference with base-catalysed opening of the SIN-1 molecule; (b) destruction of one or both substances needed to form it -  superoxide and/or nitric oxide; when the SIN-1 degrades to superoxide and nitric oxide, the former may be destroyed by superoxide dismutase (SOD); (c) peroxynitrite may react directly with phenols (mono-, di-, tri- and tetraphenols), possibly by nitration. Nordihydroguaiaretic acid and 2-hydroxyestradiol (catechol estrogen) are potent inhibitors of luminol light emission. Epineprine, isoproterenol, pyrogallol, catechol and ascorbic acid (a classic antioxidant) are all inhibitors of luminol chemiluminescence. Isoproterenol, norepinephrine/and epinephrine first inhibit light but overall stimulate the light production. Initially, SIN-1 degrades to produce peroxynitrite, which reacts with luminol to produce blue light. If any of three catecholamines are present with the reaction that produces light, there is an initial inhibition of light production, and then a marked stimulation. A possible reason for this is that these catechols are oxidized and the metabolized phenol stimulates the production of light from luminol. Also, during oxidation of catecholamines superoxide is sometimes formed, which could stimulate production of peroxynitrite. This simple screening system is introduced to find useful antioxidants against peroxynitrite. © 1998 John Wiley & Sons, Ltd.
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  • 58
    ISSN: 1075-2617
    Keywords: Cα,α-disubstituted amino acids ; crystal structure ; molecular dynamics ; conformation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystal structures of three fully protected tripeptides containing the Dφg residue (Cα,α-diphenylglycine) in the central position are reported, namely Z-Gly-Dφg-Gly-OMe (a), Z-Gly-Dφg-Aib-OMe (b) and Z-Aib-Dφg-Aib-OMe (c). The molecular conformations are quite unusual because the Dφg residue adopts a folded conformation in the 310-helical region when the following residue adopts a folded conformation of opposite handedness (peptidesbandc). In contrast, the Dφg residue adopts the more frequently observed fully extended conformation when the following residue adopts a semi-extended conformation (peptidea). These findings are in agreement with the theoretical calculations on Ac-Dφg-Aib-NHCH3 and Ac-Aib-Dφg-NHCH3 also reported in this work. © 1998 European Peptide Society and John Wiley & Sons, Ltd.
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  • 59
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    Journal of Peptide Science 4 (1998), S. 364-368 
    ISSN: 1075-2617
    Keywords: trans-cis amide equilibrium ; dynamic nuclear magnetic resonance ; fulleroproline ; NOE differential spectroscopy ; proline ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 1H NMR study of fulleroproline derivative Ac-Fpr-OtBu and its Pro analogue Ac-l-Pro-OtBu over a range of temperatures in toluene-d8 solution has enabled the comparison of their equilibrium and activation parameters for the trans/cis interconversion around the amide partial double bond. © 1998 European Peptide Society and John Wiley & Sons, Ltd.
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  • 60
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    Journal of Peptide Science 4 (1998), S. 335-343 
    ISSN: 1075-2617
    Keywords: cyclic peptides ; human growth hormone ; lactam cyclisation ; side chain effects ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conditions for the synthesis of i-(i+4) side chain-to-side chain head-to-tail Lys→Glu and Glu→Lys linked cyclic peptides related to hypoglycaemic analogues of human growth hormone hGH [6-13] have been examined. The success of the cyclisation reaction with the corresponding resin-bound, partially protected linear peptides was found to be both reagent as well as sequence dependent, with competing inter-chain oligomerisation predominating in some cases. The results also indicated that protection with the bulky Fmoc group of the amino acid residues immediately adjacent to the side chain-deprotected Lys and Glu residues, which participate in the cyclisation reaction, enhanced the rate of lactam formation. © 1998 European Peptide Society and John Wiley & Sons, Ltd.
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  • 61
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    Journal of Peptide Science 4 (1998), S. 371-377 
    ISSN: 1075-2617
    Keywords: biotinylgramicidin ; peptide synthesis ; planar lipid bilayers ; ion channel ; biotin-avidin interactions ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new linear gramicidin analog bearing a biotinyl group grafted on C-terminal part was designed to study ligand-receptor interactions. The C-terminal alcohol in the native peptide was first replaced by an amino group. Then the peptide was synthesized on a polystyrene resin functionalized by the 2-chlorotrityl chloride following a biotinylation performed in solution. This new N′-biotinyl-(EDA)15-Gramicidin A was reconstituted in planar lipid bilayers and exhibited channel activities similar to those of natural gramicidin, with unitary conductance value about 30 ps in 1 m KCl. Furthermore this ionophore activity was quenched by addition of streptavidin in the surrounding medium. Our system is an outstanding tool for monitoring ligand-receptor interactions and could be used for designing a new biosensor. © 1998 European Peptide Society and John Wiley & Sons, Ltd.
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  • 62
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    Journal of Peptide Science 4 (1998), S. 378-388 
    ISSN: 1075-2617
    Keywords: HLA-B27 ; circular dichroism ; thermal denaturation ; computer-aided ligand design ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: High-affinity ligands of non-peptidic nature, binding to the class I major histocompatibility complex protein HLA B*2705 whose expression is strongly linked to the pathogenesis of the autoimmune disease ankylosing spondylitis, should give way to a selective immunotherapy by blocking or antagonising the interaction with autoreactive T cell clones. Here we present experimental data on the binding of modified peptides, designed to optimally bind to HLA-B*2705 by filling a hydrophobic binding pocket (pocket D) with nonencoded aromatic amino acids. Three peptides with altered side chains (alpha-naphthylalanine, beta-naphthylalanine and homophenylalanine) in position 3 were synthesised. The thermal denaturation profiles of the HLA protein in complex with the modified peptides, monitored by circular dichroism spectroscopy, showed a significant shift towards higher melting temperatures with respect to the parent T cell epitope. The proposed binding mode of the nonnatural peptides was checked by site-directed mutagenesis of the pocket D, hypothesised to accommodate the large hydrophobic side chains. Reducing the size and depth of the pocket by mutating Leu l56 into Trp only affects the binding of the non-natural ligands, thus providing experimental evidence that the nonnatural peptide amino acids bind as predicted to the host MHC protein. © 1998 European Peptide Society and John Wiley & Sons, Ltd.
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  • 63
    ISSN: 1075-2617
    Keywords: conformational analysis ; lipo-amino acid ; membrane activity ; NMR ; peptide antibiotic ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have synthesized by solution-phase methods two analogues of the 11-residue lipopeptaibol antibiotic trichogin GA IV in which the N-terminal n-octanoyl group is replaced either by an N-acetylated 2-amino-2-methyl-l-undecanoic acid or by an N-acetylated α-aminoisobutyric acid. CD, FTIR absorption, and NMR analyses unequivocally show that the main structural features of trichogin GA IV are preserved in these analogues. Since only the peptide containing the lipophilic chain exhibits membrane-modifying properties, these results strongly support the view that moving the long acyl moiety from the Nα-blocking group to the side chain of the N-terminal extra-residue does not affect the conformational properties or the membrane activity of trichogin GA IV. © 1998 European Peptide Society and John Wiley & Sons, Ltd.
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  • 64
    ISSN: 1075-2617
    Keywords: HIV-1 Tat ; dipeptidyl peptidase IV ; 1H NMR spectroscopy ; MD calculations ; structure-activity relationships ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: On the basis of our recent results, the N-terminal sequence of HIV-1 Tat protein as a natural competitive inhibitor of dipeptidyl peptidase IV (DP IV) is supposed to interact directly with the active site of DP IV hence mediating its immunosuppressive effects via specific DP IV interactions. Of special interest is the finding that amino acid substitutions of the Tat(1-9) peptide (MDPVDPNIE) in position 5 with S-isoleucine and in position 6 with S-leucine led to peptides with strongly reduced inhibitory activity suggesting differences in the solution conformation of the three analogues. Therefore, 1H NMR techniques in conjunction with molecular modelling have been used here to determine the solution structure of Tat(1-9), I5-Tat(1-9) and L6-Tat(1-9) and to examine the influence of amino acid exchanges on structural features of these peptides. The defined structures revealed differences in the conformations what might be the reason for different interactions of these Tat(1-9) analogues with certain amino acids of the active site of DP IV. © 1998 European Peptide Society and John Wiley & Sons, Ltd.
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  • 65
    ISSN: 1075-2617
    Keywords: modes of action ; anti-bacterial ; cecropins ; morphology ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Natural anti-bacterial peptides cecropin B (CB) and its analogs cecropin B-1 (CB-1), cecropin B-2 (CB-2) and cecropin B-3 (CB-3) were prepared. The different characteristics of these peptides, with amphipathic/hydrophobic α-helices for CB, amphipathic/amphipathic α-helices for CB-1/CB-2, and hydrophobic/hydrophobic α-helices for CB-3, were used to study the morphological changes in the bacterial cell, Klebsiella pneumoniae and the leukemia cancer cell, HL-60, by scanning and transmission electron microscopies. The natural and analog peptides have comparable secondary structures as shown by circular dichroism measurements. This indicates that the potency of the peptides on cell membranes is dependent of the helical characteristics rather than the helical strength. The microscopic results show that the morphological changes of the cells treated with CB are distinguishably different from those treated with CB-1/CB-2, which are designed to have enhanced anti-cancer properties by having an extra amphipathic α-helix. The morphological differences may be due to their different modes of action on the cell membranes resulting in the different potencies with lower lethal concentration and higher concentration of 50% inhibition (IC50) of CB on bacterium and cancer cell, respectively, as compared with CB-1/CB-2 (Chen et al. 1997. Biochim. Biophys. Acta 1336, 171-179). In contrast, CB-3 has little effect on either the bacterium or the cancer cell. These results provide microscopic evidence that different killing pathways are involved with the peptides. © 1998 European Peptide Society and John Wiley & Sons, Ltd.
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  • 66
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    Journal of Peptide Science 4 (1998), S. 426-435 
    ISSN: 1075-2617
    Keywords: HIV-1 ; viral protein ; solution structure ; sequence motifs ; helices ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Vpr, one of the accessory gene products encoded by HIV-1, is a 96-residue protein with a number of functions, including targeting of the viral pre-integration complex to the nucleus and inducing growth arrest of dividing cells. We have characterized by 2D NMR the solution conformations of bioactive synthetic peptide fragments of Vpr encompassing a pair of H(F/S)RIG sequence motifs (residues 71-75 and 78-82 of HIV-1 Vpr) that cause cell membrane permeabilization and death in yeast and mammalian cells. Due to limited solubility of the peptides in water, their structures were studied in aqueous trifluoroethanol. Peptide Vpr59-86 (residues 59-86 of Vpr) formed an α-helix encompassing residues 60-77, with a kink in the vicinity of residue 62. The first of the repeated sequence motifs (HFRIG) participated in the well-defined α-helical domain whereas the second (HSRIG) lay outside the helical domain and formed a reverse turn followed by a less ordered region. On the other hand, peptides Vpr71-82 and Vpr71-96, in which the sequence motifs were located at the N-terminus, were largely unstructured under similar conditions, as judged by their CαH chemical shifts. Thus, the HFRIG and HSRIG motifs adopt α-helical and turn structures, respectively, when preceded by a helical structure, but are largely unstructured in isolation. The implications of these findings for interpretation of the structure-function relationships of synthetic peptides containing these motifs are discussed. © 1998 European Peptide Society and John Wiley & Sons, Ltd.
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  • 67
    ISSN: 1075-2617
    Keywords: CD ; FT-IR ; gp120-CD4 interaction ; HIV-1 ; structure-function studies ; solid-phase peptide synthesis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have previously demonstrated that a 23-amino acid peptide derived from the V3 loop of the surface glycoprotein of the HIV-1 strain MN is able to bind CD4 and to enhance HIV-1 infection. Further studies have suggested that the peptide/CD4 interaction induces an increase in both CD4 expression and CD4/gp120 binding affinity. This paper describes the biological and physico-chemical characterization of three analogues of reduced sequence that have been designed in order to identify the minimum active sequence of this peptide corresponding to the MN-HIV-1 principal neutralizing domain. Biological studies indicate that the entire sequence is required for biological activity and that the sequence 1-18 presents an inhibitory activity. CD and FT-IR absorption data are discussed here in order to identify possible structure-function correlations. © 1998 European Peptide Society and John Wiley & Sons, Ltd.
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  • 68
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    Journal of Peptide Science 4 (1998), S. 461-470 
    ISSN: 1075-2617
    Keywords: monitoring ; solid phase peptide synthesis ; FT-IR spectroscopy ; difficult sequences ; aggregation ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Aggregation phenomena of growing peptides on the resin have seldom been investigated. We report here how conformations are determined by FT-IR spectroscopy. Therefore the sequence 80-99 of HIV 1-protease was synthesized. After every coupling a resin sample was taken out of the reaction column and a FT-IR spectrum recorded. The results were compared with the UV monitoring obtained from another synthesis of the same peptide. © 1998 European Peptide Society and John Wiley & Sons, Ltd.
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  • 69
    ISSN: 1075-2617
    Keywords: peptide surfactant ; surfactin ; conformation ; micelles ; biosurfactant ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have studied the effects of extrinsic environmental conditions on the conformation of surfactin, a heptapeptide biosurfactant from Bacillus subtilis, in aqueous solutions. It has been made clear that temperature, pH, Ca2+ ions and the synthetic nonionic surfactant hepta-ethylene glycol (C12E7) affect the conformation of surfactin in aqueous solutions. The β-sheet formation reached a maximum at 40°C both in presence and absence of (C12E7) and the nonionic surfactant enhances the β-sheet formation even at 25°C. Ca2+ induced the formation of a-helices and caused this transition at 0.3 mm with surfactin monomers or at 0.5 mm with surfactin micelles, but above these transition concentrations of Ca2+ β-sheets were observed. In micellar solution the β-sheet structure was stabilized at pH values below 7 or upon addition of Ca2+ in concentrations above 0.5 mm. Our results indicated that the bioactive conformation of surfactin is most likely the β-sheets when the molecules are assembled in micelles. The β-sheet structure in micelles could be retained by tuning the micelles. Surfactin micelles could be tuned in the bioactive conformation by manipulating pH, temperature, Ca2+ or (C12E7) concentrations in surfactin solutions. Our results strongly indicated that Ca2+ and other molecules (such as C12E7) may function as directing templates in the assembly and conformation of surfactin in micelles. Thus, we suggest environmental manipulation and template-aided micellation (TAM) as a new approach for preparing predesigned micelles, microemulsions or micro-spheres for specific application purposes. © 1998 European Peptide Society and John Wiley & Sons, Ltd.
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  • 70
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    Journal of Peptide Science 4 (1998), S. 471-478 
    ISSN: 1075-2617
    Keywords: N-hydroxy peptides ; peptides ; ligands ; MHC ; solid-phase synthesis ; MHC, major histocompatibility complex ; BSA, bovine serum albumin ; DMEM, Dulbecco s modified Eagle'rsquo;s medium ; FITC, fluorescein isothiocyanate ; TcR, T cell receptor, Alloc, allyloxycarbonyl ; Bzl, benzyl ; NMM, N-methyl morpholine ; DIC, diisopropylcarbodiimide ; TIS, triisopropylsilane ; DIPEA, diisopropylethylamine ; HOBt, 1-hydroxybenzotriazole ; DBU, 1,8-diazabicyclo[5.4.0]undecen-7-ene ; HATU, O-(7-azabenzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate ; HOAt, 7-aza-1-hydroxybenzotriazole ; CPY, carboxypeptidase Y ; APM, aminopeptidase M ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A novel class of major histocompatibility complex class I (MHC-I) ligands containing an N-hydroxy-amide bond was designed on the basis of the natural epitope SIINFEKL, and synthesized on solid phase. The capacity of these compounds to bind to the MHC-I molecule H-2Kb and to induce T cell responses was analysed in comparison with the corresponding glycine containing variant of SIINFEKL. Binding to the MHC molecule was diminished by the N-hydroxy group at positions 2 and 3 of the oligomer and improved in the case of positions 4, 5, 6 and 7. No change was seen for position 1. The efficacy of T cell stimulation was strongly reduced by the modification of all positions except for position 1. A complete loss of activity was found for the N-hydroxy variant in positions 4 and 6. N-Hydroxy amide-containing peptides displayed an enhanced stability to enzymatic degradation. This new class of MHC ligand can become instrumental as immunomodulatory reagent in various disease situations. © 1998 European Peptide Society and John Wiley & Sons, Ltd.
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  • 71
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    Journal of Peptide Science 4 (1998), S. 479-485 
    ISSN: 1075-2617
    Keywords: anti-HIV agent ; Env-derived peptide ; SPC3 ; V3 domain ; HIV infection ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: SPC3 is a peptide construct (eight branches of the GPGRAF motif) derived from the consensus sequence present at the apex of the third variable domain of the human immunodeficiency virus (HIV) envelope (Env). It presents a potent anti-HIV activity and is currently tested in phase II clinical trials (FDA protocol 257A). Its mode of action remains unclear. It was thought that SPC3 exerts its effect both during HIV interaction with CD4+ cells but also through interference either with a post-binding event or with Env processing. Accordingly, SPC3 was supposed to be able to bind and to enter CD4+ cells. In this work, we addressed these points. SPC3 was found to interact with CD4+ cell membrane with a K0.5 value in the range of 500 nm. The binding of SPC3 to CD4+ cells involves its interaction with a cell membrane associated protein which is pronase sensitive and different from CD4. This interaction was similar from 2 to 37°C. The maximum binding occurred at acidic pH whereas the interaction was inhibited in alkaline conditions. We observed also that SPC3 was internalized rapidly into the cells - the maximal intracell amount was reached within 30 min - where it remained stable for at least 24 h. Altogether, these data suggest that SPC3 can exert its antiviral activity via interference with events occurring at the cell surface but also into the target cell. © 1998 European Peptide Society and John Wiley & Sons, Ltd.
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  • 72
    ISSN: 1075-2617
    Keywords: enkephalins ; DPDPE ; opioid agonists ; δ-receptor ; fluorine containing amino acid ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Analogs of Met-enkephalin and [d-Pen2, d-Pen5]enkephalin (DPDPE) containing the partially fluorinated amino acid 4,4-difluoro-2-aminobutyric acid (DFAB) in the 2- or 3-position of the peptide sequence were synthesized and their opioid activities and receptor selectivities were determined in vitro. The linear fluorinated [d-DFAB2, Met5-NH2]enkephalin showed μ and δ agonist potencies comparable to those of natural [Leu5]enkephalin. The partially fluorinated DPDPE analogs behaved differently as compared with their non-fluorinated correlates. While l-amino acid substitution in position 3 of DPDPE usually resulted in higher δ agonist potency than d-amino acid substitution, [d-DFAB3]DPDPE turned out to be a more potent δ agonist than [l-DFAB3]DPDPE. Furthermore, [d-DFAB3]DPDPE showed over 100-fold higher δ agonist potency than [d-Abu3]DPDPE (Abu=2-aminobutyric acid), indicating that the fluorine substituents interact favorably with a δ opioid receptor subsite. © 1998 European Peptide Society and John Wiley & Sons, Ltd.
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  • 73
    ISSN: 1075-2617
    Keywords: substance P analogues ; synthesis of pseudopeptide amides ; small cell lung cancer ; inhibition of proliferation ; SCLC, small cell lung cancer ; BN, bombesin ; GRP, gastrin releasing peptide ; SP, substance P ; pHOPA, 4-hydroxyphenyl-acetyl ; MPA, 2-amino-3-methylpentane ; cycloLeu, 1-amino-1-cyclopentane-carbonyl ; d-MePhe, d-N-methyl-phenylalanyl ; LAH, lithium aluminium hydride ; MES, mercaptoethanesulfonic acid ; DCC, dicyclohexylcarbodiimide ; DCU, dicyclohexylurea ; Dnp, 2,4-dinitrophenyl ; HOPfp, pentafluorophenol ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Small cell lung cancer (SCLC) cell lines produce and secrete various peptide hormones, e.g. bombesin (BN)/gastrin releasing peptide (GRP) like peptides that are proposed to function as their autocrine growth factors. To inhibit the proliferative effect of these hormones we have synthesized short chain BN[7-14]-analogues replacing the C-terminal peptide bond by a methylene-amino (-CH2NH-) unit and introducing d-Phe or d-Ser into position 12. As several substance P (SP) analogues were found to inhibit the growth of SCLC cells, some short chain SP-analogues have been synthesized. (Pseudo)octapeptides were synthesized in solution, by fragment condensation using the DCC/HOPfp method. Fragments and SP-analogues were synthesized stepwise using pentafluorophenyl esters. The resistance to hydrolysis of the reduced peptide bond made permitted exact quantification of the Leuψ(CH2NH)Leu pseudopeptide in hydrolysates. The binding ability of both types of peptides to BN-receptors on Swiss 3T3 mouse fibroblast cells and their antiproliferative effect on NCI-H69 human SCLC cell line have been tested and compared with a short chain SP-antagonist pHOPA-d-Trp-Phe-d-Trp-Leu-Leu-NH2 (R) previously described as a potent inhibitor of SCLC proliferation. While BN-analogues showed weak activity in inhibition of proliferation of SCLC cells, SP-analogues 6: d-MePhe-d-Trp-Phe-d-Trp-Leuψ(CH2NH)-Leu-NH2 and 7: d-MePhe-d-Trp-Phe-d-Trp-Leu-MPA, in spite of greatly diminished affinity towards the BN-receptor, inhibited SCLC proliferation more effectively than R (6: IC50=2 μm, 7: IC50=5 μm and R: IC50=10 μm). Moreover, 6 inhibited the respiratory activity of SK-MES 1 epithelial type of lung carcinoma cells in proliferating but not in the quiescent state, suggesting that the antiproliferative effect of these compounds is not due to simple cytotoxicity. These short chain analogues of SP might be promising candidates as therapeutic agents in the treatment of SCLC. © 1998 European Peptide Society and John Wiley & Sons, Ltd.
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  • 74
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    Journal of Peptide Science 4 (1998), S. 253-265 
    ISSN: 1075-2617
    Keywords: Opioids ; enkephalin ; selectivity ; conformation ; NMR ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conformational studies of enkephalins are hampered by their high flexibility which leads to mixtures of quasi-isoenergetic conformers in solution and makes NOEs very difficult to detect in NMR spectra. In order to improve the quality of the NMR data, Leu-enkephalin was synthesized with 15N-labelled uniformly on all amide nitrogens and examined in a viscous solvent medium at low temperature. HMQC NOESY spectra of the labelled Leu-enkephalin in a DMSOd6/H2O mixture at 275 K do show numerous NOEs, but these are not consistent with a single conformer and are only sufficient to describe the conformational state as a mixture of several conformers. Here a different approach to the structure-activity relationships of enkephalins is presented: it is possible to analyse the NMR data in terms of limiting canonical structures (i.e. β- and γ-turns) and finally to select only those consistent with the requirements of δ selective agonists and antagonists. This strategy results in the prediction of a family of conformers that may be useful in the design of new δ selective opioid peptides. © 1998 European Peptide Society and John Wiley & Sons, Ltd.
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  • 75
    ISSN: 1075-2617
    Keywords: Peptide nucleic acid monomers ; PNA synthesis ; disulphide linkers ; solid-phase synthesis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new simple solid-phase method has been developed for synthesizing Boc-protected peptide nucleic acid (PNA) monomers. An immobilized backbone 3 was built on Expansin® resin using an ester disulphide handle: 2-hydroxypropyl-dithio-2′-isobutyric acid (HPDI). The base acetic acids of thymine 5, Z-cytosine 9, Z-adenine 12, and 6-O-benzyl guanine 17 were prepared and coupled to the immoblized backbone. The HPDI handle was cleaved under mild conditions by cyanolysis or assisted hydrolysis with tris(2-carboxyethyl)phosphine (TCEP) to give undamaged PNA monomers. These monomers were coupled to form oligomers by solid-phase method with another disulphide linkage: aminoethyldithio-2-isobutyric acid (AEDI) grafted on an amino-functionalized TentaGel® resin, using in situ neutralization and TBTU as activating reagent. Final cleavage of the AEDI linker gave PNA bearing a cysteamide residue that could be useful for optimizing PNA properties. Oligomers of up to 16 residues long were assembled. © 1998 European Peptide Society and John Wiley & Sons, Ltd.
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  • 76
    ISSN: 1075-2617
    Keywords: Synthetic peptide library ; one-bead-one-compound ; partial cleavage ; soluble phase screening ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A library system was developed for the discovery of bioactive peptides. Library synthesis and peptide sequencing was performed on a solid support while the screening for bioactivity was done with peptides in solution. The peptides were synthesized by split and mix, one-bead-one-peptide library synthesis, using a Tentagel S-NH2 solid support with a loading of approximately 100 pmol/bead. The major part of the peptide was connected to the support by a single acid-labile linker and a minor part of the peptide was acid-stabile attached to the polymer. The percentage of acid-stabile attached peptides could easily be controlled during modification of the amino functionalities of the resin at the start of the process. The cleavage rate of the acid-labile attached peptide from the resin depends on the composition of the cleavage mixture. When cleavage conditions were carefully controlled, a three-step partial cleavage protocol allowed for convergent bioactivity screening on peptide libraries using only one type of acid-labile linker. The partial cleavage and convergent screening procedure was repeated three times, after which the bead containing the bioactive peptide was sequenced. As such a bead still contained acid-stabile attached peptide, the Edman sequencing was straightforward and repetitive yields were excellent because the immobilized peptide was not washed out. © 1998 European Peptide Society and John Wiley & Sons, Ltd.
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  • 77
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    Journal of Peptide Science 4 (1998), S. 289-293 
    ISSN: 1075-2617
    Keywords: Bradykinin antagonist ; dimer ; diaminodicarboxylic acid ; bridge residue ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enhancement of a ligand's interaction with a receptor through presenting the ligand in multimeric form is a topic of general interest. Thus dimerization of single-chain bradykinin antagonist peptides has previously been shown to be beneficial in terms of potency and duration of action. While crosslinking polypeptides at terminal positions using suitable dicarboxylic acids and diamines is comparatively straightforward synthetically, internal dimerizations are usually achieved through oxidation or double S-alkylations of cysteine residues, resulting in metabolically unfavourable disulphide and thioether cross-links. Using suitably modified standard solid-phase peptide synthesis protocols, dimeric bradykinin antagonist peptides [H-(d-Arg)-Arg-Pro-Hyp-Gly-Phe]2-X-[(d-Phe)-Leu-Arg-OH]2 were synthesized where X corresponds to a l,l-2,7-diaminosuberic or l,l-2,9-diaminosebacic acid residue, respectively. The biological activity of these peptides was comparable to that of conventional dimeric bradykinin antagonists cross-linked through cystine or bis(succinimido)alkyl bridges. © 1998 European Peptide Society and John Wiley & Sons, Ltd.
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  • 78
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    Journal of Peptide Science 4 (1998), S. 300-304 
    ISSN: 1075-2617
    Keywords: Cryochemistry ; frozen organic solution ; peptide coupling ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The freezing effect on peptide coupling in organic solutions of different polarity has been investigated and compared with the results obtained in liquid phase. The model reaction of DCC-activated coupling of Boc-Ala-Phe-OH with H-Ala-OBut has been carried out in dioxane, dimethylsulfoxide and formamide, as well as in mixtures (90%/10%, v/v) of dioxane with acetonitrile, dimethylformamide, dimethylsulfoxide and formamide.The reactions have been traced and evaluated by RP-HPLC analysis. Freezing the reaction mixture resulted in all cases in a significant suppression of the N-dipeptidylurea side-product formation together with a slight decrease of tripeptide epimerization. The coupling yields and the side effects depended on the solvent, with the dioxane and dioxane/acetonitrile mixture produced the best results. The role of freezing and solvent in the improved results is discussed. © 1998 European Peptide Society and John Wiley & Sons, Ltd.
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  • 79
    ISSN: 1075-2617
    Keywords: Coloured neurotensin analogues ; coloured peptides ; coloured peptide libraries ; peptide labelling with chromophores ; peptide synthesis on coloured support ; solubilizing tags ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several methods were developed for the solid-phase synthesis (SPPS) of coloured peptides and peptide libraries. At first a bifunctional red compound, 4-(4-(N-ethyl-N-(3-(tert-butyloxycarbonyl)aminopropyl)amino)phenylazo)benzoic acid (Boc-EPAB), was coupled with chloromethyl resin to obtain a new solid support suitable for SPPS using Boc chemistry. Peptides synthesized on this coloured resin had the chromophore at their C-termini. N-terminally coloured peptides were synthesized on a traditional solid support, coupled with chromophoric carboxylic acid before cleavage. A model pentapeptide, Phe-Ala-Val-Leu-Gly, and its ten derivatives were synthesized and their properties studied. It was found that the presence of chromophores decreases the water solubility of peptides. However, insertion of solubilizing tags (penta-lysine sequences or polyoxyethyl chains) into the molecule of any coloured derivative resulted in enhancement of the solubility. The RP-HPLC hydrophobicity indexes (ϕ0) of the coloured peptides were also determined because ϕ0 values are closely related to their water solubility. A coloured pentapeptide library was synthesized using the portioning-mixing method. Each component of this library contained the red azo dye (EPAB) and the penta-lysine tag. Before the last coupling step the samples were not mixed. All of the 19 sub-libraries obtained after cleavage were readily soluble in water, giving intense red solutions.The effect of chromophore (EPAB) and/or penta-lysine solubilizing tag on the biological activity was also studied. Potencies of the bovine neurotensin 8-13 fragment and its different coloured and penta-lysine derivatives were compared in isolated longitudinal muscle strips of guinea pig ileum. It was shown that the hexapeptide with penta-lysine tag had almost the same activity as the 8-13 fragment itself. The activity of the EPAB-derivative was found to be rather low. However, the presence of the solubilizing tag in the coloured hexapeptide compensated the negative effect of the chromophore. © 1998 European Peptide Society and John Wiley & Sons, Ltd.
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  • 80
    ISSN: 0884-3996
    Keywords: adenyl compounds ; DNA ; chemiluminescence ; glyoxal derivatives ; heteropoly acid ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A chemiluminescence (CL) determination of adenyl compounds is described. CL derivatization of adenyl compounds with methylglyoxal dimethyl acetal was performed in the presence of tungstosilicic acid and propan-2-ol. CL from adenyl compounds was produced by hydrogen peroxide and L-cysteine ethyl ester in DMF and water. The proposed method is highly sensitive and specific to compounds containing adenine. Adenine was determined in the range 1.0 × 10-3 -5.0 × 10-8 M with the detection limit of 3.0 × 10-8 M (150 fmol per assay). The method was applied to the determination of DNA and detection limits of a few nanograms of DNA achieved. © 1998 John Wiley & Sons, Ltd.
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  • 81
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    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 31-40 
    ISSN: 0884-3996
    Keywords: chemiluminescence ; 10-methyl-N-(sulphonyl)-9-acridinium carboxamide ; liquid chromatography ; derivatization ; carboxylic acids ; ibuprofen ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The synthesis of a new acridinium sulphonylamide label for the liquid chromatographic determination of carboxylic acids is described. The label 10-methyl-N-(p-tolyl)-N-(p-iodoacetamidobenzenesulphonyl)-9-acridinium carboxamide iodide is synthesized from 9-acridinecarboxylic acid by a seven-step reaction. Ibuprofen, used as test compound, is coupled to the reactive iodoacetamide group of the label by means of an alkylation reaction in dry acetonitrile for 20 min at 50°C in the presence of 18-crown-6 and potassium carbonate as base catalyst. The reaction mixture is injected into a liquid chromatographic system with chemiluminescence detection. Separation is performed on a Zorbax C18 column with acetonitrile-water-tetrahydrofuran (39:57:4, v/v/v) containing 10 mmol/L TBABr and 0.035% H2O2 as the mobile phase at a flow rate of 1.0 ml/min. Chemiluminescence detection is achieved by the post-column addition of 200 mmol/L potassium hydroxide dissolved in methanol-water (1:1, v/v) at a flow rate of 20 μL/min. The detection limit (S/N = 3) of derivatized ibuprofen is 60 pg (3 pg injected). © 1998 John Wiley & Sons, Ltd.
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  • 82
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    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 75-84 
    ISSN: 0884-3996
    Keywords: luminol ; enhanced chemiluminescence ; phenol ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Systematic studies on phenol derivatives facilitates an explanation of the enhancement or inhibition of the luminol-H2O2-horseradish peroxidase system chemiluminescence. Factors that govern the enhancement are the one-electron reduction potentials of the phenoxy radicals (PhO•/PhOH) vs. luminol radicals (L•/LH-) and the reaction rates of the phenol derivatives with the compounds of horseradish peroxidase (HRP-I and HRP-II). Only compounds with radicals with a similar or greater reduction potential than luminol at pH 8.5 (0.8 V) can act as enhancers. Radicals with reduction potentials lower than luminol behave in a different way, because they destroy luminol radicals and inhibit chemiluminescence. The relations between the reduction potential, reaction rates and the Hammett constant of the substituent in a phenol suggest that 4-substituted phenols with Hammett constants (σ) for their substituents similar or greater than 0.20 are enhancers of the luminol-H2O2-horseradish peroxidase chemiluminescence. In contrast, those phenols substituted in position 4 for substituents with Hammett constants (σ) lower than 0.20 are inhibitors of chemiluminescence. On the basis of these studies, the structure of possible new enhancers was predicted. © 1998 John Wiley & Sons, Ltd.
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  • 83
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    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 13-19 
    ISSN: 0884-3996
    Keywords: cereal products ; auto-oxidation ; hydration ; chemiluminescence spectra ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Spectra of ultraweak chemiluminescence (CL) accompanying auto-oxidation and hydration of cereal products have been measured using single photon counting and cut-off filters. The spectra cover the 380-880 nm spectral range with maxima centred around 600 nm. Analytically pure air-dried carbohydrates like agar, cellulose and nitrocellulose give emission too weak for spectral measurements. The emission from water pure carbohydrates is on average 4-12 times higher and emission spectra are similar to those from cereal products. The effect of free radical scavengers, SOD and O*2 (1Δg)-quenchers on CL spectra indicates a contribution of radical reactions with the participation of excited carbonyls, O2- and excited molecular oxygen dimoles. Moreover, possible mechanisms of chemi-excitation due to a cooperative H-bond formation during the hydration of carbohydrates and/or recombination of trapped radicals and electron-holes are discussed. It is also postulated that the excitation energy transfer to natural sensitizers occuring in cereal products may account for non-specific broad spectra and differences in the intensity of CL. © 1998 John Wiley & Sons, Ltd.
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  • 84
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    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 41-59 
    ISSN: 0884-3996
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The journal provides comprehensive literature searches which will be published in most issues.
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  • 85
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    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 69-74 
    ISSN: 0884-3996
    Keywords: dioxetanes ; thermolysis ; quantum chemistry ; excited states ; chemiluminescence ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Energy diagrams, changes of geometry and bond orders were calculated semi-empirically for the thermolysis of 1,2-dioxetane. Stretching of the O-O bond, then of the C-C bond and distortion of the whole quadrangular structure make major, but different, contributions to the reaction coordinate on the path to formaldehyde. The activation barrier represents a vast region where the gaps between the ground and excited states are small, and this favours horizontal radiationless transitions leading to the excitation of a product. The results show that semi-empirical calculations may help to provide better insight into the nature and mechanism of the chemiluminescence excitation. © 1998 John Wiley & Sons, Ltd.
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  • 86
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    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 91-99 
    ISSN: 0884-3996
    Keywords: chemiluminescence ; platelet-activating factor ; alveolar macrophages ; neutrophils ; sulphite ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Alveolar macrophages (AM) were studied for their capability to release mediators involved in modulation of neutrophil (PMN) functions. Initial responses were induced by sulphite. Supernatants obtained from canine, human and rat AM pre-treated with sulphite in concentrations of 0.1-2 mmol/L enhanced the respiratory burst of canine, human and rat PMN, measured by lucigenin-dependent chemiluminescence (CL). This PMN-stimulating activity exhibited platelet-activating factor (PAF)-like properties, as indicated by desensitization of the PAF receptor, inhibition with PAF antagonists WEB 2086 and CV 3988, and the kinetic CL response like PAF after chloroform extraction of supernatants inhibitable by PAF antagonist CV 3988. These results indicate that AM are triggered by sulphite to release mediators that activate the respiratory burst of PMN, primarily via the PAF receptor. © 1998 John Wiley & Sons, Ltd.
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  • 87
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    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 117-123 
    ISSN: 0884-3996
    Keywords: electrochemiluminescence ; metals ; melanins ; luminol ; binding ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Electrochemiluminescence (ECL) studies of the chemiluminescent (CL) polymer diazoluminomelanin (DALM) biosynthesized in nitrate reductase transfected Escherichia coli JM109 bacteria revealed noteworthy anodic ECL and even more intense cathodic ECL. Bacterial DALM (BD) ECL was also assessed in the presence of 100 ppm of 33 different metal and non-metal ions which revealed specific anodic, but not cathodic, enhancements of BD ECL with Ag+, Hg2+ and Ru3+. The precursors and intermediate polymers which comprise DALM, such as luminol, 3-amino-L-tyrosine (3-AT), aminomelanin (AM) and diazomelanin (DM) were screened for ECL enhancement against the same set of elemental ions. Significant anodic ECL enhancements were observed for luminol with Hg2+ in the presence of tripropylamine (TPA), but not for any other DALM component in combination with other elemental ions, either anodically or cathodically. Comparison of BD with luminol in the presence and absence of TPA and Hg2+ revealed very different ECL activity patterns and suggested different mechanisms for BD and luminol ECL. © 1998 John Wiley & Sons, Ltd.
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  • 88
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    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 147-156 
    ISSN: 0884-3996
    Keywords: luminous bacteria ; identification ; cluster analysis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Differentiation of marine luminous bacteria using Biolog GN plate combined with API 20e or the BBL Crystal ID plate inoculated with cell suspensions in artifical seawater was accomplished by comparison to type species using cluster analysis. Inoculum density affected the results from Biolog GN plates, but had less of an effect on the reactions obtained from API 20e strip or BBL Crystal ID plate. In a few cases, combination of the Biolog GN traits along with either the API 20e or Crystal ID traits was necessary to differentiate some marine luminous bacteria. © 1998 John Wiley & Sons, Ltd.
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  • 89
    ISSN: 0884-3996
    Keywords: immunoassay ; nucleic acid assay ; PCR ; LCR ; chemiluminescence ; bioluminescence ; food testing ; pharmaceutical testing ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The sensitivity, speed and convenience of chemiluminescent (CL) and bioluminescent (BL) immunoassays and probe assays have led to a diverse range of applications for these technologies, mainly in the clinical laboratory. These methods are now being explored by the food and pharmaceutical industries. Demanding detection limits and the complexity of sample preparation for food and pharmaceutical analyses present daunting challenges for the analyst. Immunoassay and nucleic acid amplification technologies have been applied to food testing, but these have mostly favoured non-luminescent endpoints. Food assays with CL or BL endpoints are now emerging, e.g., Clostridium botulinum type A detection using a CL immunosorbent assay; Salmonella and Zygosaccharomyces detection using a combination of PCR and CL detection. The analytical challenges posed by the pharmaceutical industry include testing for contaminants in raw materials and drug products, and drug discovery. The sensitivity and rapid signal acquisition characteristics of CL and BL are advantageous for the high throughput, massively parallel testing of micro-sized samples demanded in drug discovery. Current progress and the prospects for CL and BL immunoassay and nucleic acid technologies in this and other pharmaceutical and food applications is reviewed. © 1998 John Wiley & Sons, Ltd.
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  • 90
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    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 267-271 
    ISSN: 0884-3996
    Keywords: chemiluminescence ; leukocyte ; horseradish peroxidase ; luminol ; light emission ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The chemiluminescence (CL) technique with scavengers for superoxide anion (superoxide dismutase) and hydrogen peroxide (catalase) was used to characterize the generation of reactive oxygen species (ROS) inside and outside the human neutrophil after stimulation with both soluble (formyl-methionyl-leucyl-phenylalanine, FMLP) and particulate (urate crystals, zymosan, oxidized LDL) stimuli. Depending on the stimulus used, ROS generation differed in composition and absolute amounts. The ratio between extracellularly and intracellularly produced ROS ranged from 0.3 (zymosan) to 4.2 (FMLP). While enhancing substantially FMLP-stimulated CL, horseradish peroxidase inhibited CL induced by particulate stimuli by 40-80%. Furthermore, an azide-insensitive and therefore peroxidase-independent part of CL was found in FMLP-, LDL- and zymosan-stimulated cells. The results indicate that different agonists may lead through distinct chemical pathways to neutrophil luminol-amplified light generation. © 1998 John Wiley & Sons, Ltd.
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  • 91
    ISSN: 0884-3996
    Keywords: factor XIIIa ; transglutaminase ; aminobutyl-N-ethyl-isoluminol ; chemiluminescent assay ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A novel and sensitive chemiluminescent assay is described to quantitate the acyl transfer activities of blood coagulation factor XIIIa or liver transglutaminase using aminobutyl-N-ethyl-isoluminol as acyl acceptor and N,N′-dimethylcasein, human plasma fibrinogen or fibronectin as acyl donors. The method involved covalently linking aminobutyl-N-ethyl-isoluminol through its free amino group with the γ-carboxamide of protein-bound glutamine resulting in an isopeptide bond; a reaction catalysed by both transglutaminase and factor XIIIa. The protein-bound aminobutyl-N-ethyl-isoluminol was separated from non-conjugated amine by precipitation with trichloroacetic acid. The protein-amine conjugate was dissolved in 500 mmol/L NaOH, oxidized using 15 mmol/L ammonium persulphate and light emission quantitated using a luminometer. Optimal conditions were established to detect factor XIIIa and transglutaminase activities with the chemiluminescent assay. Specificity was demonstrated by lack of activity in the presence of ethylenediamine tetra-acetic acid or unactivated factor XIII, or boiled enzymes, and by competitive inhibition with putrescine and 5′-(biotinamido) pentylamine. The enzymatic and kinetic properties of factor XIIIa and transglutaminase in utilizing aminobutyl-N-ethyl-isoluminol as an acyl acceptor substrate were comprehensively documented. The reaction could be carried out in either a purified system or a complex plasma or cell lysates milieu. The assay is sensitive, specific, and eliminates a need for radioactive reagents. The assay could be used to photolabel reactive glutamines in substrates. The assay could also be adapted to a variety of solid- and solution-phase formats and is amenable to X-ray film and/or light photography imaging. © 1998 John Wiley & Sons, Ltd.
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  • 92
    ISSN: 0730-2312
    Keywords: HMG-CoA ; MVA ; HPLC ; dolichol-like lipids ; DNA synthesis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Substantial evidence has suggested that a nonsterol product of mevalonic acid (MVA) is essential for the initiation of DNA synthesis in mammalian cells. Several possible isoprenoid candidates have been suggested, but the identity of this compound still remains unknown. In this study we have isolated and purified MVA products from SV40-transformed human fibroblasts and identified fractions with a growth-stimulatory effect. The cells were labelled with [14C]MVA in the presence of inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase. After lipid extraction, the [14C]MVA-labelled lipids were subjected to high performance liquid chromatography and size-exclusion chromatography, and the effect of the fractionated eluate on the DNA synthesis of arrested MVA-depleted target cells was tested. Thereby we found a fraction of [14C]MVA-labelled lipids with a substantial stimulatory effect on DNA synthesis. The chromatographic behavior suggested that the growth-stimulating fractions contained dolichol-20. This was confirmed by mass spectrometric analysis. Similar results were obtained when lipids from hepatocellular carcinoma cells and a sample from breast tumor were isolated and analyzed by the same procedure. The mechanisms by which these compounds induce DNA synthesis are unknown. Recent data obtained in our laboratory have provided evidence that dolichyl groups are covalently linked to tumor cell proteins, which implicates a new biological function for long-chain polyisoprenoid alcohols (Hjertman et al. [1997] FEBS Lett 416:235-238). In this study we demonstrate that tumor cells containing dolichol-like growth-stimulatory lipids also contained dolichylated proteins. This raises the question whether the growth-stimulatory dolichol-like lipids serve as substrates for the dolichylation reaction. J. Cell. Biochem. 71:502-514, 1998. © 1998 Wiley-Liss, Inc.
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  • 93
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    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 125-130 
    ISSN: 0884-3996
    Keywords: chemiluminescence ; electrocatalysed ; luminol ; oxygen ; glucose ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Dissolved elemental oxygen is determined in a flowing aqueous stream using glucose oxidase to catalyse the reaction between D-glucose and O2 to produce hydrogen peroxide. The levels of the resulting H2O2 are detected and quantified by luminol chemiluminescence using in-line solid phase media for pH adjustment of the reagent stream and for controlled release of the luminophore. The reaction is initiated by electrochemical catalysis. By the use of excess D-glucose in the reagent flow stream, the intensity of chemiluminescence is rendered proportional only to fluctuations in the dissolved O2 concentration. The methodology provides a means for the detection of aqueous O2 in the range 0-10 mg/L. © 1998 John Wiley & Sons, Ltd.
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  • 94
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    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 195-200 
    ISSN: 0884-3996
    Keywords: chemiluminescence ; esterase ; monocytes ; horseradish peroxidase ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Esterase from monocytes promotes the hydrolysis of 2-methyl-1-propenylbenzoate (MPB) yielding 2-methyl-1-propenol, which is oxidized by horseradish peroxidase/H2O2 producing triplet acetone. The chemiluminescence of this reaction can be enhanced by the addition of 9,10-dibromoanthracene-2-sulphonate. The non-specific esterase present in monocytes is responsible for MPB hydrolysis, since (a) the chemiluminescence of the reaction was inhibited by fluoride, and (b) cells that do not contain a significant amount of non-specific esterases, e.g. lymphocytes and neutrophils, did not trigger light emission. The analytical application of this reaction is considered. © 1998 John Wiley & Sons, Ltd.
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  • 95
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    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 113-113 
    ISSN: 0884-3996
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: No Abstract
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  • 96
    Electronic Resource
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    New York : Wiley-Blackwell
    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 101-105 
    ISSN: 0884-3996
    Keywords: photographic detection ; oligodeoxynucleotide ; peroxyoxalate chemiluminescence ; membrane ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: The preparation of a fluorescent labelled oligonucleotide and its photographic detection by peroxyoxalate chemiluminescence (PO-CL) are described. Fluorescent labelling of an oligonucleotide (15-mer) was performed with naphthalene-2,3-dicarboxaldehyde to give an N-substituted 1-cyanobenz[f]isoindole (CBI) derivative (CBI-15-mer). For the photographic detection of CBI-15-mer, the bis(2,6-difluorophenyl) oxalate (DFPO)-dimethyl phthalate (DMP) system was selected to obtain a long-lived CL emission. After optimizing the conditions for the CL reaction, the system was applied to the photographic detection, and as little as 250 fmol per spot of CBI-15-mer on a membrane were detected as a visible spot with an instant photographic film. © 1998 John Wiley & Sons, Ltd.
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  • 97
    Electronic Resource
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    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 107-111 
    ISSN: 0884-3996
    Keywords: chemiluminescent immunoassay ; acridinium ester ; fish ; salmon ; growth hormone ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: An immune complex transfer two-site chemiluminescent immunoassay (CLIA) for salmon growth hormone (GH) was developed to measure serum GH in alevin chum salmon (Oncorhynchus keta) using a chemiluminescent acridinium ester as a label. The immune complex transfer method dramatically reduced non-specifically bound of acridinium ester-labelled antibody without a decrease in the specific binding. Consequently, we could detect lower levels of GH than achieved previously in a two-site CLIA for salmon GH. The detection limit of the assay was 7.8 fg/mL and the standard curve was linear up to 250 fg/mL. Coefficients of variation were 2.2-7.7% within-assay and 5.3-9.1% between-assay. We have developed a highly sensitive and reproducible GH method and applied it to measurement of GH in alevin chum salmon. © 1998 John Wiley & Sons, Ltd.
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  • 98
    ISSN: 0884-3996
    Keywords: chemiluminescence ; flow injection ; isoniazid ; solid-phase reactors ; pharmaceutical analysis ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A flow injection procedure for the indirect chemiluminescent determination of isoniazid is proposed. The method is performed in a flow-injection manifold provided with a solid-phase reactor. The reactor was made from manganese dioxide physically entrapped by polymerization; the redox reaction isoniazid-manganese dioxide released Mn(II) which was monitored through its inhibitory effect on the reaction between luminol and hydrogen peroxide in presence of potassium hexacyanoferrate(III). The procedure resulted in a linear calibration graph over the range 5-15 mg/L of isoniazid with a sample throughput of 43 samples/h. The influence of foreign compounds was studied and the method was applied to determination of the drug in a pharmaceutical formulation. © 1998 John Wiley & Sons, Ltd.
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  • 99
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    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 157-184 
    ISSN: 0884-3996
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
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  • 100
    Electronic Resource
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    Journal of Bioluminescence and Chemiluminescence 13 (1998), S. 263-266 
    ISSN: 0884-3996
    Keywords: glutathione ; bioluminescent assay ; microassay ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A novel technique has been developed for semiquantitative detection of glutathione (GSH) in small volumes of liquid samples. GSH is detected via enzymatic linkage to the NADP/NADPH + H+ redox system through glutathione reductase. Accumulated NADPH is measured via the bioluminescent FMN oxidoreductase bacterial luciferase reaction. A linear correlation is obtained between bioluminescence intensity of the luciferase reaction and the GSH content of the liquid sample. Possible applications of this procedure are discussed. © 1998 John Wiley & Sons, Ltd.
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