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  • HPLC
  • Springer  (87)
  • American Chemical Society
  • Elsevier
  • Nature Publishing Group
  • 1990-1994  (87)
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Keywords
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  • Springer  (87)
  • American Chemical Society
  • Elsevier
  • Nature Publishing Group
  • Wiley-Blackwell  (69)
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Ribonucleosides as minor milk constituents (1991)
    Springer
    European journal of nutrition 30 (1991), S. 138-152 
    Details
    ISSN: 1436-6215
    Keywords: Ribonucleosides ; RNAcatabolism ; bovinemilk ; goatmilk ; colostral phase ; lactation period ; minor milkconstituents ; buttersera ; intrinsicindicators ; differentiation ofbutter types ; HPLC ; Ribonucleoside ; RNA-Katabolismus ; Kuhmilch ; Ziegenmilch ; Kolostralphase ; Laktationsperiode ; minore Milchinhaltsstoffe ; Butterseren ; intrinsische Indikatoren ; Differenzierung von Buttersorten ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung Ribonucleoside gehören zu den minoren Inhaltsstoffen der Milch und zeigen ein tierartentypisches Ribonucleosidmuster. Neben den unmodifizierten Komponenten Adenosin, Cytidin, Guanosin, Inosin und Uridin wurden modifizierte Verbindungen wie N1-Methyladenosin und N6-Carbamoylthreonyladenosin, die aus dem Transfer RNA-Katabolismus stammen, in Einzel- und Sammelmilchen einer kleinen Herde Deutscher Schwarzbunter nachgewiesen und quantitativ über eine gesamte Laktation bestimmt. Die Verlaufsstudie hat gezeigt, daß die Konzentrationsspiegel dieser minoren Komponenten mit Ausnahme der Kolostralphase über die gesamte Laktationsperiode nur einer geringen Schwankungsbreite unterliegen. Ribonucleosidmuster sind deshalb zur Kennzeichnung von Milchen verschiedener Herkunft und Verarbeitung geeignet. Beispielhaft wurden deshalb Ribonucleoside im Verlaufe des Butterungsprozesses bilanziert und gezeigt, daß diesen minoren Komponenten „finger-print“-Eigenschaften zukommen, die zur Differenzierung der von der Butterverordnung definierten drei Buttersorten geeignet sind.
    Notes: Summary Ribonucleosides are minor milk constituents and show a typical pattern which is assumed to be species-specific. As well as the unmodified components adenosine, cytidine, guanosine, inosine, and uridine, modified compounds such as N1-methyladenosine and N6-carbamoylthreonyladenosine — products of the transfer RNA catabolism — have been identified and quantified in individual and bulk herd (race: German black pied) milk samples throughout a whole lactation period. The results of our longitudinal study have shown that — with the exception of the colostral phase — the levels of these minor constituents vary only slightly throughout lactation. These findings imply that ribonucleosides are useful for characterizing milk of different species and technological treatment. Ribonucleosides were determined and balanced, for example, in the course of the churning process, showing that the pattern of these minor milk constituents is useful as a “fingerprint” that allows differentiation between the three butter types defined in the German Federal Butter Ordinance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01610069
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  • 2
    Electronic Resource
    Electronic Resource
    Elektronen-Spin-Resonanz-Messungen an Trockenfrüchten (1994)
    Springer
    European journal of nutrition 33 (1994), S. 258-266 
    Details
    ISSN: 1436-6215
    Keywords: ESR ; HPLC ; Lebensmittelbestrahlung ; Trockenfrüchte ; Kohlenhydrate ; ESR ; HPLC ; food irradiation ; dried fruits ; sugars
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary While in a previous work the ESR spectroscopic detection of irradiated dried fruits was reported, in this paper liquid chromatographic determination of the carbohydrate fraction of these fruits is introduced and connected with the ESR results. After irradiation of dried fruits three different types of ESR spectra are observed. In most cases the dried fruits can be attached to these various types by means of their sugar composition. It was also found that the ESR spectra observed for sucrose-rich fruits are very similar to that of pure sucrose. The structure of the ESR spectra can change with storage. Probably, radical rearrangement reactions in the samples are responsible for these changes.
    Notes: Zusammenfassung Nachdem in einer früheren Arbeit der ESR-spektroskopische Nachweis von strahlenbehandelten Trockenfrüchten besprochen wurde, wird in diesem Bericht die flüssigchromatographische Bestimmung der Kohlenhydratfraktion dieser Früchte vorgestellt und ein Zusammenhang zwischen der Zuckerzusammensetzung und den ESR-Signalstrukturen nachgewiesen. Die bei der Bestrahlung von Trockenfrüchten beobachteten ESR-Spektren lassen sich in 3 Typen unterteilen. Die Zuordnung der Trockenfrüchte zu den einzelnen Typen anhand ihrer Kohlenhydratzusammensetzung gelingt in einer überwiegenden Zahl der untersuchten Proben. Weiterhin wird festgestellt, daß die beobachteten ESR-Signale in ihrem Habitus denen der reinen bestrahlten Mono- und Disaccharide ähnlich sind. Dies trifft besonders für saccharosereiche Früchte und Saccharose zu. Die Struktur der ESR-Spektren strahlenbehandelter Trockenfrüchte kann sich über einen längeren Zeitraum ändern. Für die Veränderung werden radikalische Umwandlungen in der Probenmatrix verantwortlich gemacht.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01614431
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  • 3
    Electronic Resource
    Electronic Resource
    A simple assay for fluorescent siderophores produced by Pseudomonas species and an efficient isolation of pseudobactin (1994)
    Springer
    BioMetals 7 (1994), S. 20-24 
    Details
    ISSN: 1572-8773
    Keywords: HPLC ; pseudobactin ; Pseudomonas fluorescens ; siderophores
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Several iron binding metabolites (siderophores) of Pseudomonas fluorescens B10 (JL-3133) have been detected using C18 reverse phase HPLC coupled with photodiode array detection methods. This analysis utilized a volatile mobile phase of 90% 20 mm NH4HCO3/10% MeOH, pH 6.5. It has been shown to be applicable to other P. fluorescens strains for the detection of related metabolites. Direct scale-up of the analytical HPLC conditions allowed for the efficient preparative isolation of pseudobactin, the principle siderophore produced by P. fluorescens B10 (JL-3133).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00205189
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  • 4
    Electronic Resource
    Electronic Resource
    HPLC separation of enterobactin and linear 2,3-dihydroxybenzoylserine derivatives: a study on mutants ofEscherichia coli defective in regulation (fur), esterase (fes) and transport (fepA) (1994)
    Springer
    BioMetals 7 (1994), S. 149-154 
    Details
    ISSN: 1572-8773
    Keywords: 2,3-dihydroxybenzoylserine ; enterobactin ; Escherichia coli ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Reversed-phase HPLC separation of enterobactin and its 2,3-dihydroxybenzoylserine derivatives was used for a comparative analysis of mutants of Escherichia coli, defective in the regulation of enterobactin biosynthesis (fur), enterobactin transport (fepA) and enterobactin esterase (fes). A complete separation of all 2,3-dihydroxybenzoylserine compounds was achieved: the monomer (DHBS), the linear dimer (DHBS)2 and trimer (DHBS)3, the cyclic trimer, enterobactin, as well as 2,3-dihydroxybenzoic acid. The production of all these compounds was followed after ethylacetate extraction from acidified culture fluids. Enterobactin was found to be the predominant product in all mutant strains. The mutant strains behaved differently with regard to the breakdown products. All degradation products, such as DHBS, (DHBS)2 and (DHBS)3, were detected in the overproducing fur mutant where both transport and esterase are still functioning, while only the monomer, DHBS, was detected in the fepA mutant and no degradation was found in the esterase-deficient fes mutant. From the pattern of breakdown products it may be inferred that the esterase acts in two different ways, depending on whether transport is functioning or not. Thus, esterolytic cleavage of ferric enterobactin after entering the cells results in a mixture of all three hydrolysis products, i.e. DHBS, (DHBS)2 and (DHBS)3, while cleavage of iron-free enterobactin subsequent to its biosynthesis yields only the monomer. Thus, the results of quantitative HPLC analysis of enterobactin and its breakdown products show that different enterobactin esterase products arise, depending on whether iron is bound to enterobactin or not.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00140485
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  • 5
    Electronic Resource
    Electronic Resource
    Hydrolysis of low-molecular-weight soil peptides by immobilized proteases in column and batch reaction systems (1990)
    Springer
    Biology and fertility of soils 9 (1990), S. 335-340 
    Details
    ISSN: 1432-0789
    Keywords: Amino acids ; HPLC ; Immobilized protease ; Organic matter fractions ; Peptides ; Soil nitrogen ; Soil enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Organic matter was extracted from three soils, a cultivated Berwick sandy loam, a cultivated Franklin loamy sand, and an uncultivated Cumberland silty loam. Gel-permeation chromatography was used to separate organic matter extracts into high- (HMW) and low-molecular-weight (LMW) fractions. Reversed-phase high performance liquid chromatography was used to separate and collect the LMW peptide fractions. Peptide samples were hydrolyzed with immobilized proteases attached to beaded agarose and carboxymethyl cellulose in column and batch reaction systems. The chromatograms suggested that peptides are bound to common soil components. The amino acids released in the greatest percentages were relatively non-polar. Large percentages of serine, glycine, alanine, threonine, and valine were observed in the LMW soil peptides. Little aspartic acid, asparagine, glutamic acid, glutamine, arginine, and no histidine was detected in the LMW soil peptides. The soil peptides released different amino acid percentages and quantities when hydrolyzed by immobilized proteases attached to different supports. The quanitities of amino acids released by batch hydrolysis differed from those obtained with column hydrolysis. Greater quantities of amino acids were released (by both types of immobilized protease) from the LMW peptide hydrolysates of the two cultivated soils than from the uncultivated soil.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00634111
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  • 6
    Electronic Resource
    Electronic Resource
    Opsin localization and chromophore retinoids identified within the basal brain of the lizard Anolis carolinensis (1993)
    Springer
    Journal of comparative physiology 172 (1993), S. 33-45 
    Details
    ISSN: 1432-1351
    Keywords: Photoreception ; Extraretinal Photoreceptor ; Chromophore ; Opsin ; Reptile ; Immunocytochemistry ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Since the beginning of this century evidence has accumulated which demonstrates that non-mammalian vertebrates possess photoreceptors situated deep within the brain. While many attempts have been made to localize these sensory cells, studies have either failed or been inconclusive. In this report we have used several experimental approaches to localize the deep brain photoreceptors of the lizard Anolis carolinensis. Using 3 antibodies that bind vertebrate cone opsins, we have immunolabelled cerebrospinal fluid (CSF)-contacting neurons located at the ventricular border within the nucleus ventromedialis of the septum. Western blot analysis indicates that these antibodies recognized a single 40 kD protein in ocular, anterior brain, and pineal extracts. Immunoblots of rodent brain did not show a similar protein band. We have also identified specific retinoids associated with phototransduction (11-cis and all-trans-3,4-didehydroretinaldehyde) within anterior brain extracts. This combined data provides the most detailed analysis of deep brain photoreceptors in any vertebrate. Consequently, we feel Anolis provides an excellent model to study this unexplored sensory system of the vertebrates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00214713
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  • 7
    Electronic Resource
    Electronic Resource
    Quantitation of carbohydrate sweeteners and organic acids in human oral fluid using HPLC analysis (1992)
    Springer
    European journal of nutrition 31 (1992), S. 147-154 
    Details
    ISSN: 1436-6215
    Keywords: Sugars ; carbohydrates ; lacticacid ; oralfluid ; HPLC ; glucose ; sucrose ; Zucker ; Kohlenhydrate ; Milchsäure ; Speichel ; HPLC-Analyse ; Glukose ; Saccharose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung Eine empfindliche HPLC-Methode wurde für die qualitative und quantitative Analyse von Kohlehydraten und organischen Säuren in Mundflüssigkeiten (Speichel und Zahnplaque) entwickelt. Für die Trennung dieser Verbindungen wurde eine Aminex HPX-87H (Bio-Rad) Chromatographie-Säule verwendet. Alle Komponenten des HPLC-Systems waren mit Edelstahl-Kapillaren verbunden. Die isokratische Elution beider Verbindungs-Klassen erfolgte mit 0,01 n Schwefelsäure. Alle Verbindungen wurden mit einem RI-(Refraktion-Index-) Detektor gemessen. Die Ergebnisse wurden mit einem PC-gestütztem Auswertesystem automatisch gesammelt und integriert. Die zeitbedingte Abnahme der Konzentration von Kohlehydraten im Munde einerseits und die Produktion von organischen Säuren durch Bakterien der Mundhöhle andererseits können mit dieser empfindlichen HPLC-Methode bis zu einer Genauigkeit von 0,1 µg Substanz per Analyse (80 µl) bestimmt werden.
    Notes: Summary A sensitive high performance liquid chromatography (HPLC) assay was developed for the qualitative and quantitative determination of carbohydrate sweeteners and organic acids in oral fluid. To separate these compounds, an ion-moderated partition resin HPLC column (Aminex HPX-87H) was used. All components of the HPLC system were interconnected using stainless steel capillary tubing. Isocratic elution with 0.01 N sulfuric acid provided the profile of both compound classes. The compounds were detected using a refractive index detector. The method employed computerized data collection and integration (Omega-2 system) with a detection sensitivity of 0.1 µg compound per HPLC assay (80 µl). This method is useful in caries research, because it detects minute amounts of sugars and organic acids in oral fluid during clearance studies of various foods in the mouth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01623073
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  • 8
    Electronic Resource
    Electronic Resource
    Determination of nifedipine in human plasma by high performance liquid chromatography using column-switching technique (1994)
    Springer
    Microchimica acta 113 (1994), S. 171-178 
    Details
    ISSN: 1436-5073
    Keywords: nifedipine ; HPLC ; column switching technique ; electrochemical detection ; validation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A highly sensitive reversed-phase HPLC method has been developed for the determination of nifedipine in human plasma with electrochemical detection. A liquid-liquid extraction procedure is used in sample preparation with an average extraction recovery of 75%. Removing the highly lipophilic plasma components using a special column switching technique reduced the duration of the HPLC measurement from 30 to 9 min. The method is applicable for the pharmacokinetic characterization and bioavailability study of a sustained-release (retard) formulation of nifedipine and for human drug monitoring as it is indicated by the validation of the analysis method. The assay gave a linear response over the concentration range 2.5–50 ng/ml. All the validation parameters are within the internationally required limits.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01243609
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  • 9
    Electronic Resource
    Electronic Resource
    Speciation of organic and inorganic arsenic by HPLC-HG-ICP (1992)
    Springer
    Microchimica acta 109 (1992), S. 39-45 
    Details
    ISSN: 1436-5073
    Keywords: arsenic speciation ; HPLC ; hydride generation ; ICP-AES ; hyphenated techniques ; As(III) ; As(V) ; MMA ; DMA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract This paper deals with the application of high performance liquid chromatography (HPLC), hydride generation (HG) and inductively coupled plasma atomic emission spectrometry (ICP) to determine four species of arsenic: As(III), As(V), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA). The coupling conditions of HPLC-HG-ICP are given. Two anionic exchange columns (Nucleosil-5SB and Hamilton PRP X-100) are tested and the separation conditions optimized. Two acids (H2SO4 and HCl at different concentrations) are tested to obtain the hydrides. The proposed method is applied to determine four arsenic species in a synthetic matrix simulating a fish extract.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01243208
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  • 10
    Electronic Resource
    Electronic Resource
    Speciation studies for arsenic and mercury-applications and prospects (1992)
    Springer
    Microchimica acta 109 (1992), S. 107-109 
    Details
    ISSN: 1436-5073
    Keywords: speciation ; arsenic ; direct separation ; HPLC ; mercury gas chromatography ; anion exchange ; distillation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Methods are described for the speciation of arsenic and mercury in biological and environmental materials. For arsenic various methods were developed to distinguish between more or less toxic arsenic compounds and non-toxic compounds. For the determination of methylmercury a modification of the Westöö procedure was applied for higher contents as well as anion exchange down to levels below 0.1 μg/kg in solids and below 0.1 ng/1 in liquids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01243219
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  • 11
    Electronic Resource
    Electronic Resource
    Direct determination of tocopherols in paprika and paprika oleoresin by liquid chromatography (1992)
    Springer
    Microchimica acta 106 (1992), S. 293-302 
    Details
    ISSN: 1436-5073
    Keywords: HPLC ; tocopherols ; paprika ; paprika oleoresin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A method for the determination of tocopherols and tocopherol esters, quantified as tocopherol acetate, in paprika and paprika oleoresin is reported. Paprika samples were extracted with ethyl acetate and aliquots of the extracts were directly injected into a liquid chromatograph. Reverse phase high-performance liquid chromatography with spectrophotometric detection at 280 nm was used. Gradient elution was applied, allowing the determination of tocopherols and tocopherol esters in the presence of carotenoids. The method does not need previous separation steps, so is useful for the routine determination of vitamin E in commercial samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01242102
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  • 12
    Electronic Resource
    Electronic Resource
    Expert systems for method development and validation in HPLC (1991)
    Springer
    Microchimica acta 104 (1991), S. 493-503 
    Details
    ISSN: 1436-5073
    Keywords: expert systems ; method development ; method validation ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract ESCA, Expert Systems Applied to Chemical Analysis, started its research in March 1987, with the aim of building prototype expert systems for HPLC method development. Results of this research have been published as the work has progressed. The project is now completed and this paper summarises some of the overall project conclusions. Seven different expert systems have been built which tackle problems throughout the process of method development, four stand-alone systems and three integrated systems. The object of ESCA was to evaluate the applicability of expert system technology to analytical chemistry and not all the systems were built for commercial uses. Many of the systems tackle problems specific to one or more of the partners and thus may not be useful outside this environment. However, the results of the work are still pertinent to analysts wishing to build their own systems. These results are described, however, the emphasis of the paper is on those systems developed for method validation. Method validation for HPLC is a complex task which requires many characteristics of the method to be tested, e.g. accuracy, precision, etc. The expert systems built within ESCA concern the validation of precision. Two systems were developed for repeatability testing and ruggedness testing. The method validation process can be divided into several discrete stages, these include: (1) The selection of the method feature to test, for instance which factors can influence the ruggedness of a method. (2) The definition of a test procedure, for instance an efficient statistical design. (3) The execution of experiments and the interpretation of results. (4) A diagnosis of any observed problem. This paper describes these two systems in some detail and summarises some of the results obtained from their evaluation. It concludes that expert systems can be useful in solving analytical problems and the integration of several expert systems can provide extremely powerful tools for the analyst.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01245534
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  • 13
    Electronic Resource
    Electronic Resource
    Identification and determination of organic acids in cultivation medium ofPenicillium vermiculatum dang (1994)
    Springer
    Monatshefte für Chemie 125 (1994), S. 707-711 
    Details
    ISSN: 1434-4475
    Keywords: Penicillium vermiculatum ; vermiculin ; decadienoic acids ; 2-methylsorbic acid ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung [2E,7E]-4,9-dioxo-2,7-decadiensäure, [2E,7E]-9-oxo-2,7-decadiensäure und [2Z,4E]-2-methyl-2,4-hexa-diensäure wurden aus dem Kultivierungsmedium vonPenicillium vermiculatum Dang isoliert. Die Anwesenheit von [2E,2′E,7S,7′E]-4,9-dioxo-7-(4′,9′-dioxo-2′,7′-decadienoyloxy)-2-decensäure wurde chromatographisch bestätigt, Im Filtrat vonP. vermiculatum wurden diese Säuren mittels HPLC analysiert.
    Notes: Summary [2E,7E]-4,9-dioxo-2,7-decadienoic, [2E,7E]-9-oxo-2,7-decadienoic and [2Z,4E]-2-methyl-2,4-hexadienoic acids were isolated from the filtrate ofPenicillium vermiculatum Dang. The presence of [2E,2′E,7S,7′E]-4,9-dioxo-7-(4′,9′-dioxo-2′,7′-decadienoyloxy)-2-decenoic acid was confirmed by chromatography. HPLC was used for the determination of these acids in the cultivation medium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01277630
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  • 14
    Electronic Resource
    Electronic Resource
    Immunochemical analysis of trichothecenes produced by various fusaria (1993)
    Springer
    Mycopathologia 121 (1993), S. 179-192 
    Details
    ISSN: 1573-0832
    Keywords: ELISA ; Fusaria ; HPLC ; Mycotoxins ; TLC ; Trichothecenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The production of type A trichothecene mycotoxins by 19 Fusaria, including 12Fusarium sporotrichioides, 4F. chlamydosporum and 3F. graminearum at 15°C and 25°C over a 35-day period was analyzed by ELISA using antibodies cross-reactive with most type A trichothecenes after conversion to T-2 tetraol tetraacetate. The toxin production peaked at 20–25 days of incubation with maximum yield between 4–6 mg type A trichothecene/ml of culture medium for 5F. sporotrichioides cultures and between 1 to 2 mg/ml for 6F. sporotrichioides cultures. OneF. sporotrichioides produced 700 µg type A trichothecenes/ml of culture medium. Detectable type A trichothecene was also found in the culture extracts ofF. chlamydosporum andF. graminearum, but the yield was very low (less than 100 µg/ml). Quantitative determination of individual trichothecenes was achieved by separation of different toxin in HPLC and followed by ELISA analysis. Eight to 10 immunoreactive peaks, corresponding to various type A trichothecenes, were detected in all the fungal extracts. T-2 tetraol (T-2-4ol), 4-acetyl-T-2 tetraol (4-Ac-T-2-4ol), neosolaniol (NEOS), diacetoxyscirpenol (DAS), HT-2 and T-2 toxin accounted for more than 85% of the total toxins. In general, low temperature was preferred for total type A trichothecene production. More T-2-4ol, 4-Ac-T-2-4ol, HT-2 and DAS were produced at 25°C. In contrast, more T-2 toxin and NEOS were produced at 15°C. Transformation of T-2 toxin and NEOS to polar metabolites such as T-2-4ol, 4-acetyl-T-2-4ol and HT-2 by various strains were observed at both temperatures after 25 days incubation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01104075
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  • 15
    Electronic Resource
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    A rapid HPLC assay for zearalenone in laboratory cultures ofFusarium graminearum (1993)
    Springer
    Mycopathologia 121 (1993), S. 27-32 
    Details
    ISSN: 1573-0832
    Keywords: Corn ; Fusarium graminearum ; HPLC ; Zearalenone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract A high pressure liquid chromatographic (HPLC) method to determine zearalenone in corn contaminated withFusarium graminearum is described. After extraction with methanol-water and solvent partition, samples were cleaned up by applying the extract to a disposable silica cartridge and by eluting the toxin with a mixture of hexane/dry ethyl ether (5/5). Separation was achieved by a reverse phase μBondapak C18 column followed by fluorescence detection using an excitation wavelength at 274 nm and an emission wavelength at 440 nm. Detection limit was about 5 ng. Recoveries ranging from 85.37 to 100.97%, in standard solutions range 30–0.5 µg/ml, were found.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01103351
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  • 16
    Electronic Resource
    Electronic Resource
    Chemotaxonomy of the genus Talaromyces (1990)
    Springer
    Antonie van Leeuwenhoek 57 (1990), S. 179-189 
    Details
    ISSN: 1572-9699
    Keywords: heat-resistant moulds ; chemotaxonomy ; HPLC ; TLC ; mycotoxins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Species of the ascomycetous genus Talaromyces have been examined for profiles of secondary metabolites on TLC. The greatest number of specific metabolites were produced on oatmeal-, malt extract- and yeast-extract sucrose agars. Profiles of intracellular secondary metabolites produced on oatmeal agar were specific for each species and provided a means of simple differentiation of the taxa. Examination of the most important species using high performence liquid chromatography (HPLC) allowed to solve some taxonomic problems. Known mycotoxins are produced by T. stipitatus (duclauxin, talaromycins, botryodiploidin), T. stipitatus chemotype II (emodin), T. panasenkoi (spiculisporic acid), T. trachyspermus (spiculisporic acid), T. trac macrosporus (duclauxin) and T. wortmannii (rugulosin). Wortmannin is produced by an atypical strain of T. flavus but not T. wortmannii. Several other secondary metabolites were discovered for the first time in the following species: Glauconic acid is produced by T. panasenkoi, T. ohiensis and T. trachyspermus; vermiculine by T. ohiensis; duclauxin by T. flavus var. macrosporus and the mitorubrins by T. flavus and T. udagawae. The profiles of secondary metabolites support the established taxonomy of the species based on morphology, showing the genetic stability of profiles of secondary metabolites in Talaromyces. Two new taxa are proposed: T. macrosporus comb. nov. (stat. anam. Penicillium macrosporum stat. nov.), and Penicillium vonarxii, sp. nov. for the anamorph of T. luteus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00403953
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    Does chlorophyllidea reduce reliability of chlorophylla measurements in marine coastal sediments? (1993)
    Springer
    Aquatic sciences 55 (1993), S. 19-30 
    Details
    ISSN: 1420-9055
    Keywords: chlorophylla ; chlorophyllidea ; pheopigments ; spectrophotometry ; HPLC ; marine sediments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pigment concentrations (chlorophylla, chlorophyllidea and pheopigmentsa) were measured by HPLC and spectrophotometry with acidification on 57 samples collected in different marine coastal sediments, containing autochthonous microphytes, and with various organic matter contents (plant detritus, biodeposits or hydrocarbons). Statistical analysis shows that the spectrophotometry with acidification, as compared to HPLC, gives reliable values for chlorophylla. Chlorophyllidea concentrations may be considered as negligible. Though spectrophotometric methods are sometimes questioned when applied to sediments they appear to give easy, quick and good estimates of Chla contents in benthic microphytes for hydrobiological studies in coastal areas.
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    URL: http://dx.doi.org/10.1007/BF00877256
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    Separation of phytoplanktonic pigments by HPLC for the study of phyto-zooplankton trophic relationships (1994)
    Springer
    Aquatic sciences 56 (1994), S. 29-39 
    Details
    ISSN: 1420-9055
    Keywords: Trophic relationships ; organic biomarkers ; herbivorous zooplankton ; phytoplanktonic pigments ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phyto-zooplankton trophic relationships were studied using phytoplanktonic pigments (chlorophylls and carotenoids) as organic natural markers. Pigments were separated by high-pressure liquid chromatography (HPLC). Comparison of pigment profiles from monospecific cultures of various taxonomic groups (Chlorophyceae, Bacillariophyceae and Cyanobacteria) and from Cladocera crustaceans (Daphnia magna) fed with these cultures, showed that the characteristic pigment associations of the different taxa are conserved during their transfer from primary producers to secondary consumers. Chromatographic profiles of the Bacillariophyceae and Chlorophyceae type were obtained fromDaphnia respectively fed with mixtures of a Chlorophyceae and a diatom species and mixture of a Chlorophyceae and a Cyanobacterium. This showed the importance of this method in demonstrating a possible selective feeding by the herbivorous zooplankton. The observation of pigment profiles of the Dinophyceae type following feeding of a zooplankton assemblage from Lake Pavin within this natural medium (phytoplankton dominated by a Dinophyceae) and of a Chlorophyceae type profile as the same assemblage was fed in the laboratory on phytoplankton from Lake Villerest (composed of about 80% Cyanobacteria and 20% Chlorophyceae), suggested that this method could be applied to the natural environment.
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    URL: http://dx.doi.org/10.1007/BF00877433
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  • 19
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    Non-radioactive detection of β-glucuronidase and chloramphenicol acetyltransferase activities in co-transformed protoplasts by HPLC (1993)
    Springer
    Plant cell reports 12 (1993), S. 361-365 
    Details
    ISSN: 1432-203X
    Keywords: CAT ; GUS ; HPLC ; Co-transformation ; Internal Standard ; Tobacco Protoplasts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The use of transient gene expression assays for the study of natural or engineered plant promoters is affected by a considerable degree of inter-experiment variability. As a means of obtaining interpretable data from a limited number of experiments, we worked out conditions for the simultaneous determi nation of the activity of two reporter genes, a “sample” and a “reference”, ona single extract of co-transformed protoplasts. ß-glucuronidase (GUS) and chloramphenicol acetyl transferase (CAT) genes, both under the control of the CaMV 35S promoter, were transferred into tobacco (Nicotiana tabacum L.) protoplasts on two independent plasmids. The parallel expression of the two reporter genes in several independent co-transformation experiments was verified. Conditions for the use of a single protoplast extraction buffer and for the simultaneous assay of both reporter gene activities were set up. A HPLC method for the non-radioactive determination of both enzyme activities on a single aliquot of the reaction mixture was developed. The resulting procedure was tested using the GUS gene as “reference” and the CAT gene, under the control of either wild type or upstream-deleted (−90) CaMV 35S promoter, as “sample”. The protocol is simple and allows the fast analysis of plant promoters in the presence of a true internal standard under conditions in which assay manipulations are reduced to a minimum and both reporter gene activities are subjected to the same experimental treatments.
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    URL: http://dx.doi.org/10.1007/BF00234693
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    Transformation of opium poppy (Papaver somniferum L.) with Agrobacterium rhizogenes MAFF 03-01724 (1992)
    Springer
    Plant cell reports 11 (1992), S. 132-136 
    Details
    ISSN: 1432-203X
    Keywords: Transformation ; Palaver somniferum ; Agrobacterium rhizogenes ; Morphinan alkaloids ; ELISA ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Transformed cultures of opium poppy (Papaver somniferum L.) were established by infecting hypocotyl segments with Agrobacterium rhizogenes MAFF 03-01724. Undifferentiated calli formed on the infected site grew satisfactorily on phytohormone-free solid medium in the dark and produced opine, mikimopine, which could not be detected in a normal culture. Numerous adventitious shoots developed from transformed calli during subculture. The transformed shoots separated individually were cultured on phytohormone-free MS solid medium at 22 ° C under 14 h/day light. They displayed wider leaves and longer internodes than shoots established from seeds or non-transformed root culture. The content of morphinan alkaloids in the cultures and regenerated shoots were quantitatively analyzed by enzyme-linked immunosorbent assay and high performance liquid chromatography. HPLC analysis revealed that non-transformed shoots contained much more codeine (1310 gmg/g dry wt.) than morphine (50 μg/g dry wt.), while the transformed shoot cultures did not contain morphine, although the level of morphinan alkaloids in the transformed shoots (213 μg morphine equivalents/g fr. wt.) was comparable to that in non-transformed shoots (182 μg morphine equivalents/g fr. wt.) by ELISA.
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    URL: http://dx.doi.org/10.1007/BF00232165
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    Characterization of cyclosporine a uptake in human erythrocytes (1994)
    Springer
    European journal of clinical pharmacology 46 (1994), S. 417-419 
    Details
    ISSN: 1432-1041
    Keywords: Cyclosporine A ; uptake ; human erythrocytes ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract More than 70% of cyclosporine A (CsA) is bound to erythrocytes at whole blood concentrations of 50–1000 ng·ml−1. Cytosolic CsA is bound to the erythrocyte peptidyl-prolyl cis-trans isomerase cyclophilin. Measurements of serum CsA levels under clinical conditions are hampered by a temperature-dependent translocation of CsA into erythrocytes during cooling of the probes to room temperature. In order to characterize the kinetics of CsA uptake and to find a specific uptake inhibitor, we developed a method to measure the velocity of uptake based on rapid cooling of the erythrocyte suspension. The total erythrocyte-binding capacity for CsA amounted to 43·10−5 nmol per 106 erythrocytes or 2.6·105 molecules per erythrocyte. Whereas the erythrocyte-binding capacity of CsA was temperature-independent between 10°C and 42°C, uptake kinetics of CsA were temperature-dependent. The Arrhenius plot for CsA uptake in human erythrocytes was linear and no transition temperature between 0°C and 42°C could be detected. Therefore the CsA uptake process in human erythrocytes did not fulfil the criteria of carrier-mediated transport. This indicates that CsA diffuses passively into human erythrocytes. Hence, erythrocyte CsA uptake cannot be specifically inhibited.
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    URL: http://dx.doi.org/10.1007/BF00191903
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    Differences in the bioavailability of dihydrotachysterol preparations (1994)
    Springer
    European journal of clinical pharmacology 47 (1994), S. 81-84 
    Details
    ISSN: 1432-1041
    Keywords: Dihydrotachysterol ; bioavailability ; pharmacokinetics ; human ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract The bioavailability of four preparations containing dihydrotachysterol (DHT2) was tested in two separate trials with administration of single, oral doses of 1 mg per individual. The relative bioavailability of corresponding preparations (capsules vs capsules and oral solution vs oral solution) was tested in a randomised, crossover pattern within the same group of volunteers. Two different groups of 24 healthy volunteers took part in each trial. Solution and capsule bioavailability was also compared inter-individually. A new sensitive HPLC-method (quantification limit 0.5 ng · ml-1) was used for the measurement of DHT2 concentration in serum. Three of the preparations tested had a similar bioavailability (mean AUC values of 195.5–223 ng · h · ml-1); the bioavailability of the fourth preparation (A.T.10 oral solution) was considerably lower (mean AUC value 111.5 ng · h · ml-1). The present dosage recommendations of all four preparations are identical. A new dosage recommendation is thus required for the oral solution with low bioavailability (A.T.10).
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    Using ofloxacin as a time marker in hair analysis for monitoring the dosage history of haloperidol (1994)
    Springer
    European journal of clinical pharmacology 47 (1994), S. 195-202 
    Details
    ISSN: 1432-1041
    Keywords: Ofloxacin ; Haloperidol ; Scalp hair ; time marker ; dosage history ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Hair samples were obtained 1–5 months after ingestion of the antimicrobial ofloxacin, which had been given for 1 or 3 days at the commencement of haloperidol administration, or when its dosage was reduced. The axial distribution of ofloxacin, haloperidol and its active metabolite, reduced haloperidol, was analysed in segments from single strands of hair. Ofloxacin was detected where the content of haloperidol and reduced haloperidol along the hair shaft showed a sharp change, corresponding to the change in dose. When we matched the time scale of the dosage history to the growth rate, which was estimated using ofloxacin as the time marker, the distribution of the haloperidol and reduced haloperidol precisely coincided with the rise and fall in the dose of haloperidol. These findings demonstrate that ofloxacin can serve as a time marker when drug distribution along the hair shaft is used to obtain the drug exposure history of an individual.
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    Pharmacokinetics of vinorelbine in man (1992)
    Springer
    European journal of clinical pharmacology 42 (1992), S. 545-547 
    Details
    ISSN: 1432-1041
    Keywords: Vinorelbine ; anti-neoplastic agents ; vinca alkaloids ; pharmacokinetics ; lung neoplasms ; HPLC ; assay method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of vinorelbine has been investigated by a new HPLC method in 8 cancer patients receiving 8 weekly doses (30 mg·m−2) administered by brief infusion (15 min). The plasma concentration-time curves showed a tri-exponential decay with a long terminal half-life (44.7 h) and a high volume of distribution (Vz=75.61·kg−1). The concentrations after the 8th infusion were significantly lower than after the 1st infusion, but without significant modification of CL (1.28 l·h−1·kg−1) or AUC (0.80 mg·l−1·h). The pharmacokinetic parameters exhibited wide inter-individual variations. The results are consistent with those of previous RIA studies, although the HPLC method appears to be more specific and more precise.
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    URL: http://dx.doi.org/10.1007/BF00314866
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    Circadian photoreception in the retinally degenerate mouse (rd/rd) (1991)
    Springer
    Journal of comparative physiology 169 (1991), S. 39-50 
    Details
    ISSN: 1432-1351
    Keywords: Photoreception ; Retinally degenerate ; Mouse ; Circadian ; Rods ; Cones ; 11-cis retinaldehyde ; Immunocytochemistry ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary We have examined the effects of light on circadian locomotor rhythms in retinally degenerate mice (C57BL/6J mice homozygous for the rd allele: rd/rd). The sensitivity of circadian photoreception in these mice was determined by varying the irradiance of a 15 min light pulse (515 nm) given at circadian time 16 and meauring the magnitude of the phase shift of the locomotor rhythm. Experiments were performed on animals 80 days of age. Despite the loss of visual photoreceptors in the rd/rd retina, animals showed circadian responses to light that were indistinguishable from mice with normal retinas (rd/+ and +/+). While no photoreceptor outersegments were identified in the retina of rd/rd animals (80–100 days of age), we did identify a small number of perikarya that were immunoreactive for cone opsins, and even fewer cells that contained rod opsin. Using HPLC, we demonstrated the presence and photoisomerization of the rhodopsin chromophore 11-cis retinaldehyde. The rd/rd retinas contained about 2% of 11-cis retinaldehyde found in +/+ retinas. We have yet to determine whether the opsin immunoreactive perikarya or some other unidentified cell type mediate circadian light detection in the rd/rd retina.
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    URL: http://dx.doi.org/10.1007/BF00198171
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    Search for polythionates in cultures of Chromatium vinosum after sulfide incubation (1990)
    Springer
    Archives of microbiology 153 (1990), S. 432-437 
    Details
    ISSN: 1432-072X
    Keywords: Chromatium vinosum ; Phototrophic bacteria ; Polysulfides ; Polythionates ; Elemental sulfur ; Sulfur globules ; Ion chromatography ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cultures of Chromatium vinosum, devoid of sulfur globules, were supplemented with sulfide and incubated under anoxic conditions in the light. The concentrations of sulfide, polysulfides, thiosulfate, polythionates and elemental sulfur (sulfur rings) were monitored for 3 days by ion-chromatography and reversed-phase HPLC. While sulfide disappeared rapidly, thiosulfate and elemental sulfur (S6, S7 S8 rings) were formed. After sulfide depletion, the concentration of thiosulfate decreased fairly rapidly, but elemental sulfur was oxidized very slowly to sulfate. Neither polysulfides (S x 2− ), polythionates (SnO 6 2− , n=4–6), nor other polysulfur compounds could be detected, which is in accordance with the fact that sulfide-grown cells were able to oxidize polysulfide without lag. The nature of the intracellular sulfur globules is discussed.
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    Rapid, quantitative HPLC analysis ofAsclepias fruticosa L. andDanaus plexippus L. cardenolides (1990)
    Springer
    Journal of chemical ecology 16 (1990), S. 3373-3382 
    Details
    ISSN: 1573-1561
    Keywords: Asclepias fruticosa ; milkweed ; Danaus plexippus ; monarch butterfly ; Lepidoptera ; Danaidae ; cardenolides ; HPLC ; gomphoside ; afroside ; digitoxin ; calactin ; calotropin ; cardenolide fingerprint ; cardiac glycosides ; internal standard
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The cardenolide extracts from latex and aerial parts ofAsclepias fruticosa and ofDanaus plexippus reared onA. fruticosa orA. curassavica were purified by adsorption chromatography on silica gel. HPLC analysis on a C18 reverse-phase column with an acetonitrile-water gradient as mobile phase, separated 28 compounds with a UV spectrum typical forcardenolides. Afroside and gomphoside (major components), as well as calotropagenin, calotoxin, calotropin, calactin, uscharidin, uscharin, and voruscharin, occurred as single peaks in the profiles of latex and aerial plant parts ofA. fruticosa. Calactin and calotropin were the major cardenolides inDanaus plexippus reared onA. fruticosa orA. curassavica. Quantitative data obtained with digitoxin as internal standard showed that 1.3–1.5% of the leaf cardenolides were sequestered byDanaus plexippus in which levels of 70–80μg cardenolide per butterfly were measured. The calotropin from the leaves was almost completely sequestered, and 10–13% of the calactin was stored by the butterfly, assuming that no conversion occurred in larval tissues.
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    Investigations on some aspects of chemical ecology of cogongrass,Imperata cylindrica (L.) Beauv. (1991)
    Springer
    Journal of chemical ecology 17 (1991), S. 343-352 
    Details
    ISSN: 1573-1561
    Keywords: Allelopathy ; cogongrass ; competition ; Imperata cylindrica ; HPLC ; interference ; weed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract To understand the interference mechanism of the weed, cogongrass,Imperata cylindrica (L.) Beauv., its effect on nutrient availability and mycoflora of its soil rhizosphere as well as nodule characteristics, root length, and root/shoot ratio of Melilotus parviflora Desf. were investigated. Additionally, the effect of the leachates of leaves and root/rhizome of cogongrass on seed germination and seedling characteristics of radish, mustard, fenugreek, and tomato were examined. Furthermore, to assess the qualitative and quantitative differences in phytochemical components, the leachates and the soils from three sampling sites (with cogongrass and 1.5 m and 3 m away from cogongrass) were analyzed with high-performance liquid chromatography (HPLC) on a C18 column. No significant difference in nutrient availability was found, but qualitative and quantitative differences in phenolic fractions were recorded in the three sampling sites. Furthermore, of the 19 fungi recorded in the soils, decreases in the number of colonies (per gram of soil) ofAspergillus fumigatus, A. niger, A. candidus, and an increase of A. flavus was recorded in the soils with cogongrass. The inhibition in nodule number, weight, nitrogen fixation (acetylene reduction activity), root length, and root/shoot ratio of Melilotus parviflora were noted. Percent seed germination, root and shoot length, fresh and dry weight of seedlings of different seeds were affected by the leachates of leaves and root/rhizome. It was found that root/rhizome leachate was more inhibitory than leaf leachate. However, the inhibition was higher in soil+leaves leachate than soil+root/rhizome leachate. HPLC analysis established that four compounds were contributed by the weed to the soil system even though their relative concentration varies in various leachates. It is surmised that these compounds cause allelopathic inhibition of growth characteristics of seeds tested. Significance of the data vis-a-vis the interference potential of the cogongrass is discussed.
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    Physiological sources of variation in chemical defense ofOreina gloriosa (Coleoptera: Chrysomelidae) (1993)
    Springer
    Journal of chemical ecology 19 (1993), S. 395-410 
    Details
    ISSN: 1573-1561
    Keywords: Oreina gloriosa ; Coleoptera ; Chrysomelidae ; chemical defense ; cardenolides ; quantitative variation ; aging ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The defensive secretion of the alpine chrysomelidOreina gloriosa is a complex mixture of mainly cardenolides and tyrosine betaine. Individually sampled secretions of adult laboratory-reared and field-collected beetles were analyzed by reverse-phase HPLC; 16 secretion components were quantified. Quantities and concentrations of different components were significantly affected by the age, sex, and reproductive status of individual beetles. Aging was correlated with marked increases (up to 4.4-fold) and decreases (up to 2.7-fold) of quantities and concentrations of several components. Differences between the sexes were smaller, but quantities of all components and concentrations of several components were larger in laboratory-reared females than in males. There was less of one component of the secretion in mated than unmated females, but the concentrations of four secretion components were higher (up to 1.6-fold) in mated females.
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    Incorporation of two18O atoms into a peptide during isoaspartyl repair reveals repeated passage through a succinimide intermediate (1994)
    Springer
    The protein journal 13 (1994), S. 553-560 
    Details
    ISSN: 1573-4943
    Keywords: Proteind-aspartyl/l-isoaspartyl carboxyl methyltransferase ; protein repair ; HPLC ; aging ; fast-atom bombardment mass spectrometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract To study the mechanism of protein carboxyl methyltransferase-driven repair of age-damaged sites in polypeptides, a modell-isoaspartyl peptide,l-isotetragastrin, was enzymatically repaired to normall-tetragastrin in the presence of18O-enriched water. By this design, the enrichment of18O atoms in the peptide would reflect the number of passages through a hydrolyzable succinimide intermediate during formation of the repaired product. Mass determinations by FAB mass spectrometry revealed repaired peptide with two18O atoms incorporated, demonstrating that more than a single cycle of methylation and demethylation is necessary to ensure stoichiometric repair.
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    Analysis of the carbohydrate composition of glycoproteins by high-performance liquid chromatography (1990)
    Springer
    The protein journal 9 (1990), S. 31-35 
    Details
    ISSN: 1573-4943
    Keywords: HPLC ; carbohydrates ; glycopeptides ; glycoprotuyns ; carjohydrate compositions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A procedure for rapid and sensitive analysis of carbohydrate in glycoproteins is described. After methanolysis and benzoylation of the monosaccharides and carbohydrates of a glycoprotein, the derivatized sugars were analyzed by reverse-phase high-performance chromatography using a Vydac C18 stationary phase and a mobile phase composed of a water/acetonitrile gradient. The advantages of this procedure over previously described methods are (1) the simple binary solvent system which is used requires no buffering salts and (2) separate sets of peaks from individual sugars obviate the usual need to reacetylate sugar amino groups.
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    Thiamine triphosphate activates an anion channel of large unit conductance in neuroblastoma cells (1993)
    Springer
    The journal of membrane biology 136 (1993), S. 281-288 
    Details
    ISSN: 1432-1424
    Keywords: Thiamine triphosphate ; Anion channel ; Oxythiamine ; Neuroblastoma ; Patch clamp ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract In neuroblastoma cells, the intracellular thiamine triphosphate (TTP) concentration was found to be about 0.5 μ m, which is several times above the amount of cultured neurons or glial cells. In inside-out patches, addition of TTP (1 or 10) μ m to the bath activated an anion channel of large unit conductance (350–400 pS) in symmetrical 150 mm NaCl solution. The activation occurred after a delay of about 4 min and was not reversed when TTP was washed out. A possible explanation is that the channel has been irreversibly phosphorylated by TTP. The channel open probability (P o) shows a bell-shaped behavior as a function of pipette potential (V p). P o is maximal for −25 mV〈V p〈10 mV and steeply decreases outside this potential range. From reversal potentials, permeability ratios of PCl/ PNa = 20 and PCl/Pgluconate = 3 were estimated. ATP (5 mm) at the cytoplasmic side of the channel decreased the mean single channel conductance by about 50%, but thiamine derivatives did not affect unit conductance; 4,4′ -diisothiocyanostilbene-2,2′-disulfonic acid (0.1 mm) increased the flickering of the channel between the open and closed state, finally leading to its closure. Addition of oxythiamine (1 mm), a thiamine antimetabolite, to the pipette filling solution potentiates the time-dependent inactivation of the channel at V p=−20 mV but had the opposite effect at +30 mV. This finding corresponds to a shift of P o towards more negative resting membrane potentials. These observations agree with our previous results showing a modulation of chloride permeability by thiamine derivatives in membrane vesicles from rat brain.
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    Expression of A/B zeins in single and double maize endosperm mutants (1992)
    Springer
    Theoretical and applied genetics 85 (1992), S. 407-414 
    Details
    ISSN: 1432-2242
    Keywords: Maize ; Zein ; Prolamins ; Mutants Genes ; HPLC ; Quantitation ; Epistasis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Zeins, the major endosperm proteins in maize (Zea mays L.), are deficient in the essential amino acids lysine and tryptophan. Some mutant genes, like opaque-2 (o2) and floury-2 (fl2), reduce the levels of A- and B-zeins, thereby improving maize's nutritional value. Other mutants, such as amylose-extender (ae), floury-1 (fl1), soft starch (h), dull-1 (du), shrunken-1 (sh1), sugary-1 (su1), sugary-2 (su2), and waxy (wx), primarily affect starch composition, but also alter zein composition. We undertook this study to examine the effects of some of these mutant genes on A/B-zein composition and to study the interactions of these genes in double-mutant combinations. Endosperm prolamins were extracted from inbred B37, ten near-isogenic single mutants (ae, du, fl1, fl2, h, o2, sh1, su1, su2, and wx), and most double-mutant combinations. Zeins in these extracts were fractionated by reversed-phase highperformance liquid chromatography (RP-HPLC) into 22–24 peaks. Of the resulting 22 major peaks the areas of 16 (per milligram endosperm) were significantly affected by individual mutant genes relative to the zein composition of the normal inbred. In combination these genes exhibited significant epistatic interactions in regulating the expression of individual A/B zeins. Epistatic interactions were judged to be significant when the amount of a peak in a double mutant differed from the averages for the peak in the two respective single mutants. The o2 gene, alone and in combination with other mutant genes, significantly decreased the amounts of many individual zeins. The effect of the o2 gene was the greatest of all the genes examined. Various clustering techniques were used to see if mutant effects could be grouped; among these was principal component analysis, a multivariate statistical technique that analyzes all peak sizes simultaneously. Three-dimensional scatter graphs were constructed based on the first three principal components. For the single mutants, these showed no relationships to gene actions; for the double mutants, however, this technique showed that four single mutants, o2, sh1, su1 and su2, had the greatest effects on zein composition when combined with each other and with the remaining six single mutants.
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    Rod-opsin immunoreaction in the pineal organ of the pigmented mouse does not indicate the presence of a functional photopigment (1993)
    Springer
    Cell & tissue research 274 (1993), S. 71-78 
    Details
    ISSN: 1432-0878
    Keywords: Pineal organ ; Retina ; Photoreceptors ; Photopigment ; Immunocytochemistry ; HPLC ; Autoradiography ; Mouse (C57BL)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The aim of the present study was to characterize the rod-opsin immunoreaction in the mammalian pineal organ. Pigmented mice (strain C57BL) were selected as the animal model. Immunocytochemical investigations involving the use of highly specific polyclonal and monoclonal antibodies against bovine rod-opsin (the apoprotein of the photopigment rhodopsin) showed that approximately 25% of all pinealocytes were rod-opsin immunoreactive. Immunoblotting techniques revealed three protein bands of approximately 40, 75, and 110 kDa; these were detected by the monoclonal antibody and the polyclonal antiserum in retinal and pineal extracts. These protein bands presumably represented the monomeric, dimeric and trimeric forms of rod-opsin. The amount of rod-opsin in retina and pineal organ was quantified by means of an enzyme-linked immunosorbent assay. This yielded 570±30 pmoles rod-opsin per eye and 0.3±0.05 pmoles rod-opsin per pineal organ. High pressure liquid chromatography analysis of whole eye extracts demonstrated the chromophoric group of the photopigment rhodopsin, 11-cis retinal, and its isomer, all-trans-retinal. A shift from 11-cis retinal to all-trans-retinal was found upon light adaptation. No retinals were detected in the pineal organ. Autoradiographic investigations showed that 3H-retinol, intraperitoneally injected into the animals, was incorporated into the outer and inner segments of retinal photoreceptors, but not into the pineal organ. It is concluded that the mouse pineal organ contains the authentic apoprotein of rhodopsin but that it lacks retinal derivatives as essential components of all known vertebrate photopigments. Consequently, the “photoreceptor-specific” proteins of the mammalian pineal organ are not involved in photoreception and phototransduction, but may serve other functions to be explored in future studies.
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    Localization of dopamine in the freshwater hydrozoanHydra attenuata (1992)
    Springer
    Cell & tissue research 270 (1992), S. 601-607 
    Details
    ISSN: 1432-0878
    Keywords: Dopamine ; HPLC ; Immunocytochemistry ; Hydra attenuata (Cnidaria)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary High performance liquid chromatography (HPLC), with electrochemical detection, is an analytical method sensitive enough to permit quantification of dopamine, dihydroxyphenylalanine (DOPA) and 5-S-cysteinyl DOPA in single or hemisected specimens ofHydra attenuata. Dopamine and 5-S-cysteinylDOPA appear to be the quantitatively predominant catechol compounds inH. attenuata, whereas DOPA is present in minor amounts. The presence of DOPA and 5-S-cysteinylDOPA, and the quantitative correlation between dopamine and these compounds in many specimens, suggests that dopamine inH. attenuata, as in higher animals, is formed through decarboxylation of DOPA. Contrary to the dopaminergic nerves in higher animals, DOPA inHydra seems to be oxidized and 5-S-cysteinyl DOPA is formed as a by-product. The oxidation of DOPA indicates that the hydroxylation of tyrosine into DOPA in the tissues ofH. attenuata is mediated by a tyrosinase rather than a tyrosine hydroxylase. Immunocytochemical methods demonstrate a highly variable distribution of dopamine in the tissues of different specimens ofH. attenuata. Dopamine immunoreactivity is confined to ectodermal tissue and can be found in several different cell types including nerve cells, battery cells, nematocytes, epithelial cells and interstitial undifferentiated cells. The large amounts of dopamine found in some specimens ofH. attenuata indicate some biological function, although its sporadic occurrence in neurites makes it less plausible as a generally utilized neurotransmitter in this animal.
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    Differences in the immunoreactivity to phenylethanolamine-N-methyltransferase in the central adrenergic neurons of four strains of rats (1991)
    Springer
    Cell & tissue research 265 (1991), S. 307-315 
    Details
    ISSN: 1432-0878
    Keywords: Brain, vertebrate ; Phenylethanolamine-N-methyltransferase ; Adrenaline ; Immunocytochemistry ; HPLC ; Rat (Wistar, Sprague-Dawley, Long Evans, Zucker)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Immunocytochemistry was used to compare the immunoreactivity of adrenergic neurons to a well characterized specific immunoserum to phenylethanolamine-N-methyltransferase (PNMT) in different strains of rats commonly used in research studies. In adult animals, marked differences were found in the PNMT-immunoreactivity of neurons between Wistar rats and other strains, resulting in a lower PNMT-immunostaining intensity (i) within neuronal perikarya of the medulla oblongata, and (ii) more strikingly, within nerve fibers and terminals located in various brain regions. This low PNMT-immunoreactivity of nerve fibers was detected both in 14- and 35-day-old Wistar rats. On the other hand, the HPLC measurement of catecholamines, in particular of adrenaline in the hypothalamus and the medulla oblongata, did not show any difference between adult Wistar and Sprague-Dawley rats. These data suggest that the low PNMT-immunoreactivity observed in central adrenergic neurons of the Wistar rats is related to the poor recognition of the antigen by the PNMT-antibody used. Possibly, these nerve cells mainly display an isoform of the enzyme that is immunologically different from the PNMT contained within the adrenergic neurons of other rat strains.
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    Cytophysiology of neurosecretory axon terminals in the brain of an annelid (Ophryotrocha puerilis, Polychaeta) (1991)
    Springer
    Cell & tissue research 264 (1991), S. 339-345 
    Details
    ISSN: 1432-0878
    Keywords: Neurosecretion ; Catecholamines ; HPLC ; Immunohistochemistry ; Glyoxylic acid fluorescence ; Ophryotrocha puerilis (Annelida)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the posterior part of the brain of the protandric polychaete Ophryotrocha puerilis neurosecretory cells form prominent axon terminals. The terminals are arranged in two complexes. The perikarya of these presumably monopolar neurons are scattered in the anterior part of the cerebral perikaryal layer. In females the terminals store large amounts of neurosecretory material. It has been suggested earlier that neurosecretions of the terminals may play a role during sex reversal from females to males. Application of histamine caused the release of neurosecretory material from the respective terminals in females. However, this discharge was not followed by sex reversal. Application of reserpine had no influence on the terminals. Neither by in vivo observation nor by ultrastructural analysis any effect of reserpine on the terminal complexes could be observed. In isolated terminals filled with neurosecretory material from females, catecholamines could not be detected by HPLC. Also, polyclonal antibodies against dopamine did not stain the terminal complexes. Furthermore, the complexes did not develop any fluorescence after glyoxylic acid treatment. Therefore, the present results contradict the hypothesis that the neurosecretory material of the respective axon terminals is catecholaminergic and that it is involved in sex differentiation. The function of the secretory neurons studied here remains unclear.
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    Loss of vitamin C (L-ascorbic acid) during long-term cold storage of Dutch table potatoes (1990)
    Springer
    Potato research 33 (1990), S. 125-130 
    Details
    ISSN: 1871-4528
    Keywords: dehydroascorbic acid ; HPLC ; Dutch Food Composition Table ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Loss of vitamin C (L-ascorbic acid) from Dutch table potatoes during storage at 5–6°C over 8 months from November to July, was studied in two seasons. L-Ascorbic and dehydroascorbic acid were analysed by HPLC. The amount of dehydroascorbic acid was negligible. Total loss of L-ascorbic acid varied between 21 and 60%. Some potato lots lost L-ascorbic acid rapidly in the first four months, others more gradually over the whole storage period. The L-ascorbic acid levels detected were 75–150% higher in the period March–June, but 35% lower in the period December–February than those indicated by the step-wise decreases in the Dutch Food Composition Table.
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    Purification of glyoxysomal polypeptides (1990)
    Springer
    Protoplasma 156 (1990), S. 130-138 
    Details
    ISSN: 1615-6102
    Keywords: Glyoxysomes ; Castor bean ; Enzyme purification ; Catalase ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A strategy for the rapid purification of proteins from glyoxysomes of castor bean (Ricinus communis cv. Hale) is described. The first step was to separate the proteins in the mixture on the basis of hydrophobicity by reversed phase high performance liquid chromatography using a gradient of increasing acetonitrile concentration. Individual protein peaks were collected and fractionated according to molecular mass by preparative polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The purified polypeptides were used to produce monospecific, polyclonal antibodies. One of these, an anti-catalase antibody, has been employed to assess the subcellular distribution of catalase in endosperm of maturing seeds, dry seeds and seedlings. During seed maturation 45% of the catalase activity was associated with structures sedimenting at high isopycnic densities (1.21 g/cm3). However, in dry seeds, only 6% or less of the catalase activity was associated with these dense particles. In 4-day seedlings 80% of catalase activity was associated with glyoxysomes (1.24 g/cm3). A novel catalase 59 kDa subunit was found in the cytosol of 4-day seedlings and in isolated organelles from maturing and dry seed.
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    Vitamin analysis of five planktonic microalgae and one macroalga (1991)
    Springer
    Journal of applied phycology 3 (1991), S. 259-264 
    Details
    ISSN: 1573-5176
    Keywords: vitamin analysis ; HPLC ; algae ; Tetraselmis suecica ; Isochrysis galbana ; Pavlova lutheri ; Skeletonema costatum ; Chaetoceros calcitrans ; Sargassum muticum ; cosmetology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Vitamin analysis was carried out on five microalgae used in aquaculture:Tetraselmis suecica, Isochrysis galbana, Pavlova lutheri, Skeletonema costatum andChaetoceros calcitrans and one macroalga,Sargassum muticum, which is invasive on the Atlantic shores of France. Both liposoluble (provitamin A, E, K) and hydrosoluble (B1, B2, B6, B12, C, PP) vitamins were quantified. For most of them, greater amounts were obtained in the algal products than in the usual sources. On a dry weight basis,Tetraselmis suecica contained 4280 μg g−1 provitamin A and 6323 μg g−1 vitamin E,Pavlova lutheri 1162 μg g−1 vitamin B12 and 837 μg g−1 vitamin C,Isochrysis galbana 2690 μg g−1 vitamin PP and 183 μg g−1 vitamin B6, andSkeletonema costatum 710 μg g−1 vitamin B1.
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    Extraction of chlorophyll and carotenoid pigments from Antarctic benthic mats for analysis by HPLC (1993)
    Springer
    Journal of applied phycology 5 (1993), S. 623-628 
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    ISSN: 1573-5176
    Keywords: -carotene ; chlorophylla ; cyanobacterial mats ; HPLC ; myxoxanthophyll
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The efficiency of 9:1 acetone-water, DMSO and boiling 9:1 ethanol-water in extracting chlorophyll and carotenoid pigments from benthic cyanobacterial mats from Antarctica for HPLC (high performance liquid chromatography) analysis was examined. Considerable breakdown of chlorophylla was observed after 5 min extraction in boiling ethanol and 2 h extraction in DMSO. Over 50% of the chlorophylla was degraded to chlorophyllidea and there was substantial loss of carotenoids after a 15 h exposure of ground cells to cold 9:1 acetone-water. Mild sonication of ground mat material in 9:1 acetone-water followed by a 4 h extraction at 4 ° C was found to minimise chlorophylla breakdown and dramatically improved the extraction efficiency of chlorophylla, myxoxanthophyll and -carotene.
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    In vivo and in vitro pharmacokinetics of 4,6-benzylidene-D-glucose (BG) in rats (1990)
    Springer
    Investigational new drugs 8 (1990), S. 149-157 
    Details
    ISSN: 1573-0646
    Keywords: benzylidene-glucosem ; BG ; HPLC ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In vivo pharmacokinetics of 4,6-benzylidene-D-glucose (BG) was investigated in rats following an i.v. bolus injection of 85 mg BG/kg body weight. High performance liquid chromatography (HPLC) was used to characterize and quantitate BG in whole blood or serum samples. It was found that BG rapidly disappeared with a half-life (t1/2)on the order of 10 min. At the same time a metabolite appeared which eluted before the double isomer peaks of BG. It increased in concentration from 0 to 30 min after initial i.v. injection of BG. Thereafter the metabolite was slowly removed or cleared from the animals. The t1/2 of the metabolite calculated from the time of maximum concentration was found to be about 1 h. BG was also metabolized by whole rat blood at 37°C, but on a different time scale in vitro. The t1/2 of BG in the in vitro assays was now about 4 h, as compared to 10 min in vivo. BG was not metabolized in rat plasma or rat serum. In contrast to in vivo data, the metabolite of BG was not reduced upon further incubation, but remained in blood samples with no reduction for at least 24 h. In addition, we found that protein synthesis was inhibited by approximately 50% when isolated rat hepatocytes were incubated with 3.2 mM BG. BG was slowly metabolized by hepatocytes to produce a metabolite indistinguishable (by HPLC) from that found in blood samples. Analysis of the metabolite by combined gas chromatography-mass spectrometric (GC-MS) methods identified it as being 1,3-benzylidene-D-glucitol. An intracellular reduction of BG by aldose reductase is proposed to occur.
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    A simple HPLC technique for accurate monitoring of mammalian cell metabolism (1994)
    Springer
    Cytotechnology 14 (1994), S. 123-128 
    Details
    ISSN: 1573-0778
    Keywords: HPLC ; mammalian cells ; metabolism ; pyrrolidone carboxylic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract We have developed a simple and accurate isocratic HPLC method, without any prederivatisation, for the determination of glucose, lactate, glutamine, glutamate, pyrrolidone carboxylic acid and alanine in samples from mammalian cell cultures. The method has been successfully validated with enzyme analysis for each of the compounds. Quantification of pyrrolidone carboxylic acid makes the correction for glutamine decrease due to chemical decomposition very simple and accurate, and avoids some possibly erroneous calculations.
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    Structures of asparagine-linked oligosaccharides from hen egg-yolk antibody (IgY). Occurrence of unusual glucosylated oligo-mannose type oligosaccharides in a mature glycoprotein (1991)
    Springer
    Glycoconjugate journal 8 (1991), S. 400-413 
    Details
    ISSN: 1573-4986
    Keywords: Asn-linked oligosaccharide ; hen egg-yolk ; IgY ; immunoglobulin ; p-aminobenzoic acid ethyl ester ; HPLC ; glucosylated oligosaccharide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Asparagine-linked oligosaccharides present on hen egg-yolk immunoglobulin, termed IgY, were liberated from the protein by hydrazinolysis. AfterN-acetylation, the oligosaccharides were labelled with a UV-absorbing compound,p-aminobenzoic acid ethyl ester (ABEE). The ABEE-derivatized oligosaccharides were fractionated by anion exchange, normal phase and reversed phase HPLC, and their structures were determined by a combination of sugar composition analysis, methylation analysis, negative ion FAB-MS, 500 MHz1H-NMR and sequential exoglycosidase digestions. IgY contained monoglucosylated oligomannose type oligosaccharides with structures of Glcα1-3Man7–9-GlcNAc-GlcNAc, oligomannose type oligosaccharides with the size range of Man5–9GlcNAc-GlcNAc, and biantennary complex type oligosaccharides with core region structure of Manα1-6(±GlcNAcβ1-4)(Manα1-3)Manβ1-4GlcNAcβ1-4(±Fucα1-6)GlcNAc. The glucosylated oligosaccharides, Glc1Man8GlcNAc2 and Glc1Man7GlcNAc2, have not previously been reported in mature glycoproteins from any source.
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    Quantitative determination of glutamate in a Rhodophyceae (Chondrus crispus) and four Phaeophyceae (Fucus vesiculosus, Fucus serratus, Cystoseira elegans, Cystoseira barbata) (1991)
    Springer
    Journal of applied phycology 3 (1991), S. 115-120 
    Details
    ISSN: 1573-5176
    Keywords: determination ; glutamate ; HPLC ; salt interference ; seaweed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A study was made to find a better method of analyzing the glutamate pool in seaweeds than the use of HPLC, which provides unsatisfactory results with material rich in alginates and salts. A method recommended elsewhere (Inglis A, Bartone N, Finlayson J, 1988, J. Biochem. Biophys. Methods 15: 249–254) for physiological fluids has been assayed and improved for algal samples. It consisted of the addition of lithium acetate before the phenylisothiocyanate derivatization, omission of one drying step and extraction of the derivative with heptane before chromatographic analysis. Neither salt nor alginates interfered with analysis.
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    Kinetic Analysis of Molecular Interconversion of Immunosuppressant FK506 by High-Performance Liquid Chromatography (1993)
    Springer
    Pharmaceutical research 10 (1993), S. 1785-1789 
    Details
    ISSN: 1573-904X
    Keywords: FK506 ; cyclosporins ; immunosuppressant ; conformational isomerization ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract High-performance liquid chromatography of FK506, a macrolide immunosuppressant, was performed on a reversed-phase column. The peak was broad with the column kept at room temperature, which was accounted for by slow interconversion between the two forms of FK506. With the use of a heated column, a sharp peak was observed because of the rapid interconversion at high temperature. When the column was cooled to 0°C, two sharp peaks were observed because essentially no interconversion occurred at 0°C during elution. Analysis of the chromatograms obtained at various eluant flow rates indicated that the conversion of the two forms follows first-order kinetics, and the apparent activation energies for the conversions were calculated. The interconvertibility between two molecular forms may be related to the immunosuppressive activity.
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    Selective Effect of Adjuvant Arthritis on the Disposition of Propranolol Enantiomers in Rats Detected Using a Stereospecific HPLC Assay (1993)
    Springer
    Pharmaceutical research 10 (1993), S. 294-299 
    Details
    ISSN: 1573-904X
    Keywords: propranolol ; inflammation ; stereoselective ; adjuvant arthritis ; enantiomer ; HPLC ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Nonstereospecific studies have indicated that the pharmacokinetics of propranolol (PR) are altered in inflammatory conditions such as arthritis. However, as the kinetics and dynamics of PR are stereoselective, we examined the effect of adjuvant arthritis (AA) on the disposition of the individual enantiomers. A novel normal-phase stereospecific HPLC assay for PR was developed involving chiral derivatization with S-(naphthyl)ethyl isocyanate and fluorescence detection. Oral and iv doses of racemic PR were administered to control and AA rats (n = 6). AA had no significant effect on either clearance or S:R ratio after iv doses. On the other hand, after oral doses, clearance was significantly decreased in AA. Although significant for both enantiomers, this effect was more pronounced on the less active R-enantiomer. The AUC R:S ratio was, therefore, significantly altered (AA, 14 ± 3.0; control, 4.3 ± 1.2). Increased total (S + R) plasma concentrations of PR in AA, possibly due to a reduced intrinsic clearance, therefore, reflect mainly increased concentrations of the less active R-enantiomer.
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    HPLC Assay for FK 506 and Two Metabolites in Isolated Rat Hepatocytes and Rat Liver Microsomes (1994)
    Springer
    Pharmaceutical research 11 (1994), S. 844-847 
    Details
    ISSN: 1573-904X
    Keywords: FK 506 ; in vitro metabolism ; rat hepatocytes ; rat liver microsomes ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Despite the current use of a standard two-step enzyme immunoassay in the clinical monitoring of the immunosuppressant FK 506, the lack of specificity for the parent drug in this assay renders it unsuitable for drug metabolism studies. An HPLC assay has been developed for studying the metabolism of FK 506 in isolated hepatocytes and microsomal mixtures. This assay allows simultaneous measurement of the parent drug and two of its time dependent metabolites. Metabolism of this drug was studied in intact rat liver cells and rat liver microsomes. We have shown that the metabolites observed are products of phase 1 oxidation reactions. Correlation of the 6β-testosterone hydroxylase activity with the FK 506 metabolite (Ml) initial formation rate is consistent with the belief that CYP 3A isozymes are involved in FK 506 metabolism in male rats.
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    Selective Precipitation of Interleukin-4 Using Hydrophobic Ion Pairing: A Method for Improved Analysis of Proteins Formulated with Large Excesses of Human Serum Albumin (1994)
    Springer
    Pharmaceutical research 11 (1994), S. 1492-1495 
    Details
    ISSN: 1573-904X
    Keywords: hydrophobic ion pairing ; interleukin-4 ; protein analysis ; HPLC ; human serum albumin ; formulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In order to ensure the stability of protein pharmaceuticals, human serum albumin (HSA) is often added as an excipient, frequently in large excess. This makes chromatographic analysis of the stability of the active protein difficult. In the case of interleukin-4 (IL-4), separation from HSA can be achieved to some degree by size exclusion chromatography, but some HSA co-elutes with the IL-4. Hydrophobic ion pairing provides a method for selective precipitation of IL-4 from HSA. Hydrophobic ion pairing involves the electrostatic interaction of ionic detergents with oppositely charged polypeptides. Even when HSA is present in fifty-fold excess (w/w), the resulting precipitate contains greater than 70% of the IL-4. Selective precipitation with SDS produces enhancements in IL-4 over HSA of more than 2000-fold. This approach permits subsequent facile analysis of IL-4 by conventional reverse phase HPLC.
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    Pharmacokinetics of individual components of teicoplanin in man (1990)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 18 (1990), S. 525-543 
    Details
    ISSN: 1573-8744
    Keywords: teicoplanin ; clinical pharmacokinetics ; individual components ; HPLC ; glycopeptide antibiotics ; kinetics-lipophilicity relationship
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Teicoplanin is a new antibiotic consisting of closely related glycopeptides. Following an iv bolus of 400 mg teicoplanin, the pharmacokinetics of the individual components A3-1, A2-1, A2-2, A2-3, A2-4, and A2-5 was studied in five healthy volunteers by HPLC. For each subject, plasma and urine data of the individual components were simultaneously fitted by a triexponential disposition model. No significant differences were observed between the components of the A2 group in the initial volume of distribution, 0.05–0.06 L/kg, and the half-life of the second disposition phase, 2.5–3.0 hr. Significant differences were found in the volume of distribution at steady state (Vss 0.42–0.92 L/kg), the half-lives of the first (0.18–0.26hr) and the third (48.1–66.8 hr) disposition phases, the total clearance (CL5.4–19.3 ml/hr per kg), the renal clearance (CLR 2.8–16.1 ml/hr per kg), and the percentage of the administered dose excreted in urine (Ae 53–85%). A highly significant correlation was found between the lipophilicity of the individual components increasing from A2-1 to A2-5, and the values of the kinetic parameters. As the lipophilicity increases the fraction unbound in plasma, Vss, CL, CLR, and Ae decrease, whereas the unbound steady state volume of distribution and the unbound nonrenal clearance increase. A modest degree of accumulation of each teicoplanin component in plasma is predicted to occur at steady state following repeated administration of teicoplanin given daily, with accumulation slightly higher for the more lipophilic components A2-4 and A2-5.
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    Enzymes involved in the metabolism of 3-hydroxy-3-methylglutaryl-coenzyme A in Catharanthus roseus (1994)
    Springer
    Plant cell, tissue and organ culture 38 (1994), S. 345-349 
    Details
    ISSN: 1573-5044
    Keywords: Catharanthus roseus ; enzyme ; HMG-CoA ; HPLC ; metabolism ; mevalonate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 3-Hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) is an important intermediate in various metabolic pathways, e.g. sterol biosynthesis, ketogenesis and leucine catabolism. The reactions and enzymes involved in the metabolism of HMG-CoA are briefly reviewed. These enzymes have been studied in Catharanthus roseus, a model system for studies on the regulation of secondary metabolic pathways, particularly those leading to terpenoidindole alkaloids. By using HPLC, three HMG-CoA catabolizing enzyme activities have been detected in protein extracts from suspension cultured C. roseus cells: HMG-CoA lyase, 3′-nucleotidase and (tentatively identified) 3-methylglutaconyl-CoA hydratase (HMG-CoA hydrolyase). The enzymes have been partially purified. HMG-CoA is formed from three molecules of acetyl-CoA, via reactions which are catalyzed by two (as in yeast and animal cells, via intermediacy of acetoacetyl-CoA) or by just one enzyme (as in e.g. radish). It is yet not clear which process occurs in C. roseus.
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    Leaf Xanthophyll content and composition in sun and shade determined by HPLC (1990)
    Springer
    Photosynthesis research 23 (1990), S. 331-343 
    Details
    ISSN: 1573-5079
    Keywords: HPLC ; shade plants ; sun plants ; violaxanthin ; xanthophyll cycle ; zeaxanthin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract As a part of our investigations to test the hypothesis that zeaxanthin formed by reversible de-epoxidation of violaxanthin serves to dissipate any excessive and potentially harmful excitation energy we determined the influence of light climate on the size of the xanthophyll cycle pool (violaxanthin + antheraxanthin + zeaxanthin) in leaves of a number of species of higher plants. The maximum amount of zeaxanthin that can be formed by de-epoxidation of violaxanthin and antheraxanthin is determined by the pool size of the xanthophyll cycle. To quantitate the individual leaf carotenoids a rapid, sensitive and accurate HPLC method was developed using a non-endcapped Zorbax ODS column, giving baseline separation of lutein and zeaxanthin as well as of other carotenoids and Chl a and b. The size of the xanthophyll cycle pool, both on a basis of light-intercepting leaf area and of light-harvesting chlorophyll, was ca. four times greater in sun-grown leaves of a group of ten sun tolerant species than in shade-grown leaves in a group of nine shade tolerant species. In contrast there were no marked or consistent differences between the two groups in the content of the other major leaf xanthophylls, lutein and neoxanthin. Also, in each of four species examined the xanthophyll pool size increased with an increase in the amount of light available during leaf development whereas there was little change in the content of the other xanthophylls. However, the α-carotene/β-carotene ratio decreased and little or no α-carotene was detected in sun-grown leaves. Among shade-grown leaves the α-carotene/β-carotene ratio was considerably higher in species deemed to be umbrophilic than in species deemed to be heliophilic. The percentage of the xanthophyll cycle pool present as violaxanthin (di-epoxy-zeaxanthin) at solar noon was 96–100% for shade-grown plants and 4–53% for sun-grown plants with zeaxanthin accounting for most of the balance. The percentage of zeaxanthin in leaves exposed to midday solar radiation was higher in those with low than in those with high photosynthetic capacity. The results are consistent with the hypothesis that the xanthophyll cycle is involved in the regulation of energy dissipation in the pigment bed, thereby preventing a buildup of excessive excitation energy at the reaction centers.
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    Composition of photosynthetic pigments in thylakoid membrane vesicles from spinach (1993)
    Springer
    Photosynthesis research 35 (1993), S. 171-178 
    Details
    ISSN: 1573-5079
    Keywords: carotenoids ; chlorophylls ; HPLC ; phase partition ; xanthophylls
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Thylakoid membranes from spinach were fragmented mechanically and separated into vesicles originating from grana and stroma-exposed lamellae (Andreasson et al. (1988) Biochim Biophys Acta 936: 339–350). The grana vesicles were further fragmented and separated into smaller vesicles originating from different parts of the grana (Svensson and Albertsson (1989) Photosynth Res 20: 249–259). All vesicles so obtained were analyzed with respect to chlorophyll and carotenoid composition by reverse phase HPLC. For all fractions the following relations (mole/mole) were found: 1 carotenoid per 4 chlorophyll (a+b), 2 lutein per 5 chlorophyll b and 5 violaxanthin per 100 chlorophyll (a + b). The contents of lutein and neoxanthin were each linearly related to chlorophyll b and β-carotene was linearly related to chlorophyll a.
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    The identification and metabolism of GA9 and its metabolites in seed coats and shoots of pea, line G2 (1991)
    Springer
    Plant growth regulation 10 (1991), S. 13-26 
    Details
    ISSN: 1573-5087
    Keywords: Gibberellins ; GA9 ; GA20 ; GA29 ; GA51 ; GA70 ; GA29-catabolite ; GA51-catabolite ; Pisum sativum ; shoot ; seed coats ; testa ; HPLC ; GC-MS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract [3H]gibberellin A9 was applied to shoots or seed parts of G2 pea to produce radiolabeled metabolites. These were used as markers during purification for the recovery of endogenous GA9 and its naturally occurring metabolites. GA9 and its metabolites were purified by HPLC, derivatized and examined by GC-MS. Endogenous GA9, GA20, GA29 and GA51 were identified in pea shoots and seed coats. GA51-catabolite and GA29-catabolite were also detected in seed coats. GA70 was detected in seed coats following the application of 1 μg of GA9. Applied [3H]GA9 was metabolized through both the 13-hydroxylation and 2β-hydroxylation pathways. Labeled metabolites were tentatively identified on the basis of co-chromatography on HPLC with endogenous compounds identified by GC-MS. In shoots [3H]GA51 and [3H]GA51-catabolite were the predominant metabolites after 6 hrs, but by 24 hrs there was little of these metabolites remaining, while [3H]GA29-catabolite and an unidentified metabolite predominated. In seed coats [3H]GA51 was the initial product, later followed by [3H]GA51-catabolite and an unidentified metabolite (different from that in shoots), with lesser amounts of [3H]GA20, [3H]GA29 and [3H]GA29-catabolite. [3H]GA70 was a very minor product in both cases. [3H]GA9 was not metabolized by pea cotyledons.
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    Evidence for the biological turnover of thiols in anoxic marine sediments (1991)
    Springer
    Biogeochemistry 13 (1991), S. 117-135 
    Details
    ISSN: 1573-515X
    Keywords: mercaptans ; methanethiol ; Inhibitors ; BES ; 3-MPA ; adsorption ; HPLC ; nucleophiles ; sulfate-reducing bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The concentrations of methanethiol (MSH) and 3-mercaptopropionate (3-MPA) increased for a period of up to 24 h in fresh slurries of anoxic Biscayne Bay sediments. Other endogenous thiols such as glutathione (GSH) deceased immediately after slurry preparation or were not detectable at all. The maximum concentrations reached by 3-MPA and MSH were sometimes as high as 1 μM, but were usually in the 100 to 300 nM range. After the initial increases, the concentrations of these thiols decreased rapidly to nearly constant levels of ∼20 nM for MSH and 〈 1nM for 3-MPA. In pre-incubated slurries, which had constant levels of thiols, the addition of microbial inhibitors including tungstate, molybdate, chloroform, and a mixture of chloramphenicol plus tetracycline caused MSH and 3-MPA to accumulate steadily. In the presence of inhibitors, accumulation rates of MSH ranged from 18 to 730 nM · d-1 and those of 3-MPA ranged from 0 to 185 nM · d-1. Tungstate and chloroform generally gave the highest accumulation rates, while molybdate gave the lowest, possibly due to its complexation with sulfhydryl compounds. BES (2-Bromoethanesulfonate) was also tested for its effects, but no 3-MPA and only trace amounts (19 nM · d-1) of MSH accumulated with this treatment. However, additions of BES (10 mM) to sulfidic sediments caused significant (∼8 μM · d-1) production of 2-mercaptoethanesulfonate (HS-CoM). Formation of HS-CoM was abiotic and was due to sulfide attack on the bromine atom in BES. The accumulations of 3-MPA and MSH in the presence of several different microbial inhibitors, suggests that these thiols may turn over in anoxic sediments. The relatively low concentrations of thiols observed in pore water profiles may be due to continuous microbial removal of these compounds. Much larger amounts of thiols were associated with sediment particles than present in the pore water. Evidence is presented which suggests that bound thiols may be exchangeable with the porewater, and therefore potentially available for microbial consumption.
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    Chromatographic and immunological identification of gonadotropin-releasing hormone in five marine teleosts (1993)
    Springer
    Fish physiology and biochemistry 12 (1993), S. 337-345 
    Details
    ISSN: 1573-5168
    Keywords: GnRH ; salmon GnRH ; chicken GnRH-II ; HPLC ; RIA ; bluefin tuna ; red seabream ; black seabream ; red spotted grouper ; Japanese flounder
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Brain extracts from bluefin tuna, Thunnus thynnus, red seabream, Pagrus major, black seabream, Acanthopagrus schlegeli, red spotted grouper, Epinephelus akaara and Japanese flounder, Paralichthys olivaceus, were analyzed by high performance liquid chromatography (HPLC) and specific radioimmunoassays. Immunoreactive material co-eluting from HPLC with salmon gonadotropin-releasing hormone (GnRH) and chicken GnRH-II, respectively, was found in all five species. In addition, a GnRH immunoreactive fraction showing the same HPLC retention time as lamprey GnRH-I was detected in the brain extracts of all species examined when using an unspecific radioimmunoassay which detects several GnRH forms, including lamprey GnRH-I. In the Japanese flounder brain extract, a fourth GnRH immunoreactive fraction was detected with the unspecific radioimmunoassay which did not co-elute with any of the six synthetic GnRH standards used in the present study.
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    The role of Mg2+ in the hydrolytic activity of the isolated chloroplast ATPase: Study by high-performance liquid chromatography (1994)
    Springer
    Journal of bioenergetics and biomembranes 26 (1994), S. 335-346 
    Details
    ISSN: 1573-6881
    Keywords: Chloroplast ATPase ; reaction rate ; HPLC ; Mg2+
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Physics
    Notes: Abstract The influences of total magnesium ion concentration at different total ATP concentrations, and of total ATP concentration, for different total magnesium ion concentrations, on the enzymatic rate of the isolated chloroplast F1 ATPase, have been followed by a chromatographic method consisting in the separation and determination of ADP. From the various series of curves, it is concluded that the experimental results (position of the maxima,K m values) are better fitted by a mechanism involving the activation of the enzyme by magnesium ion and hydrolysis of free ATP, rather than by the classical mechanism, for which the enzyme hydrolyzes the MgATP complex and is inhibited by Mg2+. Although the equations giving the reaction rate are similar in the two cases, the calculated values ofK m are widely different. The value obtained from the classical mechanism does not agree withK D , the dissociation constant of the enzyme-substrate complex, measured by the Hummel and Dreyer method. Moreover, when the total ATP concentration tends toward the total magnesium ion concentration, the nucleotide binding to the enzyme tends toward zero, although it should be maximum if MgATP were the true substrate. Finally, the inhibitory effect of Na+ is more easily explained as a competition between this ion and the activating Mg2+, than by the classical mechanism.
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    A new strain ofRhodotorula rubra isolated from yogurt (1992)
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    Journal of industrial microbiology and biotechnology 11 (1992), S. 43-51 
    Details
    ISSN: 1476-5535
    Keywords: Rhodotorula rubra sp. TP1 ; Pigment characterization ; HPLC ; TLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary A new strain ofRhodotorula rubra has been isolated from yogurt which shows promise as a source for pigment and protein feed for aquacultured animals. The pigment was extracted by rupturing the cells with the French press followed by extraction with acetone and purification of the acetone extract using petroleum ether and cold 10% NaCl. The absorption spectrum indicated that the pigment was a carotenoid, the chemistry of which was examined using nuclear magnetic resonance, mass spectroscopy and resonance Raman spectroscopy. A reverse-phase HPLC equipped with octadecylsilylated (ODS) silica column showed nearly 80-times more pigment production under similar cultural conditions thatPhaffia rhodozyma. The isolate grows optimally at 20°C when grown on a variety of media. Its morphology has been studied using transmission electron microscopy, scanning electron microscopy and phase contrast microscopy. From the results of the API system, the isolate was identified asRhodotorula rubra.
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    Ontogenic variation of biologically active metabolites ofPteridium aquilinum (L. Kuhn) pterosins A and B, and ptaquiloside in a bracken population of the tropical andes (1992)
    Springer
    Journal of chemical ecology 18 (1992), S. 1405-1420 
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    ISSN: 1573-1561
    Keywords: Bracken fern ; Pteridium aquilinum var.Caudatum ; tropics ; ptaquiloside ; pterosin A ; pterosin B ; quantitation ; HPLC ; blade growth ; semiochemicals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A negative correlation has been found between the amounts of pterosins A and B and ptaquiloside per biomass unit, and the growth stage of the blade of bracken. Their concentration decreased progressively from the crozierto the mature frond, where it attained less than 5% of the initial value. The growth was measured following the total blade length, its height, moisture content, and time of emergence from the soil surface. Quantitation of these compounds was achieved by HPLC using a water extraction, methylene chloride treatment, and silica gel microcolumn cleanup sequence. Pterosins were unevenly distributed in the blade, whereas ptaquiloside maintained a constant concentration throughout. Rhizomes contained only minor amounts of these compounds. Their possible role as semiochemicals in bracken is discussed.
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    Biologically active secondary metabolites of barley. II. Phytotoxicity of barley allelochemicals (1993)
    Springer
    Journal of chemical ecology 19 (1993), S. 2231-2244 
    Details
    ISSN: 1573-1561
    Keywords: Allelopathy ; allelochemicals ; phytotoxin ; gramine ; hordenine ; HPLC ; TEM ; micrograph ; autophagy ; barley ; Hordeum vulgare ; Sinapis alba
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The release of alkaloids by barley was quantified by HPLC. Hordenine was released from the roots of barley in a hydroponic system for up to 60 days. The amount reached a maximum, 2μg/plant/day, at 36 days, then declined. Effects on white mustard by hordenine and gramine included reduction of radicle length and apparent reduction in health and vigor of radicle tips. Transmission electron microscopic examination of white mustard radicle tips exposed to hordenine and gramine showed damage to cell walls, increase in both size and number of vacuoles, autophagy, and disorganization of organelles. The evidence of the morphological and primary effects of barley allelochemicals at the levels released by living plants indicates that the biologically active secondary metabolites of barley may lead to a significant role in selfdefense by the crop.
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    A growth inhibitory factor from lambsquarters (Chenopodium album) (1994)
    Springer
    Journal of chemical ecology 20 (1994), S. 957-967 
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    ISSN: 1573-1561
    Keywords: Chenopodium album ; lambsquarters ; decomposition ; inhibition ; HPLC ; paper chromatography ; phenolics ; radish ; solvent extraction ; ultrafiltration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Aqueous extract of air-dried lambsquarters (Chenopodium album) at 25 mg/ml significantly inhibited germination and growth of radish and wheat seeds. Soybean seed germination was not inhibited; however, hypocotyl growth was significantly reduced. Germination of radish seeds in sand amended with pulverized lambsquarters shoots at 2 and 4 mg/g was reduced 40 and 95%, respectively. Shoot dry weight and plant height were also reduced 30 and 9%, respectively, at 4 mg/g, but not at 2 mg/g concentration. Residues after extraction with water incorporated in sand were not inhibitory, indicating water solubility of the inhibitor(s). Aqueous extract of shoots decomposed for five days lost nearly 40% of its inhibitory effect; 20% of it still persisted in the extract of shoots decomposed for 30 days. The filtrate from ultrafiltration of aqueous extract through a pad of molecular-weight cutoff 1000 inhibited radish seeds germination and growth, indicating that the molecular weight of the inhibitor(s) was less than 1000. Partitioning of the aqueous extract by a series of solvents resulted in isolation of an inhibitor(s) in the butanol fraction. Seven phenolics were identified in this fraction using high-performance liquid chromatography (HPLC). Paper chromatographic analysis of the butanol fraction revealed six bands, of which one band withR f =0.83 inhibited germination and growth of radish seeds. Chlorogenic acid identified by HPLC appeared to be the principal component of the phytotoxin.
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    Analysis, isolation and insecticidal activity of linear furanocoumarins and other coumarin derivatives fromPeucedanum (Apiaceae: Apioideae) (1994)
    Springer
    Journal of chemical ecology 20 (1994), S. 2035-2054 
    Details
    ISSN: 1573-1561
    Keywords: Apiaceae ; Peucedanum ; Lepidoptera ; Noctuidae ; Spodoptera littoralis ; HPLC ; preparative isolation ; furocoumarins ; furanocoumarins ; pyranocoumarins ; growth inhibition ; dietary utilization ; plant chemical diversity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Peucedanum arenarium Waldst. & Kit.,P. austriacum (Jacq.) Koch,P. coriaceum Reichenb.,P. longifolium Waldst. & Kit,P. officinale L.,P. oreoselinum (L.) Moench,P. ostruthium L., andP. palustre (L.) Moench accumulate different structural types of coumarins including simple coumarins, linear furanocoumarins, linear dihydropyranocoumarins, angular dihydrofuranocoumarins and angular dihydropyranocoumarins. Linear furanocoumarins, known for various biological activities, include some well-known antifeedants, such as bergapten, isopimpinellin, and xanthotoxin. The aim of this investigation was to screen the diverse coumarins fromPeucedanum for insecticidal activity. LC was used to analyze and isolate coumarins for the bioassays. A growth inhibition bioassay with 17 derivatives, comprising all structural types fromPeucedanum, carried out withSpodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) as test organism, indicated the majority of the linear furanocoumarins and the angular dihydrofuranocoumarin athamantin as active compounds. Oxygenation of the prenyl residue of linear furanocoumarins decreased activity. Further formation of an ester with angelic acid even resulted in complete inactivity. Five active linear furanocoumarins, bergapten, isopimpinellin, xanthotoxin, isoimperatorin, and imperatorin, and two linear furanocoumarins with a substituted furan ring, peucedanin and 8-methoxypeucedanin, were compared in a dietary utilization bioassay. Relative growth rate (RGR) and relative consumption rate (RCR) divided the tested coumarins in three groups of similar activity. Isopimpinellin and peucedanin slightly decreased RGR and RCR of the treated larvae, and xanthotoxin, isoimperatorin, and 8-methoxypeucedanin heavily decreased RGR and RCR. Bergapten and imperatorin differed by the lowest RGR values and rather high RCR values. The effects caused by these two coumarins indicate specific postingestive toxicity. The results obtained in this study add to the reputation of coumarins to be an effective chemical defense, postulating that chemical diversity is a necessary trait for well-defended plants.
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    Biologically active secondary metabolites of barley. III. A method for identification and quantification of hordenine and gramine in barley by high-performance liquid chromatography (1993)
    Springer
    Journal of chemical ecology 19 (1993), S. 2245-2254 
    Details
    ISSN: 1573-1561
    Keywords: Barley ; Hordeum vulgare ; allelochemicals ; hordenine ; gramine ; quantification ; HPLC ; cultivars
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A method was devised for the extraction and quantification of hordenine and gramine from barley (Hordeum vulgare) tissue using HPLC techniques. Quantification was by peak area, the relationship between peak area and concentration of authentic standards being linear for both hordenine and gramine. Significant differences in the ability of three lines of barley to produce hordenine and gramine were detected using this method.
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    Evidence for the presence of plant growth regulators in commercial seaweed products (1993)
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    Plant growth regulation 13 (1993), S. 21-29 
    Details
    ISSN: 1573-5087
    Keywords: HPLC ; seaweed concentrate ; plant hormones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Although seaweeds and various seaweed products have been utilized in agricultural practices for many years, the precise mechanism by which they elicit their beneficial growth responses is still not fully understood. The amount of mineral nutrients in commercial preparations cannot account for the magnitude of the responses. Some other factor, such as the presence of endogenous plant growth regulators is, therefore, thought to be involved. This paper reviews the literature supporting evidence for the occurrence of plant hormones in commercial seaweed preparations.
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    Identification of the cytokinins in red pine seedlings (1993)
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    Plant growth regulation 13 (1993), S. 169-178 
    Details
    ISSN: 1573-5087
    Keywords: bioassay ; cytokinins ; episodic growth ; HPLC ; mass spectra ; Pinus resinosa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Zeatin-9-riboside was identified in shoots and roots of Pinus resinosa by GC-MS analysis of its permethyl derivative. Based on their chromatographic properties on Sephadex LH-20 and C18 HPLC, and their susceptibility to enzymatic degradation, several other cytokinins have been tentatively identified. The basic fraction of both the roots and shoots contained zeatin, whereas the shoots contained dihydrozeatin-O-glucoside and the roots contained zeatin-O-glucoside. Zeatin-9-riboside monophosphate, isopentenyladenosine monophosphate ([9R-5′P]iP) and glucosyl phosphate derivatives were detected in the acidic fractions from both roots and shoots. There were equivalent amounts of [9R-5′P]iP in both roots and shoots. The presence of equivalent amounts of [9R-5′P]iP in both the roots and shots suggests that cytokinin biosynthesis may be occurring in both locations.
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    Identification of the metabolites of Indole-3-acetic acid in growing hypocotyls of Lupinus albus (1990)
    Springer
    Plant growth regulation 9 (1990), S. 315-327 
    Details
    ISSN: 1573-5087
    Keywords: IAA conjugation ; IAA decarboxylation ; HPLC ; Lupinus albus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The products of indole-3-acetic acid (IAA) metabolism by incubating hypocotyl sections and decapitated seedlings of Lupinus albus were investigated. Single treatments using [1-14C]-IAA, [2-14C]-IAA or [5-3H]-IAA and double treatments using [1-14C]-IAA+[5-3H]-IAA were carried out. Extracts from treated plant material were analyzed by paper chromatography (PC), Thin layer chromatography (TLC), and high performance liquid chromatography (HPLC). When hypocotyl sections were incubated in [2-14C]-IAA, several IAA decarboxylation products including indole-3-aldehyde (IA1), indole-3-methanol (IM), 3-hydroxymethyloxindole (HMOx), methyleneoxindole (MOx) and 3,3′-bisindolylmethane (BIM) were detected in the 95% ethanol extract; a latter extraction with 1M NaOH rendered IAA, IM and BIM, suggesting that conjugated auxins were formed in addition to conjugated IM. In sections incubated with [1-14C]-IAA, the 1M NaOH extraction also produced IAA so confirming the formation of conjugated auxins. The same decarboxylation products and two conjugated auxins, indole-3-acetylaspartic acid (IAAsp) and 1-O-(indole-3-acetyl)-β-D-glucose (IAGlu), were detected in the acetonitrile extracts from decapitated seedlings treated with [5-3H]-IAA. After a double isotope treatment ([1-14C]-IAA+[5-3H]-IAA) of decapitated seedlings, the ratio 14C/3H measured in the HPLC fractions of the acetonitrile extracts confirmed the presence of decarboxylation products as well as conjugated auxins.
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    Amino acids as a nitrogen source for Chlorella symbiotic with green hydra (1991)
    Springer
    Hydrobiologia 216-217 (1991), S. 369-376 
    Details
    ISSN: 1573-5117
    Keywords: green hydra ; Chlorella ; symbiosis ; amino acids ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Supply of amino acids may be important in controlling cell division of Chlorella symbiotic with green hydra. Freshly isolated symbionts display characteristics of N-limited algae, and low pH in perialgal vacuoles and high levels of host glutamine synthetase (GS) limit uptake of ammonium. Movement of tritiated amino acids from host to algal pools suggests that symbiotic algae utilize amino acids derived from host digestion of prey. Amounts are significant in relation to host and algal amino acids pools. During host starvation, glutamine produced by host GS may be important as a nitrogen supply to the algae, which take up this amino acid at high rates at low pH.
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    Variations in biochemical parameters of Heterocapsa sp. and Olisthodiscus luteus grown in 12:12 light:dark cycles II. Changes in pigment composition (1992)
    Springer
    Hydrobiologia 238 (1992), S. 149-157 
    Details
    ISSN: 1573-5117
    Keywords: Heterocapsa sp. ; Olisthodiscus luteus ; cycles ; pigments ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthetic pigment composition was studied in batch cultures of Heterocapsa sp. and Olisthodiscus luteus growing exponentially in a 12:12 light:dark cycle. Both species divided in the dark. The synthesis of pigments was continuous for both species. However for chlorophyll c and peridinin, in Heterocapsa sp., and chlorophyll c and fucoxanthin, in O. luteus, (pigments belonging to light harvesting complexes) the synthesis was significantly higher during the light period. Concentrations per total cell volume (TCV) of chlorophyll a, chlorophyll c, peridinin and diadinoxanthin in Heterocapsa sp., and chlorophyll a, chlorophyll c, fucoxanthin and violaxanthin in O. luteus, showed a maximum at the onset of light and decreased during the light period. The values of the chlorophyll a:chlorophyll c, chlorophyll a:peridinin and chlorophyll a:fucoxanthin ratios are compared with data reported in the literature.
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    Subunit organization of PSI particles from brown algae and diatoms: polypeptide and pigment analysis (1990)
    Springer
    Photosynthesis research 23 (1990), S. 181-193 
    Details
    ISSN: 1573-5079
    Keywords: brown algae ; diatoms ; dodecylmaltoside ; HPLC ; pigment protein complexes ; photosystem I
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract P700 enriched fractions were isolated from two brown algae and one diatom using sucrose density centrifugation after digitinin solubilization. They had a Chl a/P700 ratio of about 250 to 375 according to the species, they were enriched in long-wavelength absorbing Chl a and exhibited a fluorescence emission maximum at 77 K near 720 nm. They all presented a major polypeptide component at 66±2 kDa, but their polypeptide composition was rather complex and somewhat different from one species to another. Further solubilization with dodecylmaltoside of those ‘native’ PSI particles allowed the separation of two or three fractions. The lightest, xanthophyll-rich, fraction was identified to be a light-harvesting complex. It contained no P700 and had a major polypeptide of molecular weight near 20 kDa (at the same molecular weight than the respective LH ‘native’ fraction of each species) and exhibited a 77 K peak fluorescence emission at 685 nm. The other fractions were enriched in P700 and almost entirely depleted in xanthophylls. When two of them are present, they both exhibited a major polypeptide at 66±2 kDa and were totally devoid of the LH polypeptide, but the two fractions widely differed one from another in the abundance and molecular weight of the other polypeptide components. The most purified of these two fractions presented a composition similar to PSI core complex from green plants.
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    URL: http://dx.doi.org/10.1007/BF00035009
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    Separation of bacteriochlorophyll homologues from green photosynthetic sulfur bacteria by reversed-phase HPLC (1994)
    Springer
    Photosynthesis research 41 (1994), S. 157-164 
    Details
    ISSN: 1573-5079
    Keywords: bacterial pigments ; bacteriochlorophyll homologues ; chlorobiaceae ; HPLC ; pigment analyses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A reversed-phase High Performance Liquid Cromatography (HPLC) method has been developed to accurately separate bacteriochlorophyllsc, d ande homologues in a reasonably short run time of 60 minutes. By using this method, two well-defined groups of bacteriochlorophyll homologue peaks can be discriminated. The first one consists of 4 peaks (min 24 to 30), which corresponds to the four main farnesyl homologues. The second peak subset is formed by a cluster of up to 10 minor peaks (min 33 to 40). These peaks can be related with series of several alcohol esters of the different chlorosome chlorophylls. The number of homologues was, however, quite variable depending on both, the bacteriochlorophyll and the bacterial species. The method hereby described, also provides a good separation of other photosynthetic pigments, either bacterial (Bacteriochlorophylla, chlorobactene, isorenieratene and okenone) or algal ones (Chlorophylla, Pheophytina and β-carotene). A preliminary screening of the homologue composition of several green photosynthetic bacterial species and isolates, has revealed different relative quantitative patterns. These differences seem to be related to physiological aspects rather than to taxonomic ones. The application of the method to the study of natural populations avoids the typical drawbacks on the pigment identification of overlapping eukaryotic and prokaryotic phototrophic microorganisms, giving further information about their physiological status.
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    Evidence for the existence of trimeric and monomeric Photosystem I complexes in thylakoid membranes from cyanobacteria (1994)
    Springer
    Photosynthesis research 40 (1994), S. 279-286 
    Details
    ISSN: 1573-5079
    Keywords: cyanobacteria ; HPLC ; monomer ; Photosystem I ; state transitions ; trimer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In cyanobacteria, solubilization of thylakoid membranes by detergents yields both monomeric and trimeric Photosystem I (PS I) complexes in variable amounts. We present evidence for the existence of both monomeric and trimeric PS I in cyanobacterial thylakoid membranes with the oligomeric state depending ‘in vitro’ on the ion concentration. At low salt concentrations (i.e.≤10 mM MgSO4) PS I is mainly extracted as a trimer from these membranes and at high salt concentrations (i.e.≥150 mM MgSO4) nearly exclusively as a monomer, irrespective of the type of salt used (i.e. mono- or bivalent ions) and the temperature (i.e. 4°C or 20°C). Once solubilized, the PS I trimer is stable over a wide range of ion concentrations (i.e. beyond 0.5 M). A model is presented which suggests a monomer-oligomer equilibrium of PS I, but also of PS II and the cyt. b6/f-complex in the cyanobacterial thylakoid membrane. The possible physiological role of this equilibrium in the regulation of state transitions is discussed.
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    Organic acids in the rhizosphere of Banksia integrifolia L.f. (1992)
    Springer
    Plant and soil 144 (1992), S. 259-265 
    Details
    ISSN: 1573-5036
    Keywords: citric acid ; GC ; HPLC ; proteoid roots ; rhizosphere ; root exudates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Water leachates of the proteoid root layer of a mature stand of Banksia integrifolia were analysed for low molecular weight (LMW) organic acids by GC, HPLC and colorimetric techniques. Large amounts of organic acids (2500 μ g in 100 mL of leachate) were found in the proteoid root layer compared to the surrounding soil and leaf litter (∼230 μg in 100 mL of leachate). Citric acid represented approximately 50% of the total organic acids leached, malic acid approximately 18%, and aconitic acid constituted approximately 17%. Concentration of citric acid in the proteoid root layer may enhance the availability of phosphorus for plant uptake.
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    Effect of abscisic acid application on root isoflavonoid concentration and nodulation of wild-type and nodulation-mutant soybean plants (1993)
    Springer
    Plant and soil 153 (1993), S. 145-149 
    Details
    ISSN: 1573-5036
    Keywords: abscisic acid ; Glycine max ; HPLC ; isoflavonoids ; nodulation mutants ; soybean
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Isoflavonoids (daidzein, genistein, and coumestrol) are involved in induction of nod genes in Bradyrhizobium japonicum and may be involved in nodule development as well. Abscisic acid (ABA) may also impact nodulation since ABA is reportedly involved in isoflavonoid synthesis. The current study was conducted to evaluate whether ABA plays a role in differential nodulation of a hypernodulated soybean (Glycine max L. Merr.) mutant and the Williams parent. Exogenous ABA application resulted in a decrease in nodule number and weight in both lines. Isoflavonoid concentrations were also markedly decreased in response to ABA application in both inoculated and noninoculated soybean roots. The inoculation treatment itself resulted in a marked increase in isoflavonoid concentrations of NOD1-3, regardless of ABA levels, while only slight increases occurred in Williams. The nodule numbers of both soybean lines across several ABA concentration treatments were highly correlated with the concentration of all three isoflavonoids. However, differences in internal levels of ABA between lines were not detected when grown in the absence of external ABA additions. It is concluded that differential nodule expression between the wild type and the hypernodulated mutant is not likely due to differential ABA synthesis.
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    URL: http://dx.doi.org/10.1007/BF00010552
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    Taxus callus cultures: Initiation, growth optimization, characterization and taxol production (1993)
    Springer
    Plant cell, tissue and organ culture 35 (1993), S. 181-193 
    Details
    ISSN: 1573-5044
    Keywords: HPLC ; membrane rafts ; microtubule bioassay ; roots ; Taxol ; Taxus tissue eulture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Callus was induced from Taxus baccata cv. Repandens Parsons ex Rehd., T. brevifolia Nutt., T. cuspidata Sieb. & Zucc., and T. x media cvs. Hicksii and Densiformis Rehd. using different concentrations of 2,4-d-(2,4-dichlorophenoxyacetic acid), IBA (indole-3-butyric acid), or NAA α-naphthalene acetic acid in combination with kinetin. All cultures grew slowly following the first subculture, and a majority turned brown and ceased growth within the next six to twelve months. The callus cultures which lived, continued to grow very slowly for one to two years before the growth rate improved. Initiation of roots and shoot primordia-like structures occurred on some cultures maintained in the dark, and 16 h light/8 h dark, respectively. A fast-growing, habituated callus line (CR-1) derived from T. x media Rehd. cv. Hicksii was established from callus initiated in 1986. Supplementing the medium with casein hydrolysate and both fructose and glucose enhanced the growth rate. A great deal of heterogeneity was found among and within the callus, with respect to the amount of taxol produced. The callus exhibited levels of taxol ranging from 0.1 to 13.1 mg kg-1 (0.0001 to 0.0131%) on a dry weight basis. Overall, the older brown-colored callus produced more taxol than the younger pale yellow-colored callus. The presence of taxol in callus samples was established by high performance liquid chromatography, its biological activity confirmed by a microtubule-stabilizing bioassay and its structure confirmed using one-and two-dimensional 1H and 13C nuclear magnetic resonance spectroscopy.
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    URL: http://dx.doi.org/10.1007/BF00032968
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    A fluorimetric assay for determining variation of lysine in wheat gliadin proteins (1994)
    Springer
    Euphytica 76 (1994), S. 97-100 
    Details
    ISSN: 1573-5060
    Keywords: Triticum aestivum ; high performance liquid chromatography ; HPLC ; nutrition ; wheat breeding ; lysine content
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary An effective method for estimating lysine in wheat gliadin proteins could contribute to increasing lysine in wheat. Wheat gliadin proteins were separated and collected by reverse phase high performance liquid chromatography (RP-HPLC). A fluorimetric assay with o-phthalaldehyde (OPA) was used to determine the lysine content of wheat gliadin proteins. The OPA reagent reacts specifically with the amino group of lysine in protein. Twenty fractions of wheat gliadins were collected and analyzed by the fluorimetric assay. Nine of these fractions were also analyzed for lysine content by an amino acid analyzer. The results obtained from the fluorimetric assay were significantly related to the results obtained from the amino acid analyzer (R=0.93 for quadratic regression of the nine selected gliadin fractions). Lysine content of the wheat gliadins varied from 0.6 to 1.4 percent of the protein. This study determined that the fluorimetric assay could accurately estimate lysine in wheat gliadin proteins. Identification of high-lysine gliadin subunits could be implemented into a program of breeding for increased lysine in wheat.
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    URL: http://dx.doi.org/10.1007/BF00024025
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    Identification of the major chlorosomal bacteriochlorophylls of the green sulfur bacteria Chlorobium vibrioforme and Chlorobium phaeovibrioides; their function in lateral energy transfer (1993)
    Springer
    Photosynthesis research 35 (1993), S. 159-169 
    Details
    ISSN: 1573-5079
    Keywords: green sulfur bacteria ; chlorosome ; bacteriochlorophyll c ; bacteriochlorophyll d ; bacteriochlorophyll e ; HPLC ; absorption spectrum ; mass spectroscopy ; Chlorobiaceae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The chlorosomal bacteriochlorophyll (BChl) composition of the green sulfur bacteria Chlorobium vibrioforme and Chlorobium phaeovibrioides was investigated by means of normal-phase high-performance liquid chromatography. From both species a number of homologues was isolated, which were identified by absorption and 252Cf-plasma desorption mass spectroscopy. Besides BChl d, C. vibrioforme contained a significant amount of BChl c, which may provide an explanation for the previous observation of at least two spectrally different pools of BChl in the chlorosomes of green sulfur bacteria (Otte et al. 1991). C. phaeovibrioides contained various homologues of BChl e only. Absorption spectra in acetone of BChl c, d and e, as well as bacteriopheophytin e are presented. No systematic differences were found for the various homologues of each pigment. In addition to farnesol, the mass spectra revealed the presence of various minor esterifying alcohols in both species, including phytol, oleol, cetol and 4-undecyl-2-furanmethanol, as well as an alcohol of low molecular mass, which is tentatively assumed to be decenol.
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    Relations between auxin and cytokinin contents and in vitro rooting of tree Peony (Paeonia suffruticosa Andr.) (1994)
    Springer
    Plant growth regulation 15 (1994), S. 69-73 
    Details
    ISSN: 1573-5087
    Keywords: auxin ; cytokinin ; ELISA ; HPLC ; in vitro rooting ; Paeonia suffruticosa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In this work, a combined HPLC-ELISA technique was used to associate in vitro rooting capacity of tree peony micro-cuttings with contents of cytokinin and auxin; the cytokinin mainly detected corresponded to the N6-benzyladenine which had been added to the multiplication medium. Rooting capacity of explants was favoured by a preliminary accumulation of endogenous IAA only when levels of the BA absorbed from the multiplication medium had decreased. Main shoots coming from a 5-weeks subculture fulfilled these hormonal conditions and were the best microcuttings for rooting (87% rooting). Main shoots coming from shorter cycles or axillary shoots coming from a 5-weeks cycle always contained high benzyladenine levels and had a low rooting capacity (25–55% rooting). Root induction was associated with an early peak of indole-3-acetic acid followed by a 10-fold lower peak of endogenous ribofuranosyl-isopentenyladenine. Only a low and transitory accumulation of isopentenyladenine occurred during root development, and this could explain the lack of shoot development. Root development was efficient, especially in a medium containing activated charcoal, which led to an almost 3-fold decrease of IAA contents in roots.
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    Changes in the sugar content of barley anthers during culture on different carbohydrates (1990)
    Springer
    Plant cell, tissue and organ culture 22 (1990), S. 77-85 
    Details
    ISSN: 1573-5044
    Keywords: anther ; barley ; carbohydrates ; HPLC ; microspores
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The quantity of glucose liberated by an anther homogenate from nine different carbon substrates, was examined to elucidate the rate of carbohydrate breakdown by anther tissues in culture. The possible relationship between these results and development in culture was examined by extraction, and HPLC analysis of the soluble sugars from anthers cultured on medium containing one of four of the previously tested carbon substrates. Similarly, sugars from anthers subjected to one of three different inductive pretreatments, were analysed and compared with extracts from fresh anthers. The most successful carbon source in culture, when measured by fresh, and dry weight gain of the developing anthers, were the diglucoses maltose and cellobiose. Glucose was probably liberated from these diglucose substrates at a similar rate to that at which it could be utilized during the development of microspore derived structures. Pretreatments were shown to increase the glucose content of anthers, providing a pulse of the sugar at the start of culture. This effect was particularly pronounced when anthers were preincubated on a medium containing mannitol, and this type of pretreatment was found to be the most successful in promoting the development of microspore derived structures (measured by gain in fresh and dry weight) when subsequently cultured on medium containing maltose.
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    De novo purine biosynthesis in the crustacean Artemia: Influence of salinity and geographical origin (1992)
    Springer
    Journal of comparative physiology 162 (1992), S. 263-266 
    Details
    ISSN: 1432-136X
    Keywords: Metabolism ; Purine nucleotides ; De novo synthesis ; HPLC ; Crustacean, Artemia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In vivo studies of the incoporation of [U-14C]glycine into purine nucleotides have established the de novo pathway for purine biosynthesis in Artemia sp. during the early period of larval development. This pathway can be modified by the salt concentration of the incubation media. In addition, Artemia of different geographical origins may differ with respect to the detection, functionality and variability of this metabolical pathway.
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    Fluorinated anthracyclines: Synthesis and biological activity (1990)
    Springer
    Investigational new drugs 8 (1990), S. 1-6 
    Details
    ISSN: 1573-0646
    Keywords: fluorinated anthracyclines ; HPLC ; cell accumulation ; cytotoxicity ; NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract A number of fluorine containing derivatives of daunomycin and Adriamycin have been synthesised with a fluorine substituent located on the C-9 side chain. They included the p-trifluoromethyl-(4) and p-fluorobenzoate (3) esters of Adriamycin and the trifluoro-ethyl-hydrazones of Adriamycin (2) and daunomycin (1). The less polar derivatives (esters 3 and 4) appear to enter HeLa cells more readily than the polar derivatives (hydrazones 1 and 2) as indicated by the rates and extent of cellular uptake and the uptake was by facilitated diffusion. All four fluorinated derivatives were less active than their parent anthracyclines, but the difference was less pronounced when considering specific potency. The fluorinated derivatives (1–4) behaved sufficiently similar to daunomycin and Adriamycin to enable their use as fluorine probes in 19F NMR physicochemical and cellular studies of anthracyclines.
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    Structures of asparagine linked oligosaccharides of immunoglobulins (IgY) isolated from egg-yolk of Japanese quail (1993)
    Springer
    Glycoconjugate journal 10 (1993), S. 202-213 
    Details
    ISSN: 1573-4986
    Keywords: Asn-linked oligosaccharide ; quail egg-yolk ; immunoglobulin ; p-aminobenzoic acid ethyl ester ; HPLC ; glucosylated oligomannose-type oligosaccharide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Structures of the Asn linked oligosaccharides of quail egg-yolk immunoglobulin (IgY) were determined in this study. Asn linked oligosaccharides were cleaved from IgY by hydrazinolysis and labelled withp-aminobenzoic acid ethyl ester (ABEE) afterN-acetylation. The ABEE labelled oligosaccharides were then fractionated by a combination of Concanavalin A-agarose column chromatography and anion exchange, normal phase and reversed phase HPLC before their structures were determined by sequential exoglycosidase digestion, methylation analysis, HPLC, and 500 MHz1H-NMR spectroscopy. Quail IgY contained only neutral oligosaccharides of the following categories: the glucosylated oligomannose type (0.6%, Glcα1-3Glcα1-3Man9GlcNAc2; 35.6%, Glcα1-3Man7–9GlcNAc2). oligomannose type (15.0%, with the structure Man5–9GlcNAc2) and biantennary complex type with core structures of-Manα1-3(-Manα1-6)Manβ1-4GlcNAcβ1-4GlcNAc (9.9%),-Manα1-3(GlcNAcβ1-4)(-Manα1-6)Manβ1-4GlcNAcβ1-4GlcNAc (25.1%) and-Manα1-3(GlcNAcβ1-4)(-Manα1-6)Manβ1-4GlcNAcβ1-4(Fucα1-6)GlcNAc (11.4%). Although never found in mammalian proteins, glucosylated oligosaccharides (Glc1Man7–9GlcNAc2) have been located previously in hen IgY.
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    High performance liquid chromatographic screening methods for revealing the stereoselectivity of reversible interactions between ligand enantiomers and a counterpart substance (1994)
    Springer
    Chromatographia 38 (1994), S. 761-765 
    Details
    ISSN: 1612-1112
    Keywords: Chiral stationary phase (CSP) ; HPLC ; Stereoselectivity ; Reversible binding interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The stereoselectivity of the reversible binding interaction between tryptophan enantiomers and various counterpart substances (oligo- and polysaccharides, proteins) has been studied by HPLC. The properties of the “simplest” of three different experimental designs are presented. Bovine serum albumin bound to silica gel was used as the chiral HPLC stationary phase; phosphate-buffered DL-tryptophan solution was used as mobile phase. The stereoselectivity of interactions between different oligo- and macrobiomolecules and the two tryptophan enantiomers was evaluated from the areas of negative recorder deflections at the retention times of the D and L isomers of tryptophan.
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    Degradation of Synthetic Salmon Calcitonin in Aqueous Solution (1992)
    Springer
    Pharmaceutical research 9 (1992), S. 1521-1523 
    Details
    ISSN: 1573-904X
    Keywords: salmon calcitonin ; stability ; kinetics ; peptide ; degradation ; pH–rate profile ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1023/A:1015839719618
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    Peptide Stability in Drug Development. II. Effect of Single Amino Acid Substitution and Glycosylation on Peptide Reactivity in Human Serum (1993)
    Springer
    Pharmaceutical research 10 (1993), S. 1268-1273 
    Details
    ISSN: 1573-904X
    Keywords: stability ; degradation ; peptidase ; HPLC ; peptide ; glycopeptide ; glycosylation ; serum ; plasma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The determination of peptide stability in human serum (HS) or plasma constitutes a powerful screening assay for eliminating unstable peptides from further development. Herein we report on the stability in HS of several major histocompatibility complex (MHC)-binding peptides. Some of these peptides are in development for the novel treatment of selected autoimmune disorders such as rheumatoid arthritis and insulin-dependent diabetes. For most of the 1-amino acid peptides studied, the predominant degradation mechanism is exopeptidase-catalyzed cleavage. Peptides that were protected by d-amino acids at both termini were found to be more stable than predicted, based on additivity of single substitutions. In addition, N-acetylglucosamine glycopeptides were significantly stabilized, even when the glycosylation site was several amino acids from the predominant site(s) of cleavage. This indicates that long-range stabilization is possible, and likely due to altered peptide conformation. Finally, the effect of single amino acid substitutions on peptide stability in HS was determined using a model set of poly-Ala peptides which were protected from exopeptidase cleavage, allowing the study of endopeptidase cleavage pathways.
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    Chromatographic Methods for Quantitative Analysis of Native, Denatured, and Aggregated Basic Fibroblast Growth Factor in Solution Formulations (1994)
    Springer
    Pharmaceutical research 11 (1994), S. 485-490 
    Details
    ISSN: 1573-904X
    Keywords: fibroblast growth factor ; protein stability ; formulation ; HPLC ; denaturation kinetics ; fluorescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract High-performance liquid chromatography (HPLC) methods were developed for evaluating stability of human recombinant basic fibroblast growth factor (bFGF) against denaturation and aggregation in solution formulations. Re versed-phase chromatography (RP-HPLC)-insensitive to bFGF tertiary structure-was used to measure total soluble protein; heparin affinity chromatography (HepTSK) provided quantitative analysis of native bFGF species. The folding state of bFGF was determined by fluorescence spectroscopy: Tryptophan emission, which was quenched in native protein, increased upon unfolding. Slow unfolding/refolding kinetics of bFGF in 2 M guanidine hydrochloride made possible the separation of native from denatured species by size exclusion chromatography (SEC). Although the tertiary structure affected bFGF retention times, it did not change the sample recovery by SEC. These chromatographic techniques, which quantitatively measure physical and chemical changes taking place in solution formulations, can be used in future investigations of bFGF stability.
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    Phenolic acid content of soils from wheat-no till, wheat-conventional till, and fallow-conventional till soybean cropping systems (1991)
    Springer
    Journal of chemical ecology 17 (1991), S. 1045-1068 
    Details
    ISSN: 1573-1561
    Keywords: Wheat ; Triticum aestivum ; soybean ; Glycine max ; no till ; conventional till ; soil extracts ; allelopathy ; phenolic acids ; Folin & Ciocalteu's phenol reagent ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Soil core (0–2.5 and/or 0–10 cm) samples were taken from wheat no till, wheat-conventional till, and fallow-conventional till soybean cropping systems from July to October of 1989 and extracted with water in an autoclave. The soil extracts were analyzed for seven common phenolic acids (p-coumaric, vanillic,p-hydroxybenzoic, syringic, caffeic, ferulic, and sinapic; in order of importance) by high-performance liquid chromatography. The highest concentration observed was 4 μg/g soil forp-coumaric acid. Folin & Ciocalteu's phenol reagent was used to determine total phenolic acid content. Total phenolic acid content of 0- to 2.5-cm core samples was approximately 34% higher than that of the 0- to 10-cm core samples. Phenolic acid content of 0- to 2.5-cm core samples from wheat-no till systems was significantly higher than those from all other cropping systems. Individual phenolic acids and total phenolic acid content of soils were highly correlated. The last two observations were confirmed by principal component analysis. The concentrations were confirmed by principal component analysis, tions of individual phenolic acids extracted from soil samples were related to soil pH, water content of soil samples, total soil carbon, and total soil nitrogen. Indirect evidence suggested that phenolic acids recovered by the water-autoclave procedure used came primarily from bound forms in the soil samples.
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    Allelopathic compounds in leaves ofGliricidia sepium (Jacq.) kunth ex walp. and its effect onSorghum vulgare L. (1993)
    Springer
    Journal of chemical ecology 19 (1993), S. 1691-1701 
    Details
    ISSN: 1573-1561
    Keywords: Allelochemicals ; Gliricidia sepium ; Sorghum vulgare ; HPLC ; aglycone ; phenolic acids ; weed control ; root biomass ; shoot biomass ; inflorescence biomass ; grain yield ; weed biomass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Allelochemicals fromGliricidia sepium were extracted, identified, and quantified using HPLC. Fifteen toxic compounds, namely gallic acid, protocatechuic acid,p-hydroxybenzoic acid, gentisic acid,Β-resorcyclic acid, vanillic acid, syringic acid,p-coumaric acid,m-coumaric acid,o-coumaric acid, ferulic acid, sinapinic acid (trans andcis forms), coumarin, and myricetin were identified and quantified. These compounds from the plant extracts were tested on the seeds of the crop plant,Sorghum vulgare. Rate of germination of the seeds and root elongation were found to be inhibited by the various compounds of the extract. Different quantities ofGliricidia leaf mulch, viz., 400, 800, and 1200 g/m2 applied to theSorghum grown fields, were found to effectively control weeds. Mulching improved the total yield ofSorghum. Leaf manuring and mulching showed better crop yield when applied up to 800 g ofGliricidia leaf/m2. Crop yield was better in mulch-applied fields when compared to the manure-applied ones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00982301
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