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  • 1
    Electronic Resource
    Electronic Resource
    Preparation and Chromatographic Application of Macroporous Silicate in a Capillary (2000)
    Springer
    Journal of sol gel science and technology 19 (2000), S. 371-375 
    Details
    ISSN: 1573-4846
    Keywords: phase separation ; silica ; capillary column ; HPLC ; CEC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Continuous macroporous silica gel networks were prepared in a fused silica capillary, and evaluated in reversed-phase liquid chromatography. Under pressure-driven conditions, considerable dependence of column efficiency on the linear velocity of the mobile phase was observed in spite of the small size of the silica skeletons. A major source of band broadening in the pressure-driven mode was found in the A-term of van Deemter equation. The performance of the continuous silica capillary column in the electro-driven mode was much better than that in the pressure-driven mode.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008770707572
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  • 2
    Electronic Resource
    Electronic Resource
    Differential Effect of Cd2+ and Ni2+ on Amino Acid Metabolism in Soybean Seedlings (2000)
    Springer
    Biologia plantarum 43 (2000), S. 79-84 
    Details
    ISSN: 1573-8264
    Keywords: alanine aminotransferase ; aspartate aminotransferase ; cysteine ; Glycine max ; heavy metals ; HPLC ; nitrate assimilation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In 10-d-old soybean seedlings, the growth of roots and shoots was significantly inhibited at 50 and 100 μM and more Cd2+, respectively, and by 50 μM or more Ni2+. Although total protein content of roots exposed to 200 μM Cd2+ or Ni2+ was similarly decreased compared to the control, the activity of nitrate reductase was much more inhibited by Cd2+. Ni2+-treatment (200 μM) induced an accumulation of all free amino acids in roots associated with a decrease in alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities reflecting the accumulation of both alanine and aspartic acid, respectively. Cd2+-treatment (200 μM) decreased the amount of all free amino acids. In addition, cysteine which is the main amino acid consisting the phytochelatin complexes constituted about 17.5 % of total free amino acids. The activities of both ALT and AST in Cd2+-treated roots were higher than in Ni2+-treated roots suggesting higher conversion of alanine and aspartate to pyruvate and oxaloacetate. Primary leaves excised from either Cd2+ or Ni2+-treated seedlings showed similar pattern of enzyme activities as roots.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026507114354
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  • 3
    Electronic Resource
    Electronic Resource
    Gene Transfer In Vitro and In Vivo by Cationic Lipids Is Not Significantly Affected by Levels of Supercoiling of a Reporter Plasmid (2000)
    Springer
    Pharmaceutical research 17 (2000), S. 967-973 
    Details
    ISSN: 1573-904X
    Keywords: cationic lipids ; transfection ; DNA supercoiling ; HPLC ; lipofection ; gene therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. It is a common preconception that supercoiledplasmid DNA is more desirable for the transfection of cells that the relaxedform of the plasmid. This notion has led to the recommendation that aspecification for the minimum amount of plasmid in the supercoiled formshould exist in a gene therapy product. We have tested this notion byexamining the effects of the degree of supercoiling on cationiclipid-mediated gene transfer in vitro and in vivo. Methods. An ion-exchange high performance liquidchromatography (HPLC) method was developed to accurately quantitatethe relative amounts of supercoiled DNA in purified plasmid. A sample of thepurified plasmid was fully relaxed using topoisomerase. Next, the ability ofvarious levels of supercoiled plasmid to transfect mammalian cells wasmeasured. Results. This study suggests that there is no relationbetween the degree of supercoiling and lipofection efficiency. Subsequenttransfection using several different lipofection agents, different celltypes, and an in vivo model support these results. Conclusions. In considering a specification for the amountof supercoiled plasmid in a gene therapy product, it must be noted that therelaxed forms of the plasmid are no less efficient at gene delivery than thesupercoiled forms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007531405796
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  • 4
    Electronic Resource
    Electronic Resource
    Determination of the Tropospheric Hydroxyl Radical by Liquidphase Scrubbing and HPLC: Preliminary Results (2000)
    Springer
    Journal of atmospheric chemistry 36 (2000), S. 81-105 
    Details
    ISSN: 1573-0662
    Keywords: hydroxyl radical ; OH ; HPLC ; chromatography ; atmosphere ; air ; troposphere ; determination ; analysis ; air scrubbing ; scavenging ; fluorescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract A preliminary study was carried out toexamine the feasibility of measuring tropospherichydroxyl radicals (OH) by liquidphase scrubbing andhigh performance liquid chromatography (HPLC). Thepotential advantages of this approach are itssimplicity, portability, and low expense. Thesampling system employs glass bubblers to trapatmospheric OH into a buffered solution of salicylicacid (o-hydroxybenzoic acid, OHBA). Rapidreaction of OH with OHBA produces a stable fluorescentproduct, 2,5-dihydroxybenzoic acid (2,5-DHBA), whichis determined by reverse-phase HPLC and fluorescencedetection. Our preliminary field results indicatethat this method is most suitable for OH measurementsin clean tropospheric air, where interferences fromother atmospheric species appear to be negligible orminor relative to polluted air. In clean air, thesampling period is about 45–90 minutes, which yieldsa detection limit of approximately 3–6 ×105 radicalscm-3. During an OHintercomparison experiment at the Caribou samplingsite in Colorado, our liquidphase scrubber method wascompared with the ion-assisted mass spectrometry (MS)method. Our results were within the same range asthose of the ion-assisted MS method (1–5 ×106 radicals cm-3) within our precision atthat time (about ±30–50%). Preliminary testsin Pullman, WA indicated that the method might alsofunction in moderately polluted air by acidifying thescrubbing solution or by adding a scavenger tosuppress interferences. In Pullman, mid-day OHconcentrations were usually in the range of 2–20 ×106 radicals cm-3. Nighttime OHconcentrations were always low, either at or slightlyabove the detection limit.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006313021834
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  • 5
    Electronic Resource
    Electronic Resource
    Characterization of carotenes in a combination of a C18 HPLC column with isocratic elution and absorption spectra with a photodiode-array detector (2000)
    Springer
    Photosynthesis research 65 (2000), S. 93-99 
    Details
    ISSN: 1573-5079
    Keywords: absorption spectrum ; carotene ; carotenoid ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Carotenes have attracted much attention in recent years for their biological function in processes such as photosynthesis. The characterization of carotenes is difficult, however, because they consist of only carbon and hydrogen atoms, without oxygen. In the present study, we systematically examined the chemical structures of more than 30 carotenes, including most of the carotenes found in phototrophic organisms, and observed their elution order using a Novapak C18 HPLC column with simple isocratic elution. The elution order of the carotenes was C30, C40,C45 then C50. The C40 carotenes with fewer conjugated double bonds (N) had longer retention times. With respect to the end groups, the carotenes eluted in the following order: φ, Ψ, ∈ then β end groups. Furthermore, absorption spectra in the HPLC eluent used were recorded with a photodiode-array detector. A greater N value was associated with a longer absorption maximum wavelength. Since the conjugated end groups (φ and β) influenced the absorption spectra and the non-conjugated end groups (Ψ and ∈) did not, the number of conjugated end groups (zero, one and two) was clearly distinguishable. Therefore, the chemical structures of carotenes can be easily determined by a combination of the HPLC retention times and the absorption spectra.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006445503030
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  • 6
    Electronic Resource
    Electronic Resource
    Autotoxic Compounds from Fresh Alfalfa Leaf Extracts: Identification and Biological Activity (2000)
    Springer
    Journal of chemical ecology 26 (2000), S. 315-327 
    Details
    ISSN: 1573-1561
    Keywords: Alfalfa extract ; autotoxicity ; bioassay ; chlorogenic acid ; salicylic acid ; HPLC ; GC-MS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Many investigators have attempted to identify the allelochemicals in alfalfa (Medicago sativa), that cause autotoxicity. The autotoxic compounds from fresh alfalfa leaves were separated and quantified, and their biological activity was determined. Chemical separation procedures involved an 80% methanol extract of fresh alfalfa leaves, treatment with activated charcoal, microcrystalline cellulose thin-layer chromatography (MCTLC), and finally separation by Sephadex LH-20 column chromatography. The various fractions were examined further by high-performance liquid chromatography (HPLC). Preliminary identification by HPLC analysis resulted in peaks with retention times close to those of chlorogenic (m/z = 354) and salicylic acid (m/z = 138) standards, and these compounds were confirmed with GC-MS. Several other peaks remain unidentified. Chlorogenic acid occurs in relatively large amounts (0.39 mg/g) in alfalfa aqueous extracts as compared to salicylic acid (0.03 mg/g), and bioassays suggest that chlorogenic acid is involved in alfalfa autotoxicity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005466200919
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  • 7
    Electronic Resource
    Electronic Resource
    HPLC Screening and GC-MS Confirmation of Triazine Herbicides Residues in Drinking Water from Sugar Cane Area in Brazil (2000)
    Springer
    Water, air & soil pollution 118 (2000), S. 329-338 
    Details
    ISSN: 1573-2932
    Keywords: ametryn ; atrazine ; GC-MS ; HPLC ; simazine ; water
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The extensive use of chlorotriazines as selectiveherbicides in agriculture and their relatively highpersistence imply that these compounds are now presentin the environment, contaminating surface and groundwater. In European countries, United States andCanada, the drinking water ordinance demands a limitedconcentration of 0.5 μg L-1 for the sum of allpesticides and 0.1 μg L-1 with respect to eachcompound, implying on the necessity of sensitive andselective analytical methods. In the present study wedescribe two methods for the analysis of atrazine,simazine and ametryn residues in surface and groundwater collected from the Espraiado Stream watershed,Ribeirão Preto region, SP, Brazil. The HPLC methodused for sample screening was based on herbicideextraction with dichloromethane:isopropanol (9:1, v/v)followed by reversed-phase chromatography (RP-8) withdetection at 220 nm. The presence of herbicides wasconfirmed by GC-MS after ethyl acetate extraction. Atotal of 250 samples collected at different sites fromOctober 1995 to July 1996 were analyzed. Ametrynresidues were detected in 17 samples but almost alwaysat concentrations below those maximum levels recommended by international agencies of environmental control.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005147405509
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  • 8
    Electronic Resource
    Electronic Resource
    Cytokinins in pathogenesis and disease resistance of Pyrenophora teres-barley and Dreschslera maydis-maize interactions during early stages of infection (2000)
    Springer
    Mycopathologia 148 (2000), S. 87-95 
    Details
    ISSN: 1573-0832
    Keywords: Autoradiography ; barley ; cytokinins ; Dreschslera maydis ; green islands ; HPLC ; maize ; Pyrenophora teres
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Infection of Hordeum vulgare L. by Pyrenophora teresand of Zea mays by Dreschslera maydis were characterized by ‘green island’ formation, higher cytokinin levels and accumulation of metabolites in the infected areas. Higher cytokinin concentrations of the order 6-Y,Y-dimethylallylaminopurine 〉 zeatinriboside 〉 zeatin 〉dihydrozeatinriboside were detected at infection sites of susceptible hosts. By virtue of these cytokinins, infection sites may be acting as metabolic sinks helping proliferation of the pathogen. Existence of translocatory sinks at infection zones was confirmed from autoradiographic studies,where, accumulation of labeled metabolites was prominent at infection sites of susceptible hosts. Upon infection the lower cytokinin levels of resistant hosts decreased further with progress of infection. In the infected resistant hosts the concentrations of zeatin/zeatinriboside were the maximum among the four identified cytokinins. The pathogen is also capable of secreting cytokinins as evident from quantification of cytokinins in culture filtrate extracts using HPLC. Since detached leaves were used in the experiments the increase/decrease of various cytokinin levels may be attributed to pathogen influence. The increase in cytokinin levels in the susceptible host may be aiding the growth of the pathogen on one hand, while the decrease in the infected resistant host may signal the host to activate defenses against a potential pathogen at the early stage of infection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007126025955
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  • 9
    Electronic Resource
    Electronic Resource
    HPLC analysis ofArtemisia dracunculus extracts (2000)
    Springer
    Chemistry of natural compounds 36 (2000), S. 144-147 
    Details
    ISSN: 1573-8388
    Keywords: Artemisia dracunculus ; flavonoids ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Flavonoids in extracts ofArtemisia dracunculus L. are studied. The principal component is identified as pinocembrine. Pinocembrine is analyzed quantitatively using an internal standard. The uncertainties in the chromatographic measurements are estimated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02236417
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  • 10
    Electronic Resource
    Electronic Resource
    Nannochloropsis (Eustigmatophyceae) as source of commercially valuable pigments (2000)
    Springer
    Journal of applied phycology 12 (2000), S. 249-255 
    Details
    ISSN: 1573-5176
    Keywords: pigments ; ketocarotenoids ; xanthophyll cycle ; microalgae culture ; Nannochloropsis ; Eustigmatophyceae ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pigment composition and its variation with culture agewere analyzed in six strains of Nannochloropsis(Eustigmatophyceae). The capacity for accumulationof the ketocarotenoids astaxanthin and canthaxanthinwas higher in N. salina and N. gaditanathan in the other strains studied here. Theinfluence of salinity (15 to 100 practical units) onpigment production was studied in N. gaditana,where a defined pattern of variation could not befound apart from a notable increase in zeaxanthin at100‰. In cultures grown in a photobioreactor and athigh cell densities of about 109 cells mL-1,pigment production reached: 350 mg L-1 forchlorophyll a, 50 mg L-1 for violaxanthin,5 mg L-1 for canthaxanthin, 3 mg L-1 forastaxanthin. The highest contents of canthaxanthin andastaxanthin obtained in experiments with N.gaditana were 19.4 and 14.6 ng pigment (106cells)-1, respectively, which accounts for 0.7%dry weight. By means of xanthophyll cycle inductionthrough exposure of cells to high irradiance and at40 °C, conversion of violaxanthin intozeaxanthin may attain up to 70% of the violaxanthincontent, which corresponds to 0.6% dry weight. Theresults indicate that interest in Nannochloropsis as a source of valuable pigments isnot related to its capacity for single pigmentaccumulation, but the availability of a range ofpigments such as chlorophyll a, zeaxanthin,canthaxanthin and astaxanthin, each with highproduction levels.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008170915932
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  • 11
    Electronic Resource
    Electronic Resource
    Extraction of pigments and fatty acids from the green alga Scenedesmus obliquus (Chlorophyceae) (2000)
    Springer
    Aquatic ecology 34 (2000), S. 119-126 
    Details
    ISSN: 1573-5125
    Keywords: carotenoids ; chlorophyll ; GC ; HPLC ; lipids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In this paper, the efficiency of pigment and fatty acid extraction from resistant algae using Scenedesmus obliquus as an example was examined. We found that adding quartz sand and solvent to freeze-dried algal material and subsequent extraction in an ultrasound bath for 90min at −4 °C resulted in excellent extraction of these compounds. This extraction method was compared with a method regularly used for extraction of fatty acids and pigments, i.e. addition of solvents to algal material with subsequent incubation. Our extraction using the ultrasound and sand method was about twice as efficient as this method for both pigments and fatty acids. The ultrasound method is simple, extracts over 90% of the different substances in one step and conserves the relationships of pigments and fatty acids. In addition, no alteration- or breakdown products were observed with the new method. Thus, this method allows accurate quantitative extraction of both pigments and fatty acids from Scenedesmus obliquus and other algae. The method was also been found to be as effective for Cryptomonas erosa (Cryptophyceae), Cyclotella meneghiniana (Bacillariophyceae), Microcystis aeruginosa (Cyanophyceae), and Staurastrum paradoxum (Chlorophyceae, Desmidiaceae) and is thus applicable to a wide spectrum of algae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009911418606
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  • 12
    Electronic Resource
    Electronic Resource
    Validation of an HPLC method for the determination of *-dichlorobenzene and naphthalene in mothrepellents (1999)
    Springer
    Accreditation and quality assurance 4 (1999), S. 473-476 
    Details
    ISSN: 1432-0517
    Keywords: Key words Validation ; HPLC ; *-Dichlorobenzene ; Naphthalene ; Mothrepellents.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  The determination of dichlorobenzene and naphthalene in commercial repellents used in Spain has been validated. This was done using an isocratic regime, to test the reverse -phase HPLC system with acetonitrile: water 65 : 35 (v: v) as the mobile phase, at 20  °C. This technique is proposed for the modular validation of the HPLC system . The results obtained with this method show good agreement with the results provided by the manufacturers of the mothrepellents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007690050414
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  • 13
    Electronic Resource
    Electronic Resource
    Isolation, Characterization, and Stability of Positional Isomers of Mono-PEGylated Salmon Calcitonins (1999)
    Springer
    Pharmaceutical research 16 (1999), S. 813-818 
    Details
    ISSN: 1573-904X
    Keywords: calcitonin ; polyethylene glycol ; PEGylation ; peptide ; tryptic digestion ; stability ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To separate and characterize the different positional isomers of mono-PEGylated salmon calcitonins (mono-PEG-sCTs) and to evaluate the effects of the PEGylation site on the stability of different mono-PEG-sCTs in rat kidney homogenate. Methods. Mono-PEG-sCTs were prepared using succinimidyl carbonate monomethoxy polyethylene glycol (5,000 Da) and separated by gel-filtration HPLC followed by reversed-phase HPLC. To characterize PEGylated sCTs, matrix-assisted laser desorption ionization time of flight mass spectrometry (M ALDI-TOF MS) and reversed-phase HPLC of the trypsin digested samples were performed. Mono-PEG-sCTs and sCT in rat kidney homogenates were measured by column-switching reversed-phase HPLC with on-line detection of the radioiodinated samples using a flow-through radioisotope detector. Results. Three different mono-PEGylated sCTs were separated by reversed-phase gradient HPLC. From the MALDI-TOF MS analysis, the average molecular weight of mono-PEG-sCTs was confirmed as around 8650 Da. The presence of PEG moiety in the mono-PEG-sCTs was also manifested by the fact that the distance between two adjacent mass spectum lines was 44 Da which corresponds to PEG monomer unit. Tryptic digestion analysis demonstrated that these mono-PEG-sCTs are 3 positional isomers of N-terminus, Lys18- and Lys11-residue modified mono-PEGylated sCTs. The degradation half-life of these 3 positional isomers in rat kidney homogenates significantly increased in order of the N-terminus (125.5 min), Lys11- (157.3 min), and Lysl8-residue modified mono-PEGylated sCT (281.5 min) over the native sCT (4.8 min). Conclusions. Three positional isomers of mono-PEGylated sCTs were purified and characterized. Of these, the resistance to proteolytic degradation was highest for the Lysl8-residue modified mono-PEG-sCT. These studies demonstrate that the in vivo stability of PEGylated sCTs is highly dependent on the site of PEG molecule attachment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018861616465
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  • 14
    Electronic Resource
    Electronic Resource
    Pharmacokinetic Features and Metabolism of Calphostin C, A Naturally Occurring Perylenequinone with Antileukemic Activity (1999)
    Springer
    Pharmaceutical research 16 (1999), S. 1003-1009 
    Details
    ISSN: 1573-904X
    Keywords: pharmacokinetics ; Calphostin C ; HPLC ; perylenequinone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To examine the pharmacokinetic features and metabolism of calphostin C, a naturally occurring perylenequinone with potent antileukemic activity. Methods. HPLC-based quantitative detection methods were used to measure calphostin C levels in lysates of leukemic cells and in plasma of mice treated with calphostin C. The plasma concentration-time data were analyzed using the WinNonlin program. In vitro esterases and a microsome P450 preparation in conjunction with a LC-MS(API-EI) system were used to study the metabolism of calphostin C. Results. An intracellular exposure level (AUC0−6h) of 257 μM·h was achieved after in vitro treatment of NALM-6 cells with calphostin C at a 5 μM final concentration in culture medium. After intraperitoneal (i.p.) injection of a 40 mg/kg nontoxic bolus dose of calphostin C, the estimated Cmax was 2.9 μM, which is higher than the effective in vitro concentration of calphostin C against leukemic cells. Drug absorption after i.p. administration was rapid with an absorption half-life of 24.2 min and the estimated tmax was 63.0 min. Calphostin C was cleared with an elimination half-life of 91.3 min. An inactive and smaller metabolite (calphostin B) was detected in plasma of calphostin C-treated mice with a tmax of 41.3 min. Esterase (but not P450) treatment of calphostin C in vitro yielded an inactive metabolite (calphostin B) of the same size and elution profile. Conclusions. Target plasma calphostin C concentrations of potent antileukemic activity can be reached in mice at nontoxic dose levels. This pilot pharmacokinetic study of calphostin C combined with the availability of the described quantitative HPLC method for its detection in cells and plasma provide the basis for future preclinical evaluation of calphostin C and its potential as an anti-leukemic drug.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018923430094
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  • 15
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    Evaluation of the Pharmacokinetic Features and Tissue Distribution of the Potent Nonnucleoside Inhibitor of HIV-1 Reverse Transcriptase, N-[2-(2-fluorophenethyl)]-N′-[2-(5-bromopyridyl)]-thiourea (HI-240) with an Analytical HPLC Method (1999)
    Springer
    Pharmaceutical research 16 (1999), S. 1226-1232 
    Details
    ISSN: 1573-904X
    Keywords: HI-240 ; nonnucleoside inhibitor ; pharmacokinetics ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The purpose of the present study was to examine the pharmacokinetic features and tissue distribution of N-[2-(2-fluorophenethyl)]-N′-[2-(5-bromopyridyl)]-thiourea (HI-240), a novel non-nucleoside inhibitor of HIV reverse transcriptase with potent anti-viral activity against AZT-sensitive as well as multidrug-resistant HIV-1 strains. Methods. A sensitive and accurate high performance liquid chromatography (HPLC)-based quantitative detection method was established to measure concentrations of HI-240 in pharmacokinetic studies. The plasma concentration-time data were modeled by using the WinNonlin program to estimate the pharmacokinetic parameter values. Results. HI-240 had an elimination half-life of 78.3 ± 2.0 min after i.v. administration and 196.8 ± 3.1 min after i.p. administration. The systemic clearance of HI-240 was 2194 ± 61 ml/h/kg after i.v. administration and 9339 ± 1160 ml/h/kg after i.p. administration. Following i.v. injection, HI-240 rapidly distributed to and accumulated in multiple tissues with particularly high accumulation in adipose tissue, adrenal gland, and uterus+ovary. The concentration of HI-240 in brain tissue was comparable to that in the plasma, indicating that HI-240 easily crosses the blood-brain-barrier. Following i.p. injection, HI-240 was rapidly absorbed with a t1/2ka and a tmax values of less than 10 min. Following oral administration, HI-240 was absorbed with a t1/2ka of 4.2 ±1.1 min and a tmax of 95.1 ± 25.1 min. The intraperitoneal bioavailability was estimated at 23.5%, while the oral bioavailability was only 1%. Conclusions. The HPLC-based accurate and precise analytical detection method and pilot pharmacokinetic studies described herein provide the basis for advanced preclinical pharmacodynamic studies of HI-240. The ability of HI-240 to distribute rapidly and extensively into extravascular compartments and easily cross the blood-brain barrier represent significant pharmacokinetic advantages over AZT.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1014814313681
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  • 16
    Electronic Resource
    Electronic Resource
    A new approach for development of rugged sample preparation of metabolites of albendazole in cow milk (1999)
    Springer
    Microchimica acta 130 (1999), S. 155-163 
    Details
    ISSN: 1436-5073
    Keywords: Optimisation ; Taguchi method ; HPLC ; Solid phase extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Sample preparation is the critical step in analysis of residues in biological samples. The development of a ragged method is time-consuming, because a huge number of parameters must be checked. To reduce the number of experiments Taguchi's method was applied in the sample preparation of metabolites of albendazole. During the experiments 11 controllable and 7 noise factors were investigated. From the influence of controllable and noise factors on recovery and standard deviation, conditions for the sample preparation and recovery could be concluded with high accuracy and reliability.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01244922
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  • 17
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    Differential Distribution of Gonadotropin-Releasing Hormone Variants in the Brain of Hydrochaeris hydrochaeris (Mammalia, Rodentia) (1999)
    Springer
    Cellular and molecular neurobiology 19 (1999), S. 635-651 
    Details
    ISSN: 1573-6830
    Keywords: gonadotropin-releasing hormone ; HPLC ; radioimmunoassay ; mammalian ; capybara
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 1.In a previous paper we reported evidence for the presence of mGnRH- and sGnRH-like peptides in the preoptic–hypothalamic region of the capybara Hydrochaeris hydrochaeris (Montaner et al., 1998). In that study, the presence of a cGnRH-II like molecule in olfactory bulb extracts was suggested. 2.The capybara, the largest living rodent in the world, belongs to the order Hystricomorpha, which is considered to be one of the oldest groups of rodents. Some authors consider that this group is the ancestor of all remaining rodents. 3.In this study we have characterized GnRH molecular variants found in extracts from the olfactory bulbs and the mesencephalic region of capybara. These regions represent the two GnRH neuronal systems: the terminal nerve–septopreoptic and the midbrain systems. 4.An indirect method combining reverse-phase high-performance liquid chromatography (RP-HPLC) and radioimmunoassay (RIA) was used to characterize GnRH variants. The analysis of both extracts with two different RIA systems revealed three immunoreactive GnRH peaks, coeluting with mGnRH, cIIGnRH, and sGnRH synthetic standards. These results were additionally supported by serial dilution studies with specific antisera. 5.To our knowledge this the first report on the presence of three GnRH variants in the brain of an eutherian mammal. These results suggest that, similarly to other vertebrates, the expression of multiple GnRH variants may also be a common pattern in mammals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006936619129
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    The Intermolecular Disulfide Bridge of Human Glial Cell Line-Derived Neurotrophic Factor: Its Selective Reduction and Biological Activity of the Modified Protein (1999)
    Springer
    The protein journal 18 (1999), S. 585-593 
    Details
    ISSN: 1573-4943
    Keywords: Glial cell line-derived neurotrophic factor ; partial reduction ; HPLC ; chemical modification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Recombinant human glial cell line-derived neurotrophic factor has been implicated to have therapeutic potential in the treatment of neurodegenerative diseases. The mature protein is a single polypeptide of 134 amino acid residues and functions as a disulfide-linked dimer. Reduction of the protein with dithiothreitol at pH 7.0 and in the absence of denaturant showed that the single intermolecular cystine bridge was reduced preferentially. Direct alkylation of the generated free sulfhydryl group using iodoacetamide or iodoacetate without denaturant was incomplete. Unfolding the protein in 6 M guanidine hydrochloride prior to the modification showed rapid disulfide scrambling. However, the sulfhydryl-modifying reagent N-ethylmaleimide was able to label quantitatively the free cysteinyl residue in the absence of any added chaotropic agent. By a combination of peptide mapping, Edman degradation, and mass spectrometric analysis, the labeled residue was identified to be Cys101, hence verifying the location of the intermolecular disulfide bond. The modified protein behaved as a noncovalent dimer when chromatographed through a Superdex 75 column under nondenaturing conditions and was comparable in biological activity to an unmodified control sample. The results therefore indicate that the intermolecular disulfide bridge of the protein is not essential for its biological function.
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    URL: http://dx.doi.org/10.1023/A:1020607501910
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    Biosynthesis and Characterization of 4-Fluorotryptophan-Labeled Escherichia coli Arginyl-tRNA Synthetase (1999)
    Springer
    The protein journal 18 (1999), S. 187-192 
    Details
    ISSN: 1573-4943
    Keywords: Arginyl-tRNA synthetase ; 4-fluorotryptophan ; 19F NMR ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Escherichia coli 4-fluorotryptophan-substituted arginyl-tRNA synthetase was biosynthetically prepared and purified from a tryptophan auxotroph which could overproduce this enzyme. A method was developed to separate 4-fluorotryptophan from tryptophan and to determine accurately their contents in the 4-fluorotryptophan-containing proteins. It was confirmed that more than 95% of the tryptophan residues in the purified 4-fluorotryptophan-substituted arginyl-tRNA synthetase were replaced by 4-fluorotryptophan. Studies on the effect of the 4-fluorotryptophan replacement on properties of the enzyme showed that, when compared with the native enzyme, both the specific activity and the first-order rate constant of the fluorinated enzyme decreased by approximately 20% with just slightly higher K m values. CD studies, however, did not reveal any difference between the secondary structure of the native and fluorinated enzymes. In addition, thermal unfolding studies showed that the 4-fluorotryptophan replacement did not significantly affect the thermal stability of the enzyme. We may conclude that the substitution of 4-fluorotryptophan in arginyl-tRNA synthetase had no substantial effect on the structure and function of the enzyme. Finally, a preliminary study of 19F nuclear magnetic resonance spectroscopy of the fluorinated enzyme has shown promising prospect for further investigation of its structure and function with NMR.
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    URL: http://dx.doi.org/10.1023/A:1020675922382
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    Isolation and characterization of chloroplast Photosystem II antenna of spinach by reversed-phase liquid chromatography (1999)
    Springer
    Photosynthesis research 61 (1999), S. 281-290 
    Details
    ISSN: 1573-5079
    Keywords: antenna system ; chlorophyll–proteins ; HPLC ; LHC II ; Photosystem II ; spinach
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The protein components of the Photosystem II antenna system, isolated from spinach thylakoids, have been resolved by reversed-phase high performance liquid chromatography (RP-HPLC) using a butyl-silica stationary phase packed either into analytical or semi-preparative columns. Peak identification has been accomplished by a combination of various SDS–PAGE systems employing either Comassie (or silver) staining or immunological detection using polyclonal antibodies raised against LHC II and against CP29, CP26 and CP24 proteins and by aminoacid microsequence. Moreover, peak identification is consistent with the molecular masses determined by Electrospray Ionization Mass Spectrometry (HPLC-ESI-MS). The developed RP-HPLC method allows the resolution of all the protein components of the Photosystem II major Light Harvesting Complex (LHC II) and minor PS II antenna complex (CP24, CP26 and CP29) from grana membranes (BBY) and estimation of their relative stoichiometry in natural and stressed conditions, avoiding the expensive and time consuming separation procedure by sucrose-gradient ultracentrifugation and isoelectrofocusing.
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    URL: http://dx.doi.org/10.1023/A:1006397419473
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    Disruption of specific flavonoid genes enhances the accumulation of flavonoid enzymes and end-products in Arabidopsis seedlings (1999)
    Springer
    Plant molecular biology 40 (1999), S. 45-54 
    Details
    ISSN: 1573-5028
    Keywords: antibodies ; Arabidopsis ; flavonoid biosynthesis ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Polyclonal antibodies were developed against the flavonoid biosynthetic enzymes, CHS, CHI, F3H, FLS, and LDOX from Arabidopsis thaliana. These antibodies were used to perform the first detailed analysis of coordinate expression of flavonoid metabolism at the protein level. The pattern of flavonoid enzyme expression over the course of seedling development was consistent with previous studies indicating that chalcone synthase (CHS), chalcone isomerase (CHI), flavanone 3-hydroxylase (F3H), and flavonol synthase (FLS) are encoded by ‘early’ genes while leucoanthocyanidin dioxygenase (LDOX) is encoded by a ‘late’ gene. This sequential expression may underlie the variations in flavonoid end-products produced during this developmental stage, as determined by HPLC analysis, which includes a shift in the ratio of the flavonols, quercetin and kaempferol. Moreover, immunoblot and HPLC analyses revealed that several transparent testa lines blocked at intermediate steps of the flavonoid pathway actually accumulated higher levels of specific flavonoid enzymes and end-products. These results suggest that specific intermediates may act as inducers of flavonoid metabolism.
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    URL: http://dx.doi.org/10.1023/A:1026414301100
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    Chemical potential of Aphelandra sp. cell cultures (1999)
    Springer
    Plant cell, tissue and organ culture 58 (1999), S. 133-140 
    Details
    ISSN: 1573-5044
    Keywords: callus culture ; ESI-MS ; HPLC ; polyamines ; secondary metabolites ; verbascoside
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Six different callus lines and three different suspension culture lines were established from plants of two Aphelandra species (Acanthaceae). All established lines were analyzed for secondary metabolite accumulation. A discrepancy between secondary metabolites accumulated in the plants and in the cell cultures could be observed. All established Aphelandrasp. cell cultures produced verbascoside (acteoside) as the major extractable metabolite. Time course experiments were carried out to investigate the relationship between cell growth and verbascoside production. In the present study it was shown that verbascoside accumulation was growth dependent and positively related to the presence of 2,4-D in the medium. The conditions in which verbascoside represents ca. 18% of cell culture weight have been defined. Free polyamines were detected in the cell culture lines cultivated in MS liquid medium (cysteine 10 mg l-1, thiamine 1 mg l-1, 2,4-D 1 mg l-1, kinetin 0.2 mg l-1 and sucrose 30 g l-1). Putrescine and spermidine accumulated within 8 days to a maximum of 8.4 μmol g-1 of dry wt and 2.6 μmol g-1 of dry wt respectively and thereafter their concentration decreased rapidly. There was no evidence for the presence of spermine or any other type of free or conjugated polyamines in the tested cell culture lines.
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    URL: http://dx.doi.org/10.1023/A:1006363612428
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    Polycyclic Aromatic Hydrocarbons: Need for Assessment of Health Risks in India? Study of An Urban-Industrial Location in India (1999)
    Springer
    Environmental monitoring and assessment 59 (1999), S. 287-319 
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    ISSN: 1573-2959
    Keywords: BaP ; carcinogens ; GC-MS ; HPLC ; polycyclic aromatic hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract This paper reports the PAHs levels in the atmosphere of an urbanised industrial site of India. A high-resolution capillary gas chromatograph with a mass spectrometric detector (HRCGC-MS) and a high performance liquid chromatograph (HPLC) equipped with a fluorescence detector were used for the identification and quantitation of PAHs. The atmospheric levels of PAHs were higher (4.66 ng/m3 yearly average) than most of the concentrations previously reported in the literature. Indian sites were found more contaminated with potently carcinogenic: four and above ringed PAHs. Based on a good correlation between the levels of lead, vanadium, BaP and BghiP, the vehicular emission appears to be a major source of the PAHs. Further, the higher levels of observed PAHs could be attributed to the vertical distribution of the aerosols, the preference of the PAHs for the particulate phase and the greater availability of the substrate in the atmosphere for their sorption. This paper also discusses the need for development of a PAHs monitoring protocol and related health effect studies in developing countries such as India.
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    URL: http://dx.doi.org/10.1023/A:1006169605672
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    Detection of laxative abuse by urine analysis with HPLC and diode array detection (1999)
    Springer
    Pharmacy world & science 21 (1999), S. 40-43 
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    ISSN: 1573-739X
    Keywords: Laxative abuse ; Factitial diarrhea ; Chronic diarrhea ; Urine analysis ; Bisacodyl ; Bisoxatin ; Phenolphthalein ; Emodine ; Aloe‐emodine ; Rheine ; Danthron ; Picosulphate ; HPLC ; Diode array
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A simple method is proposed for analysis of stimulant laxatives and metabolites of laxatives in urine. All stimulant laxatives commercially available in Germany, Begium and the Netherlands, the diphenylmethane derivatives and the anthraquinones, were included. Chromatography was performed with a standardized isocratic HPLC system with diode array detection ('STIP'), which is commonly used in the Netherlands for toxicological screening. The method was validated by ingestion of a normal dose of the laxatives by human volunteers. In all cases the expected laxative metabolite could be detected in urine twelve hours after intake. Also urine samples of patients, suspected of laxative abuse, were analyzed.
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    URL: http://dx.doi.org/10.1023/A:1008647424809
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    No feeding on Phaeocystis sp. as solitary cells (post-bloom period) by the copepod Temora longicornis in the coastal waters of the English Channel (1999)
    Springer
    Hydrobiologia 414 (1999), S. 13-23 
    Details
    ISSN: 1573-5117
    Keywords: Phaeocystis sp. ; grazing ; copepods ; pigments ; HPLC ; English Channel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A Phaeocystis sp. (Prymnesiophyceae) bloom regularly occurs in April–May in the Eastern English Channel. In the literature, views are divided about the in situ appetence of copepods for this alga. In a study carried out in the coastal waters off the bay of Somme, at the end of the bloom, from 29 of April to 1 of May 1996, HPLC pigment analysis on both gut algal pigments and algal pigments from the water column shows that Temora longicornis adults did not feed on single cells of Phaeocystis sp. Alternatively, T. longicornis ingested diatoms and the gut content was correlated with the diatom biomass in the water. More, T. longicornis fed selectively on Dinophyceae and Cryptophyceae, which were scarcely present in the food environment. An inverse relationship was found between the concentration of Phaeocystis sp. in seawater and both gut content and abundance of young stages (CI–CIII copepodites) of T. longicornis. These results suggest an unfavourable impact of Phaeocystis sp. post-bloom on both feeding activity and distribution of T. longicornis.
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    URL: http://dx.doi.org/10.1023/A:1003899100526
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    The recovery of maleic hydrazide from processed potato products (1999)
    Springer
    Potato research 42 (1999), S. 95-99 
    Details
    ISSN: 1871-4528
    Keywords: analysis ; HPLC ; filter paper model ; Diels-Alder reaction ; 1,2-dihydro-3,6-pyridazinedione ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A method used for estimating extractable maleic hydrazide (MH) concentrations in fresh potato material, concentration range 5–17 mg kg−1, was found not to be suitable for processed potato products (10–33% recoveries) although, boiling potato pieces enhanced recovery by 20%. Each step of the determination was examined and a modified procedure developed with particular emphasis on the extraction of MH from the dried potato matrix, and the quality of the HPLC column used. Potato slices and model systems based on filter papers plus additives were used. Recoveries from fried potato slices were 74±6%. Based on the effect of glucose in reducing extractable MH recoveries, it is suggested that the remainder of the MH (20–25%) is converted into a conjugated structure on reaction with dehydrated sugar (Diels-Alder reaction).
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    URL: http://dx.doi.org/10.1007/BF02358395
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    Residues of free and bound maleic hydrazide in potato tubers (1999)
    Springer
    Potato research 42 (1999), S. 89-93 
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    ISSN: 1871-4528
    Keywords: analysis ; HPLC ; β-glucoside ; 1,2-dihydro-3,6-pyridazinedione ; Solanum tuberosum L.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The method of Vadukul (1991) for determining maleic hydrazide (MH) was modified and gave recoveries of free MH of 89%±4%. The values recorded on individual tubers ranged from 2–14 mg kg−1. Maleic hydrazide was evenly distributed throughout the tuber (peel, outer and inner flesh) but concentration increased slightly as tuber size increased. The concentration of free MH decreased from 7 to 3 mg kg−1 over the storage period of 5 1/2 months. Acid hydrolysis released substantial amounts of MH particularly from older potatoes (13 mg kg−1) compared with 6 mg kg−1 from new potatoes, implying that free MH is gradually converted to a bound form with time after treatment. No evidence was found for the presence of a β-glucoside of MH.
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    Variability of some phenolic acids in phloem of 1-year-old shoots of Scots pine trees growing with Heterobasidion annosum (Fr.) Bref. (1998)
    Springer
    Trees 12 (1998), S. 230-235 
    Details
    ISSN: 0931-1890
    Keywords: Key words Scots pine ; Phenolic acids ; HPLC ; Heterobasidion annosum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  HPLC chromatographic analyses of some phenolic acids in phloem of 1-year-old shoots sampled from 32 trees of eight Polish provenances of Scots pine (Pinus sylvestris L.) growing under conditions of annosum root [Heterobasidion annosum (Fr.) Bref.] are discussed. Considerable quantitative and qualitative differentiation was found among individual trees. The variability of trees was estimated with regard to the level of phenolic acids and correlations were established in order to assess the character of their joint occurrence in shoot phloem. In view of pathogen presence, the content of phenolic acids varies between individuals depending upon the genotype of pine, the stage of development of the disease and upon the effect of tree growth conditions.
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    URL: http://dx.doi.org/10.1007/PL00009713
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    Potential of Immobilized Artificial Membranes for Predicting Drug Penetration Across the Blood−Brain Barrier (1998)
    Springer
    Pharmaceutical research 15 (1998), S. 1270-1274 
    Details
    ISSN: 1573-904X
    Keywords: blood-brain barrier (BBB) ; drug transport ; prediction of brain uptake ; immobilized artificial membrane (IAM) ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The present study evaluates immobilized artificial membrane (IAM) chromatography for predicting drug permeability across the blood-brain barrier (BBB) and outlines the potential and limitations of IAMs as a predictive tool by comparison with conventional methods based on octanol/water partitioning and octadecylsilane (ODS)-HPLC. Methods. IAM- and ODS-HPLC capacity factors were determined in order to derive the hydrophobic indices log kIAMand log kwfor two sets of compounds ranging from very lipid soluble (steroids) to more hydrophilic agents (biogenic amines). The uptake of the compounds across the in vivoBBB expressed as brain uptake index (BUI) has been correlated with these HPLC capacity factors as well as octanol/ water partition (ClogP) and distribution coefficients (log D7.4). Results. For both test groups log kIAMcorrelates significantly with the respective log BUI of the drug (r2= 0.729 and 0.747, p 〈 0.05), whereas with log kw, log D7.4and ClogP there is only a correlation for the group of steroids (r2= 0.789, 0.659 and 0.809, p 〈 0.05) but not for the group of biogenic amines. There is a good correlation between log kIAMand log kw, ClogP or log D7.4for the group of steroids (r2= 0.945, 0.867 and 0.974, p 〈 0.01) but not for the biogenic amines. Conclusions. All physico-chemical descriptors examined in this study equally well describe brain uptake of lipophilic compounds, while log kIAMis superior over log D7.4, ClogP and log kwwhen polar and ionizable compounds are included. The predictive value of IAMs combined with the power of HPLC holds thus great promise for the selection process of drug candidates with high brain penetration.
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    URL: http://dx.doi.org/10.1023/A:1011904311149
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    Permeability of Articular Cartilage to Matrix Metalloprotease Inhibitors (1998)
    Springer
    Pharmaceutical research 15 (1998), S. 1414-1418 
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    ISSN: 1573-904X
    Keywords: cartilage permeability ; matrix metal loprotease inhibitors ; hydrophilicity ; cartilage location ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To develop an in vitro cartilage permeation model for cartilage permeability study and to evaluate the effects of molecular hydrophilicity and cartilage location on the permeability of articular cartilage to matrix metalloprotease inhibitors. Methods. An in vitro cartilage permeation model was developed and utilized to determine the permeability of articular cartilage to the matrix metalloprotease inhibitors of different hydrophilicity. Permeability coefficients were obtained by measuring the steady-state flux of the inhibitor compounds. HPLC methods were also developed and employed for the analysis of drug levels in assay media. Results. The relationship between permeability and hydrophilicity of drug molecules was examined. Results indicated that the permeability coefficient increased with increasing hydrophilicity of the molecule. Additionally, the relationship between the permeability and the location of the cartilage section within the animal joint was investigated. Our results showed that the drug molecules penetrated faster in the surface layer cartilage than in the deep layer cartilage. Conclusions. Increasing the hydrophilicity of a molecule would increase its permeability across articular cartilage. The in vitro cartilage permeation model developed could be used to rank order drug compounds according to their cartilage permeability profiles and to aid in drug selection and development.
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    Production of a hepatoprotective cerebroside from suspension cultures of Lycium chinense (1998)
    Springer
    Plant cell reports 18 (1998), S. 252-254 
    Details
    ISSN: 1432-203X
    Keywords: Key wordsLycium chinense ; Hepatoprotective cerebroside ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Suspension cultures derived from Lycium chinense Miller seedlings produced significant amounts of a hepatoprotective cerebroside. Callus was induced from the stem of aseptic seedlings of L. chinense and maintained on MS solid media supplemented with 1.0 ppm 2,4-D and 0.1 ppm kinetin. Suspension cultures were established, and the cells were grown in the same liquid media in the dark. Lyophilized cells were extracted with a combined reagent of chloroform and methanol (2:1, v/v). An aqueous suspension of the evaporated cell extract was partitioned with chloroform, and the chloroform layer was subjected to silicic acid column chromatography followed by semi-preparative reverse phase C8 high pressure liquid chromatography. The purified compound showed hepatoprotective activity comparable to that shown by silymarin, and the structure was identified as 1-O-(β-d-glucopyranosyl)-(2S,3R,4E,8Z)-2-N-2′-hydroxy-(palmitoyl)-4,8-sphingadiene on the basis of spectral data. The content of the compound in cultured cell was tenfold higher than that of the fruit of L. chinense. The biosynthesis of the compound in cultured cell systems appears to parallel cell growth.
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    Analysis of fossil pigments from algae and bacteria in meromictic Lake Fidler, Tasmania, and its application to lake management (1998)
    Springer
    Journal of paleolimnology 19 (1998), S. 1-22 
    Details
    ISSN: 1573-0417
    Keywords: fossil pigments ; meromixis ; Lake Fidler ; Tasmania ; HPLC ; Mass Spectrometry ; lake management ; algae ; bacteria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Lake Fidler is an ectogenic meromictic lake with a monimolimnion maintained by periodic incursions of brackish water from the lower Gordon River estuary. A dam across the middle reaches of the Gordon River has restricted these incursions of brackish water and meromictic stability has rapidly declined. A palaeolimnological study was carried in order to assess the historical development of meromixis and the impact of the dam on the microbiological communities in the lake. Fossil pigments in a 17 m sediment core were analysed using reverse phase high performance liquid chromatography (rp-HPLC) and mass spectrometry (MS). In addition, taphonomic studies of pigment production, deposition and degradation in the water column and surface sediments were used to identify planktonic and benthic pigment degradation processes and constrain the stratigraphic interpretation. Results comparing the pigment composition of pelagic sediment traps and littoral surface sediments indicated that the core from the centre of the lake would permit a historical reconstruction of planktonic bacterial and algal communities. Marked increases in prokaryotic pigments ca 3500 yr B.P. suggested the possible colonisation of a chemocline by phototrophic bacteria. Further changes in chlorophyll: carotenoid ratios and changes in relative abundances of both chlorophyll a and bacteriochlorophyll c derivatives also indicated that a change in the depositional environment had occurred; possibly due to altered stratification or anoxia. From this we infer the onset of either intermittent or permanent meromixis. Further increases in prokaryotic pigment abundance suggested that the present state of permanent meromixis was firmly established by 2070 ±50 14C yr B.P., and diatom analysis confirmed the development of a stable mixolimnion. High resolution studies of the top 10 cm of sediments measured pigments in mean concentrations of 15.1 ng g-1 with a mean S.D. of only 2.78 indicating little change in pigment abundance since the construction of the dam. Thus, Lake Fidler still retains most of the features of meromixis. However, evidence from nearby Lake Morrison and Sulphide Pool has shown that any further declines in meromictic stability will cause a rapid reversion to holomixis. Palaeolimnological evidence from the early stages of meromictic development of Lake Fidler suggests that such reversion to holomixis may not permanently eliminate all the microbiological communities, and that, given time, they may return and prosper with re-establishment of a suitable chemocline. These studies will guide recommendations for a management strategy to prevent the further decay of meromixis in the Gordon River lakes.
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    Chiral Discrimination of Amino Acids by an Optically Active Crown Ether Studied by HPLC, Extraction and a Liquid Membrane Transport Experiments (1998)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 30 (1998), S. 69-77 
    Details
    ISSN: 1573-1111
    Keywords: Crown ether ; amino acids ; enantioselection ; membrane transport ; chiral receptors ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A chiral crown ether incorporating a methyl α-d-mannopyranoside unit displayed pronounced enantioselection of amino acids in partition liquid chromatography experiments involving solvent systems of limited miscibility: water–ethanol–2,2,4-trimethylpentane. The same system has been used for amino acid transport across a liquid membrane containing the crown ether, and in liquid–liquid extraction experiments. Remarkable enantioselection has been noted for amino acids in all the processes studied.
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    Combining immunoassays with chromatographic and electrophoretic separation techniques — a review (1998)
    Springer
    Microchimica acta 129 (1998), S. 19-27 
    Details
    ISSN: 1436-5073
    Keywords: competitive ; non-competitive ; homogeneous ; heterogeneous ; pre-column immunoassay ; post-column immunoassay ; sandwich ; epitope ; on-line immunoassay ; off-line immunoassay ; laser-induced fluorescence ; microchip system ; HPLC ; CE ; digoxin digoxigenin ; solid phases affinity column ; urine ; plasma ; ELISA ; FAB fragments ; estrogen ; leukotriene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The combination of immunoassays with separation techniques such as chromatography and electrophoresis can provide both selectivity and sensitivity that is competitive with any method currently available for molecular analysis. Immunoassays can be carried out on-line and off-line, pre and post separation. The on-line post separation mode is the most promising for routine analysis because of the high throughput that can be achieved but also provides the greatest challenge with regard to compatibility of the interfaced systems. This paper reviews the various approaches that have been researched from a practical immunochemical point of view with emphasis on the special problems incurred with matrix compatibility for on-line post separation systems.
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    URL: http://dx.doi.org/10.1007/BF01246844
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    Changes in the photosynthetic pigments in bean leaves during the first photoperiod of greening and the subsequent dark-phase. Comparison between old (10-d-old) leaves and young (2-d-old) leaves (1998)
    Springer
    Photosynthesis research 57 (1998), S. 203-213 
    Details
    ISSN: 1573-5079
    Keywords: carotenoid ; chlorophyll b formation ; chlorophyllide a esterification ; accumulation of photosynthetic pigments ; HPLC ; protochlorophyllide a
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chlorophyll and carotenoid variations of 2-d-old and 10-d-old bean leaves (Phaseolus vulgaris var Red Kidney) were analyzed by HPLC during the first photoperiod of greening (16 h light + 8 h dark). The HPLC method used is suitable for the separation of cis- and trans-carotenoid isomers, Pchlide a and Chlide a as well as their esters. The main results are (1) before illumination the composition of the carotenoid pool is similar at the two developmental stages; (2) non-illuminated 2-d-old leaves are devoid of Pchlide a ester; (3) chlorophyll and carotenoid accumulation in 2-d-old leaves presented a lag phase twice longer than observed in 10-d-old ones; (4) Chlide a seems directly esterified to Chl a in 2-d-old leaves whereas esterification requires four steps in 10-d-old leaves and, (5) the kinetics of Chl and carotenoid accumulation are different at the two investigated developmental stages.
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    Purification of combinatorial libraries (1998)
    Springer
    Molecular diversity 4 (1998), S. 47-52 
    Details
    ISSN: 1573-501X
    Keywords: chromatography ; HPLC ; library ; purification ; SPE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract In the early days of combinatorial chemistry, much attention focused on preparation of large libraries for lead discovery. Recently, though, the focus has shifted toward smaller, more focused libraries for lead optimization. These focused libraries generally consist of individual discrete compounds. Biological assay requirements often require compounds of high purity, thus development of automated high throughput purification methods has received new attention in the past several years. This paper covers automated high throughput purification methods that have been applied to libraries of discrete compounds. Literature published through February 1998 is included. Purification methods discussed include extraction methods, scavenger methods, solid phase extraction, and preparative HPLC.
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    URL: http://dx.doi.org/10.1023/A:1009687711082
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    Analysis of Fusarium toxins in maize and wheat using thin layer chromatography (1998)
    Springer
    Mycopathologia 142 (1998), S. 107-113 
    Details
    ISSN: 1573-0832
    Keywords: Deoxynivalenol ; Fumonisin B1 ; Zearalenone ; TLC ; HPLC ; ELISA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Thin layer chromatography (TLC) methods for identifying and quantifying deoxynivalenol (DON), fumonisin B1 (FB1) and zearalenone in grain samples were compared to immunoassay (ELISA) and high performance liquid chromatography (HPLC) methods to determine the reliability of the less expensive TLC. There was a very good agreement between levels of DON measured by TLC and competitive-direct ELISA, and between levels of fumonisin B1 measured by TLC and HPLC, over a wide range of concentrations. Correlation coefficients (Pearson's) were 0.978, 0.914 and 0.953 for DON in maize, DON in wheat and FB1 in maize respectively. A lower correlation coefficient (r = 0.672) was obtained when zearalenone was quantified by TLC and HPLC. Possible reasons for this are discussed. A cost comparison of the various methods revealed that TLC was the least expensive for sample analysis. It is recommended that researchers choose which analytical method to use based upon individual considerations of cost and precision.
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    URL: http://dx.doi.org/10.1023/A:1006937720711
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    Antibacterial activity of marine-derived fungi (1998)
    Springer
    Mycopathologia 143 (1998), S. 135-138 
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    ISSN: 1573-0832
    Keywords: antibiotics ; HPLC ; marine penicillia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract A total of 227 marine isolates of ubiqituous fungi were cultivated on different media and the secondary metabolite content of the extracts (ethyl acetate/chloroform/methanol 3 : 2 : 1) characterized by HPLC. The fungi were secured from animals, plants and sediments of Venezuelan waters (0–10 m) including mangroves and lagoonal areas. The extracts were tested for antibacterial activity. A total of 7 were active towards Vibrio parahaemolyticus and 55 towards Staphylococcus aureus, representing 18 different fungal species from 8 ascomycetous genera. For 61 strains of Penicillium citrinum antibacterial activity correlated well with content of secondary metabolites as measured by HPLC. Thirteen isolates of Penicillium steckii produced very similar profiles of secondary metabolites and 6 of these had activity against either V. parahaemolyticus or S. aureus or both.
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    URL: http://dx.doi.org/10.1023/A:1006961500325
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    Automation of sample pretreatment for liquid chromatography (1998)
    Springer
    Microchimica acta 128 (1998), S. 19-29 
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    ISSN: 1436-5073
    Keywords: automation ; sample preparation ; chromatography ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The purpose of this review is to discuss the strategic problems of automating sample preparation (SP) for high performance liquid chromatography (HPLC). There is a general feeling that SP is the bottleneck of many HPLC procedures. Despite numerous reports of successful automation of SP, there are still many laboratories using manual or semiautomated SP procedures. This calls for a reevaluation of the present situation.
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    URL: http://dx.doi.org/10.1007/BF01242185
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    Free amino acid analysis of five microalgae (1998)
    Springer
    Journal of applied phycology 10 (1998), S. 131-134 
    Details
    ISSN: 1573-5176
    Keywords: Free amino acids ; HPLC ; microalgae ; Tetraselmis suecica ; Isochrysis galbana ; Thalassiosira sp. ; Skeletonema costatum ; Chaetoceros calcitrans ; cosmetology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The HPLC separation of fluorescent o-phtaldialdehyde (OPA) derivatives has been applied to the assay of free amino acids from five microalgae commonly used in aquaculture: Tetraselmis suecica, Skeletonema costatum, Chaetoceros calcitrans, Thalassiosira sp. and Isochrysis galbana, as part an assessment of their potential use in cosmetic products. Thirteen free amino acids were analyzed using High Performance Liquid Chromatography. There were considerable differences between species. However, four amino acids were responsible for more than 60% total concentration in all species: ASP, GLU, ARG and TYR; the next most important (accounting for less than 30%) were: ALA, VAL, PHE and LYS.
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    Influence of the Structure of Steroid Hormones on Their Association with Cyclodextrins: A High-Performance Liquid Chromatography Study (1997)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 27 (1997), S. 31-40 
    Details
    ISSN: 1573-1111
    Keywords: Steroid hormones ; steroids ; β-cyclodextrin ; γ-cyclodextrin ; complexation ; association constant ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The association constants of fourteen steroid hormones with β- and γ-cyclodextrin were measured in methanol-water (20 : 80 v/v) at 35 °C using the chromatographic Hummel-Dreyer method. It was found that the greatest influence on the association constants is the structural features of ring A of these compounds but the substituents of ring D also alter the complex stability to an appreciable degree. The measured association constants were considerably greater than the corresponding values measured previously in the medium containing more methanol (45 instead of 20%).
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    Tris (2,2′-bipyridyl)ruthenium(II) electrogenerated chemiluminescence in analytical science (1997)
    Springer
    Microchimica acta 127 (1997), S. 19-39 
    Details
    ISSN: 1436-5073
    Keywords: electrogenerated Chemiluminescence ; Ru(bpy) 3 2+ ; detector ; flow injection analysis ; HPLC ; biosensing ; immunoassay ; DNA probe assay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Ru(bpy) 3 2+ electrogenerated chemiluminescence (CL) has rapidly gained importance as a sensitive and selective detection method in analytical science. The Ru(bpy) 3 2+ ECL is observed when Ru(bpy) 3 3+ reacts with Ru(bpy) 3 + and yields an excited state Ru(bpy) 3 2+* . ECL emission can also be obtained when a variety of oxidants and reductants react with the reduced or oxidized forms of Ru(bpy) 3 2+ . Either the reductant or the oxidant can be treated as an analyte. The Ru(bpy) 3 2+ ECL is used as a detection method for the determination of oxalate and a variety of amine-containing analytes without derivatization in flowing streams such as flow injection and HPLC. When the ECL format is used as a detector for HPLC, unstable post-column reagent addition can often be eliminated and, the problems of both sample dilution and band broadening can be avoided because the Ru(bpy) 3 3+ species are generatedin situ in the reaction/observation flow cell. Since NADH is sensitively detected with the Ru(bpy) 3 2+ ECL, many clinically important analytes can be detected by coupling them to dehydrogenase enzymes that utilize β-nicotinamide adenine cofactors to convert NAD+ to NADH. Ru(bpy) 3 2+ -derivatives are used as CL labels for immunoassay and PCR assay with Ru(bpy) 3 2+ /tripropylamine ECL system. The Ru(bpy) 3 2+ ECL label can be sensitively determined at subpicomolar concentrations, along with an extremely wide dynamic range of greater than six orders of magnitude. Furthermore, it can eliminate disposal and lifetime problems inherent in radio immunoassays. In this paper, basic principles of the Ru(bpy) 3 2+ ECL are discussed. In addition, analytical applications of the Ru(bpy) 3 2+ ECL are illustrated with examples.
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    Chromatographic Indexes on Immobilized Artificial Membranes for Local Anesthetics: Relationships with Activity Data on Closed Sodium Channels (1997)
    Springer
    Pharmaceutical research 14 (1997), S. 1699-1705 
    Details
    ISSN: 1573-904X
    Keywords: local anesthetics ; HPLC ; immobilized artificial membrane (IAM) ; sodium channels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To elucidate the effectiveness of the different parameters for the prediction of biological activity, the n-octanol/buffer partition coefficients and theoretical calculated lipophilicity parameters of thirteen local anesthetic drugs (LAs), including two β-blockers, were compared to the affinity values for phospholipids, calculated by a recent technique. Methods. Interactions with phospholipids were measured by high performance liquid chromatography on a stationary phase made up of phospholipids, the so-called 'Immobilized Artificial Membrane' (IAM). Reference lipophilicity parameters were measured by shake-flask method between n-octanol and buffer phases. Results. Interactions with phospholipids were predicted from log P for all compounds except tocainide, which also showed additive polar extra-interactions. Moreover, when the retention on Immobilized Artificial Membrane (IAM) phase was mainly lipophilicity-based, a unique scale included the correlation between log kw IAM and log P values, for both LAs (bases) and the structurally unrelated (nonionizable and acidic) compounds previously studied. IAM interaction values for LAs were predictive of the partition measures on liposome membranes already reported in literature. The half-blocking doses for closed sodium channel, corrected for ionization at pH 7.4, were successfully correlated with the respective IAM values for eleven compounds while procaine and tetracaine, which are ester-linked compounds and have a p-amino group as well, gave more potent results than predicted by phospholipid interactions. Conclusions. The IAM chromatographic parameters were much more effective than reference lipophilicity values in describing partition on model membranes and in predicting pharmacological potency on closed sodium channels.
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    Radiation Sterilization of Formoterol (1997)
    Springer
    Pharmaceutical research 14 (1997), S. 810-814 
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    ISSN: 1573-904X
    Keywords: formoterol ; radiation treatment ; ESR spectroscopy ; dosimetry ; storage ; HPLC ; degradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. Radiation sterilization is becoming increasingly popular for the sterilization of many pharmaceutical products. We have investigated the gamma radiation induced effects on formoterol fumarate by HPLC and ESR spectroscopy. Results and Discussion. Numerical simulation of the evolution of the ESR signal versus dose was performed using linear regression, quadratic fit and power function. The shape of the dosimetric curve is linear in the range 5−30 kGy. Owing to the weak number of free radicals generated during the irradiation, the accuracy of measurements is low. For a dose of 25 kGy, discriminating irradiated from unirradiated samples is possible if the storage period is less than 250 days. The comparison between chromatographic profiles of irradiated and unirradiated samples showed minor differences. Conclusions. From our preliminary results, radiosterilization of formoterol fumarate may be technically feasible. Estimation of the irradiation dose by ESR may be possible but, due to the weak number of free radicals generated during the irradiation, the accuracy of measurements appeared low.
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    Isolation and Characterization of Major Phase I and II Metabolites of Ibuprofen (1997)
    Springer
    Pharmaceutical research 14 (1997), S. 676-680 
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    ISSN: 1573-904X
    Keywords: ibuprofen ; metabolites ; NMR ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1012125700497
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    Separation and Quantitation of Cationic Liposome Components by High Performance Liquid Chromatography with Evaporative Light-Scattering Detection (1997)
    Springer
    Pharmaceutical research 14 (1997), S. 1269-1271 
    Details
    ISSN: 1573-904X
    Keywords: cationic lipid ; HPLC ; evaporative light scattering detection ; liposome ; lipofection ; gene therapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1012131613160
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    Mass Spectrometry and reverse phase HPLC techniques for the identification of degraded fossil pigments in lake sediments and their application in palaeolimnology (1997)
    Springer
    Journal of paleolimnology 18 (1997), S. 335-350 
    Details
    ISSN: 1573-0417
    Keywords: palaeolimnology ; pigments ; massspectrometry ; HPLC ; carotenoids ; chlorophylls ; bacteriochlorophylls ; biomarkers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences
    Notes: Abstract Accurate identification of fossil pigments is essential if they are to be used as biomarker compounds in palaeolimnological studies. In recent years High Performance Liquid Chromatography (HPLC) has greatly enhanced the efficiency with which fossil pigments can be characterised and quantified. Using HPLC, undegraded pigments are typically identified through retention times, absorbance spectra and co-chromatography with authentic reference standards. However, lake sediments may also contain degraded pigments for which there are often no standards, and which may be difficult to identify using HPLC alone. In this study, we submitted HPLC fractions of fossil pigments and pigment derivatives collected from a meromictic lake in south west Tasmania, to a combination of Mass Spectrometry (MS) techniques including Electron Impact (EI) and static Liquid Secondary Ion MS (LSIMS) to identify their molecular ion characteristics and organic chemical composition. Mass Spectrometry permitted the detection of specific mass ions which were used to verify the identity of pigments and their derivatives. These included five carotenoids, chlorophyll a and derivatives, three previously described bacteriochlorophyll c derivatives with molecular weights of 770, 784, and 802, and two undescribed derivatives of bacteriochlorophyll c with molecular weights of 766 and 788. With these improved identifications we speculate on the pathways and modes of pigment degradation in the lake and asses the value of the degraded pigments as biomarkers. The use of MS permitted the identification of a greater number of signature pigments of algal and bacterial communities thus increasing the palaeolimnological value of the sediments. These methods are best applied in fossil pigment studies where there are a large number of unknown pigments and pigment degradation products, and where there are no authentic standards for co-chromatography. Practical suggestions for pigment MS are included in the discussion.
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    URL: http://dx.doi.org/10.1023/A:1007943119392
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    Enantiomere und diastereomere 2-Methoxymethyl-pyrrolidin-1-dithiocarbonsäureester (1997)
    Springer
    Monatshefte für Chemie 128 (1997), S. 881-891 
    Details
    ISSN: 1434-4475
    Keywords: 2-Methoxymethylpyrrolidine ; Carbon disulfide ; Pyrrolidine-1-dithiocarboxylates ; Crystal structure ; Diastereomers ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Formation of the 2-methoxymethyl-pyrrolidine-1-dithiocarboxylates2–4 and alkylation of2 and3 were studied. Enantiomeric and diastereomeric derivatives of4, the preparation of diastereomeric mixtures of4 by alkylation of3 in the presence of strong bases, and formation of6 by phase transfer alkylation of2 are described. The two enantiomers of 2-(4-bromophenyl)-2-oxo-ethyl 2-methoxymethylpyrrolidine-1-dithiocarboxylate2 have been characterized by X-ray analysis.
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    Determination of arsenic species in marine organisms by HPLC-ICP-OES and HPLC-HG-QFAAS (1997)
    Springer
    Microchimica acta 127 (1997), S. 195-202 
    Details
    ISSN: 1436-5073
    Keywords: arsenic speciation ; liquid chromatography ; ICP-OES ; HG-QFAAS ; marine organisms ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Separation and quantification of six arsenic species have been performed in cod, tuna and mussel samples by high performance liquid chromatography (HPLC) using inductively coupled plasma-optical emission spectrometry (ICP-OES) and hydride generation-quartz furnace atomic absorption spectrometry (HG-QFAAS) as detection techniques. It has been shown that arsenic extraction with a water-methanol (1∶1) mixture is sufficiently quantitative for the cod and tuna, in which arsenic is mainly present as arsenobetaine (about 90% of total As extracted). In contrast, only 60% of the element is extracted from the mussels and the chromatograms obtained reveal the presence of an unknown compound. Detection limits are in the μg ml−1 range for the HPLC-ICP-OES technique (quantification of arsenobetaine and arsenocholine) and in the ng ml−1 range for the HPLC-HG-QFAAS system (quantification of arsenite, arsenate, monomethylarsonic and dimethylarsinic acids).
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    Serotonin levels as a function of age inAplysia californica (1997)
    Springer
    Invertebrate neuroscience 2 (1997), S. 253-260 
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    ISSN: 1439-1104
    Keywords: Aplysia ; serotonin ; aging ; weight ; development ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The neurotransmitter serotonin (5-HT) plays an important role in a number of behaviors inAplysia californica some of which have been shown to vary with age. We were thus interested in examining the age-dependence of 5-HT inA. californica. Because animals of the same age can have very different weights, and weight alone is reliably known for wild-caught animals, we also examined the variation of 5-HT with weight. Serotonin was measured in the ring and abdominal ganglia combined, in lab-reared animals from 3 to 12 months post-hatch across a wide weight range. Serotonin increased rapidly from 4 to 6 months, and more slowly from 6 to 13 months. Serotonin scaled by soluble ganglion protein increased from 3 to 6–7 months, reached a maximum, and then decreased again. Serotonin, but not scaled 5-HT, increased significantly with weight across the whole weight range. Animals of the same weight, but different ages, had different 5-HT levels, as did young animals of the same age but different weight. Serotonin varied significantly with both age and weight, with the age-dependence being the more significant.
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    Lawsone accumulation in normal and transformed cultures of henna, Lawsonia inermis (1997)
    Springer
    Plant cell, tissue and organ culture 51 (1997), S. 83-87 
    Details
    ISSN: 1573-5044
    Keywords: Agrobacterium rhizogenes ; hairy root ; henna ; HPLC ; Lawsonia inermis ; lawsone ; micropropagation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The improvement of axillary shoot formation of Lawsonia inermis L. cultured in vitro depended on the iron concentration in the culture medium. Regenerated shoots were rooted on a hormone-free half-strength Murashige and Skoog medium (1/2 MS) before transfer to greenhouse conditions. Determination of lawsone in the plant material was investigated using a new HPLC method. The results showed that lawsone accumulation in vivo is restricted to the aerial part of the plant. In addition, the possibility of inducing lawsone biosynthesis in root cultures was studied. Hairy root cultures were established by a co-culture method using leaf segments of L. inermis and Agrobacterium rhizogenes NCIB 8196. Of several basal media tested, the production of lawsone (0.13% dry weight) was only observed in hairy roots tissues incubated in the dark and cultured in 1/2 MS or MS media.
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    Covalent Structure of Botulinum Neurotoxin Type E: Location of Sulfhydryl Groups, and Disulfide Bridges and Identification of C-Termini of Light and Heavy Chains (1997)
    Springer
    The protein journal 16 (1997), S. 787-799 
    Details
    ISSN: 1573-4943
    Keywords: Botulinum neurotoxin ; CNBr, pepsin, clostripain fragmentation ; HPLC ; SDS-PAGE separation ; sulfhydryl ; disulfide ; C-termini
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Botulinum neurotoxin (NT) serotype E is synthesized by Clostridium botulinum as an ∼150-kDa single-chain polypeptide of 1252 amino acid residues of which 8 are Cys residues [Puolet et al. (1992), Biochem. Biophys. Res. Commun. 183, 107–113]. The posttranslational processing of the gene product removes only the initiating methionine. A very narrow segment of this 1251-residue-long mature protein—at one-third the distance from the N-terminus (between residues Lys 418 and Arg 421)—is highly sensitive to proteases, such as trypsin. The single-chain NT easily undergoes an exogenous posttranslational modification by trypsin; residues 419–421 (Gly–Ile–Arg) are excised. The proteolytically processed NT is a dichain protein in which Pro 1–Lys 418 constitute the ∼50–kDa light chain, Lys 422–Lys 1251 constitute the ∼100–kDa heavy chain; Cys 411–Cys 425 and Cys 1196–Cys 1237 form the interchain and intrachain disulfide bonds, respectively; the other four Cys residues at positions 25, 346, 941, and 1035 remain as free sulfhydryl groups. The ∼150–kDa dichain NT, and separated light and heavy chains, were fragmented with CNBr and endoproteases (pepsin and clostripain); some of these fragments were carboxymethylated with iodoacetamide (with or without I4C label) before and after fragmentation. The fragments were separated and analyzed for amino acid compositions and sequences by Edman degradation to determine the complete covalent structure of the dichain type E NT. A total of 208 amino acid residues, i.e., 16.5% of the entire protein's sequence deduced from nucleotide sequence, was identified. Direct chemical identification of these amino acids was in complete agreement with that deduced from nucleotide sequence.
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    High Throughput Analysis and Purification in Support of Automated Parallel Synthesis (1997)
    Springer
    Molecular diversity 3 (1997), S. 61-70 
    Details
    ISSN: 1573-501X
    Keywords: combinatorial chemistry ; combinatorial library ; purification ; HPLC ; preparative HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Rapid reverse-phase analytical and preparative HPLC methods havebeen developed for application to parallel synthesis libraries.Gradient methods, short columns, and high flow rates allowanalysis of over 300 compounds per day on a single system, orpurification of up to 200 compounds per day on a singlepreparative system. Hardware and software modifications allowcontinuous unattended use for maximum efficiency and throughput.
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    A new method for the characterization of chemical libraries – solely by HPLC retention times (1997)
    Springer
    Molecular diversity 3 (1997), S. 253-256 
    Details
    ISSN: 1573-501X
    Keywords: analytical methods ; chemical libraries ; HPLC ; quantitative structure property relationship (QSPR)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A method has been developed for the assignment of HPLC peaks to their corresponding compounds in libraries of single compounds (parallel syntheses). The basis of the new method is the correlation of the product retention times with the different substituents in the variable positions of the molecule. The correlation is performed automatically by a new algorithm which is part of the computer program LIBFINDER. This practical, easy-to-use tool accelerates the analysis, characterization and purification of chemical libraries, without the need for expensive HPLC-MS equipment.
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    Injury-Induced Enzymatic Methylation of Aging Collagen in the Extracellular Matrix of Blood Vessels (1997)
    Springer
    The protein journal 16 (1997), S. 269-281 
    Details
    ISSN: 1573-4943
    Keywords: Protein (D-aspartyl/L-aspartyl) carboxy methyltransferase ; aging ; isoaspartyl ; HPLC ; electrophoresis ; AdoMet
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract As a result of blood vessel injury, protein D-aspartyl/L-isoaspartyl carboxyl methyltransferase (PIMT), a normally intracellular enzyme, becomes trapped within the meshwork of the vascular extracellular matrix where it can methylate substrate proteins. In this investigation we examined the distribution of such altered aspartyl-containing substrate proteins in the vascular wall. Nearly 90% of all the altered aspartyl residues were inaccessible to intracellular PIMT. Proteins of the extracellular matrix were found to be the major repository of altered aspartyl-containing polypeptides in the blood vessel wall, accounting for ∼70% of the total amount. Proteolytic cleavage of extracellular matrix proteins with cyanogen bromide (CNBr) revealed that collagens account for most of the altered aspartyl-containing proteins of the ECM. As a consequence of blood vessel injury, both type I and type III collagen along with other proteins were found to become methylated by injury-released PIMT. It is estimated that 1 cm of vein contains on the order of 5×1014 altered aspartyl residues involving between 1% and 5% of the total extracellular protein.
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    URL: http://dx.doi.org/10.1023/A:1026352908978
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    Polynuclear Aromatic Hydrocarbons (PAHs) in fish from the Red Sea Coast of Yemen (1997)
    Springer
    Hydrobiologia 352 (1997), S. 251-262 
    Details
    ISSN: 1573-5117
    Keywords: Red Sea ; PAHs ; oil pollution ; HPLC ; GC/MS ; fish ; origin ; toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A detailed analytical study using combined normal phase high pressure liquid chromatography (HPLC), gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS) of Polynuclear Aromatic Hydrocarbons (PAHs) in fish from the Red Sea was undertaken. This investigation involves a preliminary assessment of the sixteen parent compounds issued by the U.S. Environmental Protection Agency(EPA). The study revealed measurable levels of Σ PAHs (the sum of three to five or six ring parent compounds) (49.2 ng g−1 dry weight) and total PAHs (all PAH detected) (422.1 ng g−1 dry weight) in edible muscle of fishes collected from the Red Sea. These concentrations are within the range of values reported for other comparable regions of the world. Mean concentrations for individual parent PAH in fish muscles were; naphthalene 19.5, biphenyl 4.6, acenaphthylene 1.0, acenaphthene 1.2, fluorene 5.5, phenanthrene 14.0, anthracene 0.8, fluoranthene 1.5, pyrene 1.8, benz(a)anthracene 0.4, chrysene 1.9, benzo(b)fluoranthene 0.5, benzo(k)fluoranthene 0.5, benzo(e)pyrene 0.9, benzo(a)pyrene 0.5, perylene 0.2, and indeno(1,2,3-cd)pyrene 0.1 ng g−1 dry weight respectively. The Red Sea fish extracts exhibit the low molecular weight aromatics as well as the discernible alkyl-substituted species of naphthalene, fluorene, phenanthrene and dibenzothiophene. Thus, it was suggested that the most probable source of PAHs is oil contamination originating from spillages and/or heavy ship traffic. It was concluded that the presence of PAHs in the fish muscles is not responsible for the reported fish kill phenomenon. However, the high concentrations of carcinogenic chrysene encountered in these fishes should be considered seriously as it is hazardous to human health. Based on fish consumption by Yemeni‘s population it was calculated that the daily intake of total carcinogens were 0.15 µg/person/day.
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    URL: http://dx.doi.org/10.1023/A:1003048011029
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    Quantitation of fumonisins in corn by HPLC with o-phthalaldehyde postcolumn derivatization and their identification by LC/MS (1997)
    Springer
    Mycopathologia 140 (1997), S. 157-161 
    Details
    ISSN: 1573-0832
    Keywords: Fumonisins ; o-phthalaldehyde ; HPLC ; postcolumn derivatization ; LC/MS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Fumonisins B1(FB1) and B2(FB2) were isocratically separated on a fluorocarbon column without using an ion pair reagent and nonvolatile buffer during the HPLC and were detected by an o-phthalaldehyde postcolumn derivatization system using a fluorescence detector. The minimum detectable concentrations of FB1 and FB2 in corn by this system were 0.01 μg/g and 0.01 μg/g, respectively. The separated fumonisins were further identified by a directly interfaced ion trap MS using electrospray ionization. FB1 and FB2 in naturally contaminated corn were identified in the selective ion monitoring mode at concentrations of 3.75μg/g and 1.44 μg/g, respectively.
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    URL: http://dx.doi.org/10.1023/A:1006818226376
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    Structural Features of Glycera dibranchiata Monomer Hemoglobins. Primary Sequences of Monomer Hemoglobin Components II and III (1997)
    Springer
    The protein journal 16 (1997), S. 139-150 
    Details
    ISSN: 1573-4943
    Keywords: Glycera dibranchiata ; monomer hemoglobin ; primary sequence ; mass spectrometry ; HPLC ; alignments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Primary sequences for the remaining two members (GMH2, GMH3) of the group of three major monomeric hemoglobins from the marine annelid Glycera dibranchiata have been obtained. Full sequences of each 147-amino acid globin were achieved with a high degree of confidence using standard Edman technology in combination with molecular mass determinations of the intact globins and of the cyanogen bromide cleavage fragments using electrospray ionization mass spectrometry. When minor assumptions concerning Q/E identities are made these new results indicate the likely correspondence of GMG2 with the protein represented by the first Glycera dibranchiata monomer hemoglobin complete sequence [Imamura et al., (1972), J. Biol. Chem. 247, 2785–2797]. When these new sequences are combined with the previously determined primary sequence for the third major monomer hemoglobin, GMH4 [Alam et al., J. Protein Chem. (1994), 13, 151–164], it becomes clear that these three (GMG2–4) are truly distinct proteins, contrary to previous suggestions. Surprisingly, our results show that none of these three primary sequences is identical to the published sequence of the refined monomer hemoglobin crystal structure protein; however, there is a strong correspondence to the GMG2 sequence. The present sequencing results, in combination with the published GMH4 sequence, confirm the presence of a distal Leu in place of the more commonly encountered distal His in all three of the major monomer hemoglobins isolated in this laboratory and indicate that the unusual B10 Phe occurs only in GMH4. Analysis of the sequences presented here, along with comparison of amino acid content for Glycera dibranchiata monomer hemoglobins isolated from three different laboratories, and comparison of NMR results from two laboratories suggest further correspondences which unify disparate published isolations.
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    Adaptive fuzzy control of nutrients concentration in fed-batch culture of mammalian cells (1997)
    Springer
    Cytotechnology 25 (1997), S. 9-15 
    Details
    ISSN: 1573-0778
    Keywords: adaptive control ; ammonia ; antithrombin III ; BHK cells ; fed-batch culture ; fuzzy control ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract An adaptive fuzzy controller was developed to control the glucose and glutamine concentrations in the reactor constant at the desired level. The parameter values of the controller change during the cultivation according to the culture phase which was detected by the lactate concentration. Cultivations with different glucose and glutamine set point concentrations of a recombinant BHK anchorage-dependent cell line were performed in a fed-batch reactor on-line connected with an HPLC system. Glucose and glutamine concentrations were satisfactorily controlled at each set point during all cultivation periods. Ammonia had a determining effect on productivity since it inhibited cell growth and protein specific production. Ammonia production increased with an increase of glutamine or a decrease of glucose set point concentrations, indicating the importance of glucose to glutamine ratio for the optimization of productivity in mammalian cell cultures.
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    Serum Protein Binding of Nonsteroidal Antiinflammatory Drugs: A Comparative Study (1997)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 25 (1997), S. 63-77 
    Details
    ISSN: 1573-8744
    Keywords: NSAIDs ; protein binding ; serum ; unbound fraction ; binding site ; binding constant ; HPLC ; ultrafiltration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The unbound fraction in serum f u , is a critical parameter in describing and understanding the pharmacokinetics of NSAIDs. We compared f u for 6 different NSAIDs using ultrafiltration of pooled serum at pH 7.4 and 24C. Measurements covered a wide concentration range in order to define binding affinity and number of binding sites. HPLC was used to measure drug concentrations in serum and ultrafiltrate. Direct injection of ultrafiltrate and serum (diluted 250X) permitted quantitation down to approximately 70 nM for most of the NSAIDs, i.e., approximately 15–20 ng/ml. Assuming binding only to albumin, the data were fitted to a model of two classes of binding sites with dissociation constants K1 and K2. The lowest K1 (highest affinity) was found with flurbiprofen, 0.0658 μM, the highest with ketoprofen, 5.23 μM, an 80-fold difference. At low drug concentrations, f u becomes virtually constant and approaches a lower limit, $${\text{f}}_u^{\min } $$ . The following $${\text{f}}_u^{\min } $$ values were calculated: diclofenac 0.21% fenoprofen 0.25%, flurbiprofen 0.022%, ketoprofen 0.52%, naproxen 0.039%, and tolmetin 0.37%. Thus the least bound NSAID, ketoprofen, had a value 24-fold that of the most highly bound, flurbiprofen. The NSAIDs also differed widely with regard to the extent of variation in f u within the range of therapeutic concentrations, and hence with regard to their potential as displacers of other drugs.
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    Comparative HPLC analysis of seed albumins fromVicia faba andV. kalakhensis (Fabaceae) (1997)
    Springer
    Plant systematics and evolution 208 (1997), S. 1-9 
    Details
    ISSN: 1615-6110
    Keywords: Fabaceae ; Vicia faba ; V. kalakhensis ; Seed albumins ; HPLC ; taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Previously reported electrophoretic seed albumin data have shown an unexpected association ofVicia faba withV. kalakhensis. In the present work, seed albumins ofV. faba (subsp.paucijuga and subsp.faba) were compared with those ofV. kalakhensis using ionexchange (IE) and reversed-phase (RP) high-performance liquid chromatography (HPLC). Two subspecies ofV. faba displayed similar seed albumin profiles. On the other hand, seed albumin profiles ofV. faba andV. kalakhensis showed no major protein peak in common either in IE-HPLC or RP-HPLC chromatograms. The reported differences in seed albumin composition ofV. faba andV. kalakhensis are consistent with other taxonomical data showingV. faba to be genetically distant from the wild relatives.
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    Neuronal and nonneuronal taurine-like immunoreactivity in the sea pansy, Renilla koellikeri (Cnidaria, Anthozoa) (1997)
    Springer
    Cell & tissue research 288 (1997), S. 127-134 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Taurine ; Immunohistochemistry ; HPLC ; Amino acid neurotransmitters ; Renilla koellikeri (Cnidaria)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. A quantitative evaluation of putative amino acid neurotransmitters in sea pansy polyps by high-performance liquid chromatography indicates that the taurine content exceeds that of other amino acids by a 100-fold. The cellular source of this taurine was investigated by immunohistochemistry with two polyclonal antisera raised in rabbit, one against a glutaraldehyde-polylysine-taurine conjugate and the other against a succinylated ovalbumin-carbodiimide-taurine conjugate. Taurine-immunoreactive neurons were localized in a perioral subectodermal nerve net and in the zooid nerve net of the endodermal retractor muscle of the polyp mesenteries. Double labeling experiments revealed that taurine immunostaining does not colocalize with Phe–Mat–Ang–Phe –NH2 FMRFamide immunoreactivity. In addition, strong taurine immunoreactivity was found in nematocytes and other ectodermal cells, in myoepithelial cell bodies of the endoderm, and in calcareous spicule-producing cells of the colonial tissue mass. The limited distribution of neuronal taurine immunostaining to nerve nets associated with muscle systems subtending autozooid polyp retraction supports a role for taurine as a neuromuscular transmitter for this protective reflex. In contrast, the widespread distribution of taurine immunoreactivity in nematocytes and in other nonneuronal cells points to additional cellular functions of taurine, one of which may be to mediate responses to osmotic or metabolic stress.
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    Rapid and simple assay for feruloyl and p-coumaroyl esterases (1996)
    Springer
    World journal of microbiology and biotechnology 12 (1996), S. 239-242 
    Details
    ISSN: 1573-0972
    Keywords: p-coumaric acid ; ferulic acid ; HPLC ; phenolic acid esterase assay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A rapid, simple and sensitive method for detection of ferulic and p-coumaric acids using HPLC has been developed which can be used to determine the respective phenolic acid esterase activities of microorganisms. Prior concentration, purification or derivatization of the samples are not required. As little as 0.5 mg ferulic or p-coumaric acid/I could be detected and estimated in 〈 1 h. The method is specific for the two phenolic acids sice no interference by other components was observed.
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    Determination of the stoichiometry and stability constants of theβ-cyclodextrin-dextromethorphan inclusion complexes by liquid chromatography and UV spectroscopy (1996)
    Springer
    Journal of inclusion phenomena and macrocyclic chemistry 25 (1996), S. 267-281 
    Details
    ISSN: 1573-1111
    Keywords: Dextromethorphan ; β-cyclodextrin ; complex ; HPLC ; UV spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The inclosion of dextromethorphan (DMN) by β-cyclodextrin (β-CD) was studied by using chromatography, UV spectroscopy and circular dichroism methods at 25 °C, pH 7.4 and 4.2. It was found that the βCD : DMN complex has 1 : 1 stoichiometry. It is more stable at pH 7.4 than at pH 4.2. with constants respectively equal to 8000 ± 800 M−1 and 5750 ± 500 M−i, as determined by chromatography. The stability of the complex at pH 7.4 decreases as the temperature increases. From the van 't Hoff dependence the standard entropy and enthalpy changes were determined at this pH.
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    Production of thuringiensin from Bacillus thuringiensis using a net-draft-tube, modified airlift reactor (1996)
    Springer
    World journal of microbiology and biotechnology 12 (1996), S. 32-37 
    Details
    ISSN: 1573-0972
    Keywords: Bacillus thuringiensis subsp. darmstadiensis ; HPLC ; modified airlift reactor ; net-draft-tube ; thuringiensin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract A net-draft-tube, modified airlift reactor and a stirred-tank reactor were used for thuringiensin production by Bacillus thuringiensis subsp. darmstadiensis growing with various concentrations of molasses. The optimum concentration of molasses for thuringiensin production in both reactors was 15 g/l. There was a 6 h delay in sporulation in the modified airlift reactor compared with that in the stirred-tank reactor. Thuringiensin yield in the modified airlift reactor (2.2 g/l) was consequently higher than that in the stirred-tank reactor (1.1 g/l).
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    Oxidative Degradation of Antiflammin 2 (1996)
    Springer
    Pharmaceutical research 13 (1996), S. 250-255 
    Details
    ISSN: 1573-904X
    Keywords: antiflammin 2 ; oxidation ; stability ; degradation ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To study the oxidation of the methionine residue of antiflammin 2 (HDMNKVLDL, AF2) as a function of pH, buffer concentration, ionic strength, and temperature using different concentrations of hydrogen peroxide and to determine the accessibility of methionine residue to oxidation. Methods. Reversed-phase high-performance liquid chromatography (RPHPLC) was used as the main analytical method in determining the oxidation rates of AF2. Calibration curves for AF2 and the oxidation product, methionine sulfoxide of AF2 (Met(O)-3-AF2), were constructed for each measurement using standard materials. Fast Atom Bombardment Mass Spectroscopy (FABMS) was used to characterize the product. Results. Met(O)-3-AF2 was the only oxidation product detected at pH 3.0 to 8.0. The oxidation rates were independent of buffer concentrations, ionic strength, and pH from 3.0 to 7.0. However, there was an acceleration of the rates at basic pHs, and small amounts of degradation products other than Met(O)-3-AF2 were observed in this alkaline region. Conclusions. Oxidation of methionine in AF2 does not cause the biological inactivation reported by other laboratories since this drug is relatively stable under neutral conditions in the absence of oxiding agent.
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    Oxidation of Human Insulin-like Growth Factor I in Formulation Studies: Kinetics of Methionine Oxidation in Aqueous Solution and in Solid State (1996)
    Springer
    Pharmaceutical research 13 (1996), S. 1252-1257 
    Details
    ISSN: 1573-904X
    Keywords: hIGF-I ; oxidation ; methionine ; HPLC ; kinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The aim of this work was to study the kinetics of oxidation of methionine in human Insulin-like Growth Factor I (hIGF-I)1 in aqueous solution and in the solid state by the aid of quantification of oxygen. Methods. The oxidized form of hIGF-I was characterized by tryptic peptide analysis, RP-HPLC and FAB-MS and quantified by RP-HPLC. The oxygen content was quantified polarographically by a Clark-type electrode. Results. Second-order kinetics with respect to amount of protein and dissolved oxygen was found to be appropriate for the oxidation of methionine in hIGF-I. The rate constants ranged from 1 to 280 M−1 month−l and had an activation energy of 95 (+/−4) kJ/mole. Light exposure, storage temperature and oxygen content were found to have a considerable impact on the oxidation rates. No significant difference in reaction rates was found for the oxidation of hIGF-I in aqueous solution or in the solid state. A method for decreasing the oxygen content in aqueous solution without purging is described. Conclusions. Polarographic quantification of dissolved oxygen makes it possible to establish the kinetics for oxidation of proteins. The oxidation of methionine in hIGF-I appears to follow second-order kinetics.
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    Study of precise pigment composition of photosystem 1-type reaction centers by means of normal-phase HPLC (1996)
    Springer
    Journal of plant research 109 (1996), S. 223-230 
    Details
    ISSN: 1618-0860
    Keywords: Bacteriochlorophyllg′ ; Chlorophylla′ ; Green sulfur bacteria ; Heliobacteria ; HPLC ; PS1
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Based on precise pigment analyses of a series of photosystem (PS) 1-type plants, a novel hypothesis is proposed that chiorophyll (Chl)a′ and bacteriochlorophyll (BChl)g′, the 132-epimers of Chla and BChlg, constitute the primary electron donors of PS1 and heliobacteria, respectively. Interestingly PS 1-type reaction centers do not have (B) Pheo but have Chl a-like pigments as primary electron acceptors.
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    Effects of prolonged darkness on the relative pigment content of cultured diatoms and green algae (1996)
    Springer
    Aquatic sciences 58 (1996), S. 241-252 
    Details
    ISSN: 1420-9055
    Keywords: HPLC ; chlorophylls ; phaeopigments ; carotenoids ; xanthophylls
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract To determine some of the environmental effects that influence the relative proportions of pigments in algae, high pressure liquid chromatographic (HPLC) analysis was employed to determine the relative amounts of common photosynthetic pigments in batch cultures of the diatoms,Fragilaria crotonensis andThalassiosira pseudonana, and the green algae,Scenedesmus abundans, andHaematococcus pluvialis, illuminated for 12 hours each day. Similar analyses were conducted in five-day experiments during which cultures ofF. crotonensis andS. quadricauda were kept in continuous darkness. Comparing the results to those for controls continuing to receive the daily illumination indicated that the diatoms and green algae react similarly to light deficiency. The relative amounts of the main accessory pigment in the diatoms, fucoxanthin, and that in the green alga, apparently lutein, decreased as a reaction to a lack of illumination, while the total chlorophyll level in algae of both groups remained nearly constant. Quantitative differences induced by the experimental conditions were considerably less that those observed among different species of diatom or among the different green algae, however. Finally, cultures ofS. quadricauda were analyzed and then kept for 43 days without the addition of any nutrients. A proportion of the culture was kept for this period in perpetual darkness while another continued to receive 12 hours of illumination. The results show that considerable changes occur as the cultures age, and that these changes occur more slowly in the darkness. Some consequences of these findings for phytoplankton production studies based on analyses of photosynthetic pigments are discussed.
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    Detection of genetic diversity using RAPD-PCR and sugar analysis in watermelon [Citrullus lanantus (Thunb.) Mansf.] germplasm (1996)
    Springer
    Theoretical and applied genetics 92 (1996), S. 719-725 
    Details
    ISSN: 1432-2242
    Keywords: RAPD-PCR ; HPLC ; Watermelon ; Citrullus lanantus (Thunb.) Mansf. ; Phenogram
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract RAPD (random amplified polymorphic DNA) markers generated by 15 arbitrary decamers were used to determine the frequency of DNA polymorphism in 39 watermelon [Citrullus lanantus (Thunb.) Mansf.] germplasms. Of the 15 primers tested, all except 1 (primer 275) directed the amplification of polymorphic products. A total of 162 amplification products were generated across all 39 genotypes. Among the 162 fragments, 35 (21%) appeared to be reliable polymorphic markers. The mean value by marker difference in this comparison was 0.24, and the highest, 0.69. Eight RAPD markers could be utilized in the unique variety discrimination 8 watermelon genotypes. From the phenograms constructed by UPGMA based on the comparison of RAPD markers, four clusters were resolved. Each group was also characterized and identified with morphological and genetic characteristics for each genotype. The free sugars of the edible parts of watermelons were analyzed by HPLC (high-performance liquid chromatography). Results from the phylogenetic analysis of band sharing data were consistent with sweetness as measured by HPLC. In conclusion, RAPD assays can be used for providing alternative markers for identifying genotypes and quantitative characteristics in watermelon.
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    Detection of genetic diversity using RAPD-PCR and sugar analysis in watermelon [Citrullus lanantus (Thunb.) Mansf.] germplasm (1996)
    Springer
    Theoretical and applied genetics 92 (1996), S. 719-725 
    Details
    ISSN: 1432-2242
    Keywords: Key words RAPD-PCR ; HPLC ; Watermelon ; Citrullus lanantus (Thunb.) Mansf. ; Phenogram
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  RAPD (random amplified polymorphic DNA) markers generated by 15 arbitrary decamers were used to determine the frequency of DNA polymorphism in 39 watermelon [Citrullus lanantus (Thunb.) Mansf.] germplasms. Of the 15 primers tested, all except 1 (primer 275) directed the amplification of polymorphic products. A total of 162 amplification products were generated across all 39 genotypes. Among the 162 fragments, 35 (21%) appeared to be reliable polymorphic markers. The mean value by marker difference in this comparison was 0.24, and the highest, 0.69. Eight RAPD markers could be utilized in the unique variety discrimination 8 watermelon genotypes. From the phenograms constructed by UPGMA based on the comparison of RAPD markers, four clusters were resolved. Each group was also characterized and identified with morphological and genetic characteristics for each genotype. The free sugars of the edible parts of watermelons were analyzed by HPLC (high-performance liquid chromatography). Results from the phylogenetic analysis of band sharing data were consistent with sweetness as measured by HPLC. In conclusion, RAPD assays can be used for providing alternative markers for identifying genotypes and quantitative characteristics in watermelon.
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    Certain withanolides from Iochroma gesnerioides antagonize ecdysteroid action in a Drosophila melanogaster cell line (1996)
    Springer
    Entomologia experimentalis et applicata 80 (1996), S. 415-420 
    Details
    ISSN: 1570-7458
    Keywords: antagonist ; bioassay ; ecdysteroid ; HPLC ; steroid hormone receptor ; withanolide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Sixteen withanolides isolated from Iochroma gesnerioides (Kunth) Miers (Solanaceae) have been assessed for their activities as ecdysteroid agonists and antagonists. None of the compounds showed any agonistic activity, but several showed significant antagonistic activity. With a 20-hydroxyecdysone concentration of 5 × 10−8 M, the ED50 values for 2,3-dihydro-3ξ-methoxywithaferin A, 2,3-dihydro-3ξ-methoxywithacnistine, 2,3-dihydro-3ξ-methoxyiochromolide and 2,3-dihydro-3ξ-hydroxywithacnistine are 3.5 × 10-5 M, 1 × 10−5 M, 5 × 10−6 M and 2.5 × 10−6 M, respectively.
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    Pharmacological model of catecholamine depletion in the hypothalamus of fetal and neonatal rats and its application (1996)
    Springer
    Cellular and molecular neurobiology 16 (1996), S. 617-624 
    Details
    ISSN: 1573-6830
    Keywords: catecholamines ; hypothalamus ; development ; uptake ; α-methyl-m-tyrosine ; 6-hydroxydopamine ; HPLC ; rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary 1. The present study aimed to develop a pharmacological model of catecholamine (CA) depletion in the hypothalamus during the period of its morphofunctional development, i.e. in fetal and neonatal rats of both sexes. 2. In the first series of experiments, pregnant females and, hence, fetuses were systemically treated daily from the embryonic day (E) 13 to E20 with the inhibitor of the CA synthesis α-methyl-m-tyrosine. The CA concentrations were subsequently measured in the fetal hypothalamus at E21 by high performance liquid chromatography with electrochemical detection (HPLC-ED). In the second series of experiments, neonatal rats were injected with neurotoxin, 6-hydroxydopamine and/or α-methyl-m-tyrosine daily from the 2nd postnatal day (P2) to P10. 3. The HPLC-ED assay of hypothalamic catecholamines (CA's) at E21 and P11 showed that both in fetuses and neonates, α-methyl-m-tyrosine caused more than 50% depletion of hypothalamic noradrenaline and adrenaline, while the dopamine (DA) level remained unchanged. The combined treatment of neonatal rats with α-methyl-m-tyrosine and 6-hydroxydopamine resulted additionally in a 25% decreased level of DA. 4. The influence of CA deficiency on the developing hypothalamic CA system was further evaluated by measuring [3H]DA uptake by nervous tissuein vitro. 5. The CA deficiency caused a 50% drop of [3H]DA uptake by the hypothalamic tissue in treated fetuses suggesting a stimulating effect of CA's on the early development of the CA system. In pharmacologically treated neonatal rats [3H]DA uptake remained at the control level showing no influence of the CA deficiency on the developing CA system after birth. 6. The usefulness of the proposed pharmacological model for studying of CA influence on differentiating hypothalamic target neurons is discussed.
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    URL: http://dx.doi.org/10.1007/BF02151900
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    Quantitation of combinatorial libraries of small organic molecules by normal-phase HPLC with evaporative light-scattering detection (1996)
    Springer
    Molecular diversity 1 (1996), S. 247-258 
    Details
    ISSN: 1573-501X
    Keywords: Quantitation ; Combinatorial library ; HPLC ; ELSD ; External standard ; Normal-phase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The advantages of evaporative light-scattering detection over UV detection for the quantitation of combinatorial libraries composed of small organic compounds by HPLC are described. The detector's response is independent of the sample chromophore, which makes it well-suited to chromatographie analyses of mixtures of dissimilar solutes. Thus, HPLC with evaporative light-scattering detection offers the potential for reducing false positive or false negative results in screening assays, because of its ability to detect the presence of impurities that absorb poorly in the UV (e.g., those impurities originating from the polymeric support). Furthermore, the evaporative light-scattering detector exhibits a nearly equivalent response to compounds of similar structural class. Hence, rapid quantitation of compound libraries may be carried out with the use of a single external standard. For example, the quantitation errors, based on a single external standard, for a series of steroids, hydantoins, and BOC- and Fmoc-protected amino acids by normal-phase HPLC with evaporative light-scattering detection average approximately ± 10%. The application of the evaporative light-scattering detector to the quantitation of low-level sample impurities and the detector's compatibility with gradient elution are also described.
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    URL: http://dx.doi.org/10.1007/BF01715529
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    Quantification of contact oviposition stimulants for black swallowtail butterfly,Papilio polyxenes, on the leaf surfaces of wild carrot,Daucus carota (1996)
    Springer
    Journal of chemical ecology 22 (1996), S. 2341-2357 
    Details
    ISSN: 1573-1561
    Keywords: Papilio polyxenes ; Papilionidae ; Daucus carota ; Apiaceae ; oviposition ; leaf surface ; contact chemoreception ; HPLC ; flavonoid glycosides ; chlorogenic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Ovipositing black swallowtail butterflies,Papilio polyxenes, make their final host-selection decisions on the basis of compounds present on the leaf surface. Little information is available, however, on the chemistry of leaf surfaces. The purpose of this study was to develop a technique to extract and quantify the concentrations of compounds from the leaf surfaces ofDaucus carota, one of the main host species forP. polyxenes, with particular reference to compounds already identified as contact oviposition stimulants, namelytrans-chlorogenic acid (CA) and luteolin-7-O-(6″-O-malonyl)-β-d-glucopyranoside (L7MG), as well as its degradation product luteolin-7-glucoside (L7G). Plant surfaces were extracted by dipping leaves sequentially in pairs of solvents: (1) CHCl3-MeOH, (2) near-boiling H2O, (3) CHCl3-near-boiling H2O, and (4) CH2Cl2-CH2Cl2. The resulting extracts were fractionated and analyzed using high-performance liquid chromatography. The leaf-surface concentrations of each compound were calculated using regressions relating leaf surface area to leaf weight that were obtained from measurements of field-collected carrot plants. All four methods removed the three compounds from carrot leaf surfaces, but the solvent systems differed in effectiveness. The chloroform-near-boiling water solvent system performed better than the other solvent combinations, but not significantly so. This system also extracted the highest number of polar, UV-absorbing compounds. Methylene chloride was significantly less efficient than the other methods. An additional test confirmed that the chloroform-near-boiling water method removed compounds from the surface alone and probably not from the apoplast or symplast. Surface concentrations of CA (up to 600 ng/cm2 leaf surface) were substantially greater than those of the two flavonoid compounds. No clear seasonal trend in concentrations was evident from the limited number of sampling dates.
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    URL: http://dx.doi.org/10.1007/BF02029551
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    Determination of two sites of automethylation in bovine erythrocyte protein (d-aspartyl/l-isoaspartyl) carboxyl methyltransferase (1996)
    Springer
    The protein journal 15 (1996), S. 115-122 
    Details
    ISSN: 1573-4943
    Keywords: Protein methylation ; protein repair ; aging ; MALDI mass spectrometry ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Protein (d-aspartyl/l-isoaspartyl) carboxyl methyltransferase (PCM, E.C. 2.1.1.77) was previously shown to be enzymatically methyl esterified in an autocatalytic manner at altered aspartyl residues; methyl esters are observed in a subpopulation of the enzyme termed theαPCM fraction [Lindquist and McFadden (1994),J. Protein Chem. 13, 23–30]. The altered aspartyl sites serving as methyl acceptors inαPCM have now been localized by using proteolytic enzymes and chemical cleavage techniques in combination with matrix-assisted laser desorption/ionization (MALDI) mass spectrometry to identify fragments of the [3H]automethylated enzyme that contain a [3H]methyl ester. Methylation was positively identified at positions Asn188 and Asp217 in the enzyme sequence, a consequence of the spontaneous alteration of these sites tol-isoaspartyl ord-aspartyl sites and their methylation by active PCM molecules. The identification of more than one site of automethylation shows thatαPCM is not a homogeneous population of damaged PCM molecules, but rather a complex population of molecules with a variety of age-altered damage sites.
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    URL: http://dx.doi.org/10.1007/BF01886817
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    DSP toxin contents inDinophysis fortii and scallops collected at Mutsu Bay, Japan (1996)
    Springer
    Journal of applied phycology 8 (1996), S. 509-515 
    Details
    ISSN: 1573-5176
    Keywords: ADAM ; Dinophysis fortii ; dinophysistoxin-1 ; DSP ; HPLC ; okadaic acid ; scallop
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cell densities of toxic phytoplankton species responsible for diarrhetic shellfish poisoning (DSP) were monitored at a sampling site in Mutsu Bay, Japan, in 1995.Dinophysis fortii almost completely dominated the toxic phytoplankton community. Okadaic acid (OA) and dinophysistoxin-1 (DTX1) contents in bothD. fortii cells and midgut glands of scallops collected at the same sampling site were determined by HPLC — fluorometry. DTX1 was detected fromD. fortii and scallops. The contents of DTX1 inD. fortii changed markedly during the experimental periods (5–252 pg cell−1). The highest concentration of DTX1 in the midgut glands of scallops coincided with the period of relatively high cell densities ofD. fortii with the highest content of DTX1 (252 pg cell−1). The results demonstrate that toxin content in the cells is an important factor affecting the toxicity of shellfish.
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    URL: http://dx.doi.org/10.1007/BF02186329
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    The use of ergosterol in the pathogenic fungusBipolaris sorokiniana for resistance rating of barley cultivars (1996)
    Springer
    European journal of plant pathology 102 (1996), S. 883-889 
    Details
    ISSN: 1573-8469
    Keywords: fungal pathogen ; Hordeum vulgare ; HPLC ; HPLC-MS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Ergosterol content in the plant pathogenic fungusBipolaris sorokiniana was determined in different matrices including mycelium, spores, culture filtrate and infected barley leaves. Ergosterol was extracted with methanol, hydrolysed with KOH and quantified by reverse phase high performance liquid chromatography (HPLC). Our procedure was used to study how the ergosterol concentration ofB. sorokiniana varied due to fungal age and nutrient availability when growing in liquid medium. It was found that the ergosterol content decreased with fungal age. The decrease was not due to leakage. It was also found that a change to a less nutrient-rich medium caused an increase in ergosterol content whereas a change to a rich medium led to a decrease. The procedure was also used for quantification of fungal infections in complex matrices (e.g. leaves). The development of fungal infection in barley leaves was followed during 10 days. Visual grading of leaf spots was also compared to ergosterol content in three varieties of barley. The ergosterol content in the leaves increased exponentially until day 7, and the grading of the leaf spots was correlated to the ergosterol content. Our results show that, despite a great variation, ergosterol may be used as a biomarker to detect and quantify fungal infections in a given matrix.
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    URL: http://dx.doi.org/10.1007/BF01877059
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    Preparation and properties of sorbents based on silica gel containing covalently linked fullerene C60 (1996)
    Springer
    Russian chemical bulletin 45 (1996), S. 768-770 
    Details
    ISSN: 1573-9171
    Keywords: immobilized fullerenes ; silica gel ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Sorbents containing 10–12 % fullerene C60 were prepared by the reaction of C60 with γ-aminopropylsilica gel. C60-Silica gel possesses good chromatographic properties for the separation of aromatic, nitro, and heterocyclic compounds in the regimes of normal and reversed-phase HPLC.
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    URL: http://dx.doi.org/10.1007/BF01431294
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    Triterpenoids fromAbies species 19. (22Z)-3α-Hydroxy-17,14-fridolanosta-7,14,22,24-tetraen-26,23-olide, a new lactone from the needles of the Siberian fir (1996)
    Springer
    Russian chemical bulletin 45 (1996), S. 2651-2653 
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    ISSN: 1573-9171
    Keywords: triterpenoids ; lactones ; two-dimensional NMR spectroscopy ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A new triterpenoid lactone with a reported rearranged lanostane skeleton was isolated from the neutral fraction of the extract from the needles of Siberian fir. Its structure was established on the basis of chemical transformations and NMR spectra using two-dimensional (COSY, COLOC) NMR spectroscopy.
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    URL: http://dx.doi.org/10.1007/BF01431134
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    Production of fusaric acid byFusarium oxysporum (1996)
    Springer
    Potato research 39 (1996), S. 79-83 
    Details
    ISSN: 1871-4528
    Keywords: mycotoxin ; pathogens ; HPLC ; extraction ; culture filtrates ; potatoes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The aim of the study was to determine whether isolates ofFusarium oxysporum Schlecht. produce fusaric acid in culture and whether mycelial growth can be used as a measurement of fusaric acid production. Three isolates produced significant levels of fusaric acid in culture filtrate, the maximum concentration being reached after 18 days, whereafter it remained constant. Mycelial growth could not be used to measure or estimate the production of fusaric acid. Growth curves from specific isolates could be used to determine the concentration of fusaric acid in culture filtrate after specific lengths of time.
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    URL: http://dx.doi.org/10.1007/BF02358209
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    Circadian changes in melatonin in the nervous system and hemolymph of the cabbage looper moth, Trichoplusia ni (1995)
    Springer
    Journal of comparative physiology 176 (1995), S. 761-771 
    Details
    ISSN: 1432-1351
    Keywords: Biogenic amines ; HPLC ; Trichoplusia ni ; Circadian rhythm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Quantitative levels of melatonin and 5-hydroxytryptamine were measured over the scotophase in the protocerebrum, subesophageal ganglion, optic lobes, thoracic ganglia, and hemolymph of adult male cabbage looper moths, Trichoplusia ni, using HPLC with electrochemical detection. Melatonin levels were very low (s 〈 1 pmol) or undetectable during the photophase, but increased in all tissues during the dark. Lowest mean levels in the dark were observed in the optic lobes (0.3 to 0.7 pmols). Maximal mean levels in the protocerebrum (5.2 pmols) occurred in the early part of the scotophase, but in all other tissues (2.8 in the subesophageal ganglion; 9.5 in thoracic ganglia) and hemolymph (18 pg/μl) maximal mean levels were observed later in the dark. Levels of 5-hydroxytryptamine in each tissue, in contrast, were higher than melatonin levels in the photophase, and in the protocerebrum and thoracic ganglia decreased during the dark, but in the optic lobes and subesophageal ganglion remained unchanged. Further, decreases in 5-hydroxytryptamine during the dark were significantly lower than the increased levels of melatonin, suggesting that active synthesis of 5-hydroxytryptamine was occurring. In a second experiment, when measured from individuals in three different photoperiods (6∶18, 12∶12, 18∶6 light∶dark) maximum mean melatonin levels in the brain (protocerebral and subesophageal ganglia) peaked within the first 1.5 h of the dark and remained at measurable levels for the duration of the dark. In a third experiment, levels of melatonin in the brain and thoracic ganglia displayed rhythmicity in continuous dark conditions but not in continuous light, when compared with profiles obtained in a normal light ∶ dark regime.
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    URL: http://dx.doi.org/10.1007/BF00192624
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    Dose-Dependent Pharmacokinetics of Warfarin in Healthy Volunteers (1995)
    Springer
    Pharmaceutical research 12 (1995), S. 1874-1877 
    Details
    ISSN: 1573-904X
    Keywords: warfarin ; human ; dose-dependent pharmacokinetics ; saturable tissue binding ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. To examine the pharmacokinetics of warfarin after administration of single oral doses (2, 5, and 10 mg) to healthy male volunteers. Methods. A sensitive reverse-phase HPLC method was used to quantify warfarin plasma concentrations as low as 6 ng/ml. Blood samples were collected for up to 120 hours following administration of these doses. Results. As the dose decreased from 5 to 2 mg, the apparent volume of distribution (V/F) increased from 12 to 21 liters and the terminal half-life (t1/2) increased from 47 to 71 hours. Oral clearance remained unchanged over the examined dose range. These apparent dose-dependent changes in warfarin's t1/2 and V/F may be due to saturable tissue binding of this drug. It appears that a previously undetected and prolonged terminal phase may exist but can not be adequately characterized with the 120-hour sampling interval. To evaluate this long t1/2, a follow-up study was conducted to examine warfarin's pharmacokinetics for up to 21 days following a 10-mg dose. The prolonged terminal phase started to become apparent when plasma levels declined to less than 100 ng/ml. The t1/2 of this terminal phase was determined to be approximately one week. Conclusions. This is the first report that documents the dose-dependent pharmacokinetics of warfarin and the previously unreported long t1/2 of one week for warfarin in humans.
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    URL: http://dx.doi.org/10.1023/A:1016223418652
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    Metabolism of Dynorphin A 1-13 in Human Blood and Plasma (1995)
    Springer
    Pharmaceutical research 12 (1995), S. 1165-1170 
    Details
    ISSN: 1573-904X
    Keywords: dynorphin Al-13 ; opioid peptides ; metabolism ; pharmacokinetics ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. A detailed investigation of the metabolic routes and rates of Dyn A1-13 in human blood and plasma was performed. Methods. Human plasma was incubated at 37°C with dynorphin A 1-13 (Dyn Al-13, 15-20 µM). The generated dynorphin fragments were separated by a new ion-pair chromatographic method and identified by matrix assisted laser desorption mass spectroscopy. The kinetic behavior of parent compound and metabolites was evaluated in the absence and presence of enzyme inhibitors. Results. The major plasma metabolites of Dyn Al-13 were Dyn A1-12, A2-12, A4-12 and A4-8. Further metabolites were Dyn A2-13, A3-13, A3-12, A5-12, A6-12, A7-12, Al-10, A2-10, A2-8 and A3-8. At 37°C, Dyn Al-13 had a half-life of less than one minute in plasma and blood. Plasma half-lives of major metabolites ranged between 0.5 and 4 min. Inter-and intra-individual differences in healthy volunteers were 30% (c.v.). Dyn Al-13 is mainly metabolized by carboxypeptidases to Dyn Al-12 (80%) and by aminopeptidases to Dyn A2-13 (15%). Dyn A1-12 and Dyn A2-13 are predominantly converted into Dyn A2-12 (67% of Dyn Al-13). Subsequent metabolic steps yield Dyn A3-12 (16%), Dyn A4-12 (37%) and Dyn A4-8 (33%). Aminopeptidases generate Dyn A2-12, A3-12, A4-12, A5-12. ACE metabolizes Dyn Al-12 (19%), A2-12 (33%), A3-12 (34%) and A4-12 (46%). Bestatin-sensitive endopeptidases (possibly endopeptidase 24.11) metabolize 30% of Dyn A2-12. Dyn A4-8 is formed via Dyn A4-12 (23% of Dyn A4-12) and Dyn A2-10 (37% of Dyn A2-10). Conclusions. The combination of enzyme inhibition experiments and noncompartmental kinetic analysis proved to be a powerful tool for the detailed evaluation of the metabolic fate of Dyn Al-13 in human blood and plasma.
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    URL: http://dx.doi.org/10.1023/A:1016211910107
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    Estimation of Impurity Profiles of Drugs and Related Materials. 12. Isolation and Identification of an Isomeric Impurity in Danazol (1995)
    Springer
    Pharmaceutical research 12 (1995), S. 295-298 
    Details
    ISSN: 1573-904X
    Keywords: danazol ; isodanazol ; impurity profiling ; identification ; isolation ; HPLC ; NMR spectroscopy ; HPLC-UV
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract We report on a new isomeric impurity of danazol. This impurity designated as isodanazol was detected by reversed-phase high-performance liquid chromatography (HPLC) and thin-layer chromatography (TLC). Its structure was determined after separation by preparative HPLC. Mass spectrometry revealed the isomeric nature of the impurity while the UV spectrum indicated profound difference in the isoxazole moieties. The structure of the isomeric isoxazole ring in isodanazol was determined by NMR spectroscopy using COSY, HETCOR and NOE measurements. The difference between the U V spectra of danazol and isodanazol is explained on the basis of the difference between the aromaticities of their isoxazole rings supported by quantum chemical calculations. The quantitative determination of the impurity down to the 0.05% level can be performed by HPLC, gas chromatography and TLC densitometry.
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    URL: http://dx.doi.org/10.1023/A:1016201630774
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    Analysis of transfer RNA during the early embryogenesis of the freshwater teleost,Heteropneustes fossilis (1995)
    Springer
    Molecular biology reports 21 (1995), S. 113-118 
    Details
    ISSN: 1573-4978
    Keywords: aminoacyl-tRNA synthetase ; embryogenesis ; HPLC ; total RNA ; transfer RNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Total RNA as well as transfer RNA were quantified from mature ova apart from four different embryonic stages namely mid-cleavage, early gastrula, mid-gastrula and organogenesis of the freshwater teleostHeteropneustes fossilis. Total RNA as well as transfer RNA quantity follow a similar variation pattern, being maximum during mid-gastrulation. When analysed by total amino acid acceptance capacity, transfer RNA shows its maximum activity during mid-gastrulation. This coincides with the higher ratio of tRNA to total RNA at this stage. The relative aminoacylation capacity for Ser, Gly, Asn and Thr are found to be higher (9–34%) compared to that for other amino acids. Total tRNA, resolved into three peaks upon HPLC fractionation, shows a high cumulative peak area during mid-gastrulation and organogenesis. These results indicate a switch over of maternal to embryonic translation machinery during gastrulation.
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    Sequestration of lichen compounds by lichen-feeding members of the Arctiidae (Lepidoptera) (1995)
    Springer
    Journal of chemical ecology 21 (1995), S. 2079-2089 
    Details
    ISSN: 1573-1561
    Keywords: Arctiidae ; Lepidoptera ; lichens ; lichen compounds ; HPLC ; sequestration ; chemical defense
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract A survey for the presence of sequestered lichen compounds in 103 wild-caught imagines representing eight different genera and 16 different species of the Arctiidae was conducted. Known lichen compounds were detected for the first time in 24 of the analyzed specimens (representing five different genera and 11 different species) based on their HPLC retention times and on their UV-absorption spectra. The anthraquinone parietin, the depside atranorin, as well as a hydrolytic cleavage product of the latter were among the lichen compounds most frequently detected in wild-caught imagines. The observed variation of sequestered lichen compounds in wild-caught imagines with unknown feeding history may be due to several reasons. Lack of lichen compounds in imagines may have been caused, for example, by larvae feeding on lichens with no or only minute amounts of phenolic products. The age of the specimens analyzed may also influence the results obtained. Avoidance of lichen compounds by selective feeding on those parts of lichen thalli that have no or little lichen products may be another reason for the lack of lichen compounds in imagines. Preliminary feeding experiments conducted with larvae ofEilema complana, for example, indicated that the larvae fed exclusively on the algal layer and cortex of the lichenCladonia pyxidata, whereas the medulla, which is rich in fumarprotocetrarie acid, was avoided. As expected, imagines hatching from the larvae were free of this lichen compound. Any ecological role of the sequestered lichen compounds for the herbivores is unknown. It is possible, however, that sequestered lichen compounds may be utilized for the chemical defense of arctiid moths or against microbial pathogens.
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    HPLC-analysis of algal pigments: comparison of columns, column properties and eluents (1995)
    Springer
    Journal of applied phycology 7 (1995), S. 487-494 
    Details
    ISSN: 1573-5176
    Keywords: HPLC ; method ; algal pigments ; chlorophyll ; carotenoid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of columns (Nucleosil C18ODS, MZ-PAH, YMC-PACK C30), column properties (inner diameters of 4 mm, 3 mm and 2 mm, pore-width 10 nm and 30 nm) and eluents (methanol, acetonitrile, acetone, water) were tested on the separation of algal pigments. The length of columns was 250 mm and particle size was 5 μm. Flow rates and gradients were adjusted to optimize peak separation; remaining chromatographic conditions were kept constant. The resolution of chromatographic systems was tested with pigment standards and various algal cultures. Total flow rate and retention times decreased with decreasing inner diameter, whereas pressure, sensitivity and peak-width increased. Pore width had negligible effects on the chromatographic separation of pigments under the test conditions. Only with acetonitrile as eluent were all the taxonomically important pigments resolved adequately: zeaxanthin (Cyanophyceae), lutein (Chlorophyceae), fucoxanthin (Bacillariopyceae), alloxanthin (Cryptophyceae), peridinin (Dinophyceae).
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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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    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).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00193484
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  • 91
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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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00194972
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  • 92
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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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00763105
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  • 93
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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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018946011652
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  • 94
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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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018916627891
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  • 95
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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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018977707960
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  • 96
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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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00877433
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  • 97
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    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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  • 98
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    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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  • 99
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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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00024025
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  • 100
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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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02184156
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