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  • Column liquid chromatography  (523)
  • Drosophila  (308)
  • Calcification
  • Rat
  • Springer  (1,131)
  • MDPI Publishing
  • 1990-1994  (755)
  • 1980-1984  (357)
  • 1965-1969  (19)
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  • 101
    Electronic Resource
    Electronic Resource
    Associations of esterase 6 allozyme and activity variation with reproductive fitness inDrosophila melanogaster (1994)
    Springer
    Genetica 94 (1994), S. 43-56 
    Details
    ISSN: 1573-6857
    Keywords: Drosophila ; esterase 6 ; reproduction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Previous studies have shown that the esterase 6 (EST6) enzyme ofD. melanogaster is mainly produced in the sperm ejaculatory duct of the adult male and comparisons of wild-type males with laboratory null mutants have suggested that the enzyme plays a role in reproductive fitness. In this study we have compared 18 field-derived lines each isoallelic forEst6 for differences in five components of male reproductive fitness. No consistent fitness differences were found among lines differing in respect of the two major allozyme classes EST6-F and EST6-S, despite other evidence that these two classes are not selectively equivalent in the field. However, differences in reproductive fitness were found among lines differing in the minor mobility variants that segregate within EST6-F and EST6-S. A failure to distinguish among these minor forms may explain the discrepancies in previous studies on the effects of the major EST6 allozymes on reproductive fitness. The most significant associations we have found between EST6 and reproductive fitness were due to variation in EST6 activity levels. Male EST6 activity levels were found to be positively correlated with their time to first mating, negatively correlated with the numbers of eggs laid and progeny produced by their mates, and negatively correlated with the frequency with which their mates remate. We conclude that some EST6 variants differ in components of male reproductive fitness operative in laboratory cultures. However, the evidence for fitness differences is stronger for variants affecting the amount, rather than the structure of the enzyme, and the direction of the differences varies between some of the fitness components tested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01429219
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  • 102
    Electronic Resource
    Electronic Resource
    Genetic, molecular and developmental analysis of the glutamine synthetase isozymes ofDrosophila melanogaster (1994)
    Springer
    Genetica 94 (1994), S. 275-281 
    Details
    ISSN: 1573-6857
    Keywords: Drosophila ; glutamine synthetase ; isozyme functional specialization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The glutamine synthetase isozymes ofDrosophila melanogaster offer an attractive model for the study of the molecular genetics and evolution of a small gene family encoding enzymatic isoforms that evolved to assume a variety of specific and sometimes essential biological functions. InDrosophila melanogaster two GS. isozymes have been described which exhibit different cellular localisation and are coded by a two-member gene family. The mitochondrial GS structural gene resides at the 21B region of the second chromosome, the structural gene for the cytosolic isoform at the 10B region of the X chromosome. cDNA clones corresponding to the two genes have been isolated and sequenced. Evolutionary analysis data are in accord with the hypothesis that the twoDrosophila glutamine synthetase genes are derived from a duplication event that occurred near the time of divergence between Insecta and Vertebrata. Both isoforms catalyse all reactions catalysed by other glutamine synthetases, but the different kinetic parameters and the different cellular compartmentalisation suggest strong functional specialisation. In fact, mutations of the mitochondrial GS gene produce embryo-lethal female sterility, defining a function of the gene product essential for the early stages of embryonic development. Preliminary results show strikingly distinct spatial and temporal patterns of expression of the two isoforms at later stages of development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01443441
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  • 103
    Electronic Resource
    Electronic Resource
    The role of extracellular calcium in pregnancy-induced attenuation of phenylephrine contraction in rat aorta with functional endothelium (1994)
    Springer
    Journal of comparative physiology 164 (1994), S. 81-87 
    Details
    ISSN: 1432-136X
    Keywords: Vascular smooth muscle ; Phenylephrine-induced contraction ; Pregnancy ; Aorta ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The effect of pregnancy on the supply of calcium ions for the contractile responses of rat aortic rings to phenylephrine was investigated. The contractility of intact aortic rings from pregnant rats, compared with that of similar rings from non-pregnant rats, to phenylephrine and potassium chloride was significantly decreased. Contractions of rings from non-pregnant rats, pretreated with phenylephrine or potassium chloride, in response to calcium chloride were greater than those of similarly treated rings from pregnant rats. When the concentration of calcium chloride in the medium bathing the rings was reduced to 0.8 mmol·l-1, the contractile response to phenylephrine was significantly (P〈0.005) inhibited in rings from both pregnant and non-pregnant rats but to a greater extent in rings from non-pregnant rats. Contractions of aortic rings from pregnant rats in response to phenylephrine in calcium-free medium were similar to those of rings from non-pregnant rats, suggesting equal dependence on calcium from intracellular stores. The results suggest that pregnancy decreased the response to calcium influx into the aortic smooth muscle cells through both receptor-and voltage-operated calcium entry pathways. Since de-endothelialisation reversed the pregnancy-induced diminished contraction to phenylephrine, it is likely that pregnancy interferred with contractions induced by activation of receptors with phenylephrine through enhanced production of endothelium-derived relaxing factor(s).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00714575
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  • 104
    Electronic Resource
    Electronic Resource
    Determination of sugars by liquid chromatography with post-column catalytic derivatization and fluorescence detection (1994)
    Springer
    Chromatographia 38 (1994), S. 12-16 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Carbohydrates ; Post-column fluorescence derivatization ; Post column catalytic reaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method for the determination of reducing sugars such as fructose and glucose and nonreducing sugar such as sucrose by high performance liquid chromatography followed by an acidic hydrolysis and a derivatization with benzamidine has been developed. After separation of sugars on a gel column packed with a polymer-based cation exchange material (Sugar-Pak I, Waters-Millipore), the sucrose is first hydrolysed in a solid phase reactor to convert it into reducing subunits. A post-column fluorigenic reaction with benzamidine under alkaline condition allows the selective determination of both natural and converted reducing carbohydrates. This procedure has proven to be selective (fluorigenic detection) and highly sensitive (allowing detection as little as picomoles amounts), reproducible and linear over a broad range of concentrations: 5×10−4 to 1.0×10−2 M. The applicability of this method to natural matrices such as plant extracts and beverages is also described. The sugar content of a barley extract has been determined and compared with a specific enzymatic test. The determined sugar content of natural and commercial lemon juices as well as of Cola beverages has been compared with those found by the conventional LC refractive index analytical procedure. In all cases, the results were comparable and were within the experimental errors of the methods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02275720
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  • 105
    Electronic Resource
    Electronic Resource
    Chromatography of esculin from stems and bark ofAesculus hippocastanum L. for consecutive vegetative periods (1994)
    Springer
    Chromatographia 38 (1994), S. 766-770 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Thin-layer chromatography ; Densitometry ; Spectrophotometry of extracts ; Esculin, fraxin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Coumarin glucosides, esculin and fraxin, were determined in several older and younger layers of stems ofAesculus hippocastanum L. by three methods (TLC-densitometry, TLC-extraction and spectrophotometric determinations, HPLC) during the vegetative period (May–October). Variation of their content during these months is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02269634
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  • 106
    Electronic Resource
    Electronic Resource
    Rapid method for determination of phenylurea herbicides in milk (1994)
    Springer
    Chromatographia 38 (1994), S. 88-92 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Phenylurea herbicides ; Milk
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method has been developed for the determination of thirteen phenylurea herbicide residues in milk. It involves one-step solvent extraction of the milk with methanol by ultrasonication. The extract is cleaned up on an Amberchrom resin cartridge. Reversed-phase, gradient elution, high-performance liquid chromatography with UV detection at 242 nm is used to analyse the residues. The recovery of thirteen phenylurea pesticides is quantitative, ranging from 71.4% to 97.9% for the individual herbicides investigated at concentrations around 0.05 mg kg−1 and from 65.1% to 95.6% around 0.005 mg kg−1. The method is not associated with any of the emulsion problems common to conventional solvent extraction, which considerably reduce the sample clean-up process compared with existing methods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02275732
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  • 107
    Electronic Resource
    Electronic Resource
    Lipid class analysis by normal phase high performance liquid chromatography, development and optimization using multivariate methods (1994)
    Springer
    Chromatographia 38 (1994), S. 317-324 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Lipid class analysis ; Experimental design and optimization ; Chemometrics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A general method for the analysis of lipid classes by liquid chromatography has been developed using a multivariate optimization strategy to target optimal system conditions. The method was validated using a ruggedness test in the form of a Plackett-Burman design thereby exploring the immediate region around the optimum to ensure stable analytical conditions. Detection and quantitation were optimized by a factorial design in the light scattering detector parameters thus ensuring maximum detector response. This method was found to be suitable for a broad range of lipid sources from vegetable and animal origin, examples of the separation achieved are given for oat kernel, soybean and bovine milk lipids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02269774
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  • 108
    Electronic Resource
    Electronic Resource
    Determination of catecholamines as aminochromes by micellar liquid chromatography with thermal lens spectrophotometric detection (1994)
    Springer
    Chromatographia 38 (1994), S. 365-372 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Micellar liquid chromatography ; Determination of catecholamines ; Aminochromes ; Thermal lens spectrometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The determination of catecholamines (CAs) using micellar liquid chromatography with thermal lens spectrophotometric detection has been studied. CAs are oxidized with hexacyanoferrate(III) to aminochromes which are separated with a mobile phase of 0.05 M sodium dodecyl sulphate, 7% propanol and 0.03 M citrate buffer, pH 4.8, on a partially endcapped C18 column. The aminochrome-micelles and aminochrome-stationary phase association constants are evaluated. Using the 488 nm line of an Ar+ laser with 250 mW pump power the limits of detection are about 4 ng mL−1. The technique is applied to the determination of unconjugated CAs in urine using isoproterenol as internal standard.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02269782
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  • 109
    Electronic Resource
    Electronic Resource
    Control of adsorption and solubility in gradient high-performance liquid chromatography. Part 2: Sudden-transition gradient elution of styrene/ethyl methacrylate copolymers (1994)
    Springer
    Chromatographia 38 (1994), S. 559-565 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Copoly(styrene/ethyl methacrylate) ; Gradient elution, sudden transition ; Precipitation chromatography of polymers ; Solubility of polymers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Copolymers from styrene and ethyl methacrylate have been separated according to composition by methanol gradients on a cyanopropyl column after injection inton-heptane and a subsequent rapid increase of dichloromethane (DCM) concentration from zero to a constant value in the range from 10 to 40%. Retention and resolution in sudden-transition gradients increased with decreasing DCM concentration. The gradient rate was varied between 2.5 and 7.5%/min with optimum resolution at 2.5% min. At a level of 20% DCM and a gradient rate of 5%/min, the separation of a mixture of five copolymers in a sudden-transition gradient was the same as with the corresponding common gradient, i.e., with injection into a mixture ofn-heptane and 20% DCM. Elution was also achieved at a level of 20% DCM by continuous addition of tetrahydrofuran (THF) instead of methanol. With THF, the peaks appeared later than with methanol in spite of the fact that methanol is a non-solvent and THF a good solvent for the polymers investigated. This indicates that elution was, in the first instance, caused by the polarity of the eluent. The elution characteristics of the copolymers in the system heptane/methanol at constant DCM concentration were basically similar to the already known characteristics iniso-octane/methanol at constant THF concentrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02277154
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  • 110
    Electronic Resource
    Electronic Resource
    Ligand-exchange chromatography of amino acid enantiomers and its application to the biotransformation of DL-aspartic acid byPseudomonas dacunhae (1994)
    Springer
    Chromatographia 39 (1994), S. 15-22 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ligand exchange ; Amino acid enantiomers ; DL-aspartic acid ; Pseudomonas dacunhae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation of the D and L enantiomers of eighteen essential α amino acids has been investigated by ligand-exchange chromatography (LEC). The effect of column temperature on the retention times and resolution of individual amino acid enantiomers has been studied by varying the temperature from 25 to 50 °C for a mobile phase containing Cu2+ ions. By use of a temperature of 50 °C and Zn2+ in the mobile phase, eight of the eighteen amino acid enantiomers can be resolved sufficiently well for practical application. Only phenylalamine, tyrosine, and tryptophan can be separated by use of Ni2+ as complexation metal at 50 °C. LEC has been used to monitor the decarboxylation of racemic DL-aspartic acid byPseudomonas dacunhae. Analysis of DL amino acid enantiomers in different media was performed at column temperatures of 30 and 50°C by addition of 0.125 mM Cu2+ to the aqueous mobile phase. It was found that the analytical performance is most dependent on the identity of the metal used for complexation; the concentration of the metal was of secondary importance and the column temperature less important still.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02320452
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  • 111
    Electronic Resource
    Electronic Resource
    Retention and selectivity of aromatic hydrocarbons with mono-substituted polar groups in ternary RP-HPLC systems (1994)
    Springer
    Chromatographia 39 (1994), S. 67-70 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed phase systems ; Ternary eluents ; Mono-substituted aromatics ; Retention and selectivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The variation in selectivity for aromatic hydrocarbons with mono-substituted polar groups is investigated in ternary mobile-phase systems on C18 stationary phases. The dependence of log k′ on the proportions of two modifiers was determined for the solutes within the concentration range of ternary systems obtained by mixing two binary eluents: methanol + water and tetrahydrofuran + water or acetonitrile + water and tetrahydrofuran + water. The nature of the relationships is explained in terms of molecular shape, molecular interactions between solute and extracted modifier and the ordering of solvated ligands on the stationary phase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02320460
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  • 112
    Electronic Resource
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    The simultaneous determination of L-697, 661, a HIV-1 specific reverse transcriptase inhibitor, and its 6-hydroxy metabolite in human plasma via column-switching high performance liquid chromatography (1994)
    Springer
    Chromatographia 39 (1994), S. 79-84 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Column switching ; HIV type 1 reverse transcriptase inhibitor ; Acquired immune deficiency syndrome ; L-697, 661
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method for the determination of L-697, 661, a human immunodeficiency virus type 1 reverse transcriptase inhibitor, and its 6-hydroxy metabolite in plasma is described. Following analyte isolation via solid phase extraction, samples are analyzed by HPLC using a column switching system. Column switching allows each analyte to be simultaneously analyzed under isocratic reverse phase conditions in a run time of 21 minutes. The assay was linear in the concentration range of 10–500 ng/mL for each analyte when 1 mL aliquots of plasma were extracted. The assay has been fully validated and utilized for human pharmacokinetic studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02320463
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  • 113
    Electronic Resource
    Electronic Resource
    Reversed phase behaviour of high molecular mass polystyrenes in ethyl acetate solvent mixtures (1994)
    Springer
    Chromatographia 39 (1994), S. 663-667 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Polystyrene ; Ethyl acetate ; Dichloromethane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The reversed phase behaviour of high molecular mass polystyrenes was investigated on C18 bonded phase columns with ethyl acetate-methanol and ethyl acetateacetonitrile mobile phases. The results are compared with the corresponding dichloromethane mobile phases. The ethyl acetate-methanol mobile phase showed anomalous elution behaviour, similar to other previously investigated solvent combinations with methanol. The ethyl acetate-acetonitrile mobile phase showed no anomalous behaviour, increased retention and, elution over a wider composition range compared with the dichloromethane-acetonitrile system. However, resolution between adjacent molecular masses was considerably worse.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02274580
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  • 114
    Electronic Resource
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    Simultaneous quantitative measurement of a new platelet activating factor antagonist (BN 50730) and its two main metabolites in human plasma and urine by LC-MS (1994)
    Springer
    Chromatographia 39 (1994), S. 228-238 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; LC/MS coupling ; Particle Beam interface ; Plasma and urine samples ; BN50730 and its metabolites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple and sensitive assay has been developed for the quantitative measurement of a new platelet activating factor antagonist (BN50730), and its two main metabolites (BN50727 and BN50922), at the picomole level in human plasma and urine. The three compounds of interest and the internal standard (BN50765) were measured by combined LC-negative chemical ionization MS. A simple solid-liquid extraction procedure was used to isolate the parent drug and the two metabolites. The MS was tuned to monitor the intense ionm/z 333 generated in the ion source by a dissociative capture process. The assay was on 1 ml plasma or 0.1 ml urine and the quantitation limit was calculated as 1 ng·ml−1. The very low relative standard deviations and mean percentages of error calculated for within-day or between-day repeatability assays demonstrate the ruggedness of the technique for routine determination in biological fluids. Some preliminary results on the pharmacokinetics of the parent drug and its two main metabolites illustrate the applicability of this method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02274505
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  • 115
    Electronic Resource
    Electronic Resource
    Generation of split-flow micro-gradients for capillary HPLC (1994)
    Springer
    Chromatographia 39 (1994), S. 279-284 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Capillary columns for LC ; Micro-gradient generation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The generation of a micro-gradient for micro HPLC capillary columns is described. The system used is a modified and improved version of a split flow gradient elution device. Gradient tests have been performed and have shown good reproducibility under all conditions. The system has been successfully coupled with a particle beam LC-MS interface and the analysis of a mixture of twenty seven basic or neutral pesticides is reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02274514
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  • 116
    Electronic Resource
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    Salt effects in anion exchange displacement chromatography: Comparison of pentosan polysulfate and dextran sulfate displacers (1994)
    Springer
    Chromatographia 39 (1994), S. 409-418 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion-exchange chromatography ; Protein purification ; Pentosan polysulfate displacers ; Dextran sulfate displacers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Experimental studies were carried out to investigate the utility of pentosan polysulfate as a low molecular weight polyelectrolyte displacer for the purification of proteins in anion-exchange displacement systems. In addition, the influence of mobile phase salt concentration on displacer efficacy, protein-protein resolution, and displacement development were studied for several anionic displacers. It was found that while large polyelectrolytes (50 kd dextran sulfate) were efficient displacers for a wide range of salt concentrations, relatively small polyelectrolytes (3 kd pentosan polysulfate) were seen to act as an efficient displacer only under conditions of high salt micro-environments. In addition, for proteins exhibiting similar affinities, zone mixing at the protein-protein boundary was found to be quite sensitive to the salt concentration. Finally, displacement chromatography was successfully implemented for the separation of proteins from milk whey.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02278755
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  • 117
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    Separation of chlamydosporol epimers by reversed-phase HPLC using commercial solvent optimisation software (1994)
    Springer
    Chromatographia 39 (1994), S. 443-447 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Mycotoxins ; Chlamydosporol epimers ; Solvent optimisation ; Fusarium species
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Two epimers of the mycotoxin chlamydosporol were separated by HPLC on an RP-18 column using a quaternary mobile phase consisting of water (79.1%), methanol (10.0%), acetonitrile (10.4%) and tetrahydrofuran (0.5%), with a flow rate of 1 ml min−1. This optimal composition of mobile phase, with which the resolution value for the two epimers (1 and2) was 2.73 with retention times of 5.88 and 7.12 min, respectively, was achieved by the application of Philips Solvent Optimisation Software PU 6100. The presence of free silanols on the stationary phase was shown to be an essential requirement for the separation of the chlamydosporol epimers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02278760
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  • 118
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    Determination of tacrolimus (FK 506) in whole blood using liquid chromatography and fluorescence detection (1994)
    Springer
    Chromatographia 39 (1994), S. 490-496 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Precolumn derivatization ; Dansylhydrazine ; Fluorescence detection ; Tacrolimus (FK 506) in blood
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A sensitive and selective liquid chromatographic method, using precolumn derivatization with dansylhydrazine followed by fluorescence detection, has been developed for the determination of tacrolimus (FK 506) in whole blood. After haemolysis, whole blood samples are extracted with diethyl ether and derivatized. After on-line removal of excess dansylhydrazine on a C18 precolumn, the derivative is loaded on to a C18 clean-up column, and a heart cut is subsequently transferred to a graphitized carbon column, where the final separation takes place. The method requires 1 ml of sample and has a limit of quantitation of 3 ng/ml. At the 15 ng/ml level the precision isca 10%, and the response is linear from the limit of quantitation toca 200 ng/ml of FK 506 in whole blood. The capacity of the method is 50 samples/day and about 1000 1-ml samples can be analyzed without changing either clean-up or separation column. Finally, the applicability of the method for therapeutic drug monitoring is shown.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02278767
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  • 119
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    Spectroscopic studies of butylphenyl, mono-ol and perfluorinated bonded phases (1994)
    Springer
    Chromatographia 39 (1994), S. 520-528 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; New bonded phases ; 13C and29Si CP-MAS NMR ; DRIFT ; ESCA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A variety of olefins were bonded to silaceous supports through a hydride modified substrate. The products were then examined by13C and29Si solid state-NMR with cross-polarization (CP) and magic angle spinning (MAS). Information about the surface was also obtained by diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) and the related photoelectron spectroscopic technique (ESCA). Carbon analysis on bonded silicas was carried out and surface coverage was calculated. Confirmation of the organic groups bound to the silica support was possible. The hydride intermediate is shown to be a versatile material for bonding a wide variety of organic moieties to silica surfaces.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02268274
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  • 120
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    Analysis of isomers of cholesteryl acetate hydroperoxides by HPLC and GC-ITDMS (1994)
    Springer
    Chromatographia 39 (1994), S. 577-580 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography-mass spectrometry ; Column liquid chromatography ; Cholesteryl acetate ; Hydroperoxide formation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Gas chromatographic, high performance liquid chromatographic and GC-ion trap detector mass spectrometric analyses of the hydroperoxides formed during thermal peroxidation of cholesteryl acetate, are reported and discussed. The hydroperoxides were separated from the thermal-oxidised mixture by solid-phase extraction, fractionated and individually collected by HPLC. Each hydroperoxide was then chemically reduced with NaBH4 to a hydroxy-derivative. The GC and MS characteristics of hydroxy- and TMS-derivatives were compared against available standards. Only 7β-hydroperoxide and 7α-hydro-peroxide of cholesteryl acetate were found, as reported in the literature for cholesterol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02268282
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  • 121
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    Retention behavior of aromatic hydrocarbons in reversed-phase liquid chromatography with ion-exchange-induced stationary phases (1994)
    Springer
    Chromatographia 39 (1994), S. 597-601 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion-exchange-induced stationary phase ; Retention behavior ; Aromatic hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention behavior of aromatic hydrocarbons on anion-exchangers modified with alkylsulfate or alkanesulfonate has been examined by column liquid chromatography. Several parameters affected the retention of analytes, involving concentration of the modifier in the mobile phase, its alkyl chain length and mobile phase composition. Stationary phases modified with a reagent having longer alkyl chains achieved better column efficiency. The separation factor achieved on ion-exchange-induced stationary phases foro-terphenyl and triphenylene was larger than that on alkyl-bonded silica gel.
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    URL: http://dx.doi.org/10.1007/BF02268286
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  • 122
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    Application of liquid chromatography-particle beam mass spectrometry and gas chromatography-mass spectrometry for the identification of metabolites of polycyclic aromatic hydrocarbons (1994)
    Springer
    Chromatographia 38 (1994), S. 781-788 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Gas chromatography ; Particle beam MS detection ; Polycyclic aromatic metabolites ; Biodegradation in water
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Two liquid chromatography-particle beam mass spectrometry (LC-PBMS) systems have been used for analysis of polycyclic aromatic hydrocarbon metabolites in water samples from a biological decomposition model experiment. The results were compared with those obtained by classical gas chromatography-mass spectrometry. Evaluation of spectral data indicated the presence of six main metabolites; 1H,3H-naphtho [1,8-cd]pyran-1,3-dione, 1-(hydroxymethyl)naphthalene, and 1,2-acenaphthenedione were identified by use of standard substances and spiking experiments. Enrichment of the investigated water samples with online pre-column (C18) concentration, freeze-drying, and solvent extraction led to similar results with only slight differences. The application of microbore separation columns proved to be a promising tool in particle beam LC-MS measurements.
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    URL: http://dx.doi.org/10.1007/BF02269637
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    Efficiency of porous hydrophilic polymer-based packing materials in chromatographic analysis of drugs existing with polypeptide (1994)
    Springer
    Chromatographia 38 (1994), S. 177-182 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Hydrophilic polymer-based packing material ; Direct injection of serum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A size monodispersed restricted-access polymeric packing material has been prepared through a simple and easy one-step method of co-polymerization of glycerol monomethacrylate and glycerol dimethacrylate with cyclohexanol as prorogen. A typical seeded polymerization (two step swelling and polymerization method) in an aqueous medium gave a 90 % yield of porous beads which could be utilized as a packing material in high performance liquid chromatography (HPLC) without any size classification due to the excellent size monodispersity. A BET measurement and size exclusion chromatography in either tetrahydrofuran or water revealed that the prepared material had only small pores (around 100 Å in diameter). It showed ample hydrophobicity for the separation of hydrophilic drug molecules in 10% aqueous acetonitrile buffer, while polypeptides such as bovine serum albumin were excluded and eluted before the void volume of the column with quantitative recovery.
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    URL: http://dx.doi.org/10.1007/BF02290333
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    Selective and sensitive analysis of 1-nitropyrene in diesel exhaust particulate extract by multidimensional HPLC (1994)
    Springer
    Chromatographia 38 (1994), S. 199-206 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Nitro-PAHs ; Diesel particulate extract ; Column switching
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A multicolumn (MC) HPLC method for the determination of 1-nitropyrene (1-NP) at trace-levels via on-line reduction to 1-aminopyrene and fluorescence detection is presented. On the first column, packed with a pyrenebutyric acid amide stationary phase, the nitro-derivatives of PAHs are strongly retained and separated from other matrix components. The nitro-PAHs-containing fractions are transferred onto a RP18-column via stepwise gradient elution and finally separated according to their various lipophilicities and sizes. To increase the overall selectivity and sensitivity of the multidimensional method (MD-HPLC system) post-column, on-line reduction of the nitro-PAHs to the respective amino-PAHs via a short catalysis column is performed thus enhancing the sensitivity significantly (to low pg levels). The applicability of this method for the determination of trace amounts of 1-NP in real samples (diesel particulate extracts) is demonstrated.
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    URL: http://dx.doi.org/10.1007/BF02290337
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    Molecular shape recognition capability of liquid-crystal bonded phases in reversed-phase high performance liquid chromatography (1994)
    Springer
    Chromatographia 38 (1994), S. 295-303 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Liquid crystal phases ; Molecular shape recognition ; Polycyclic aromatic hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The chromatographic retention behaviour of two liquidcrystal bonded phases have been evaluated using polycyclic aromatic hydrocarbons (PAHs) as the probe samples in reversed-phase high performance liquid chromatography (RP-HPLC). The results clearly indicate that these phases have better planarity and shape recognition capabilities than commercially-avaialble polymeric octadecylsilica (ODS) phases whose strong planarity and shape selectivities were found earlier. It can also be concluded from the chromatographic observations that the shape recognition capability of these phases is dependent on both mobile phase composition and column temperature, but that the effect of mobile phase and temperature on the shape selectivity work independently. The retention behaviour can be explained by changes in the phase structure with changes of eluent composition and temperature.
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    URL: http://dx.doi.org/10.1007/BF02269771
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    In-line derivatization method for fluorometric determination of catecholamines by high performance liquid chromatography (1994)
    Springer
    Chromatographia 38 (1994), S. 591-594 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; In-line derivatization ; Fluorometric determination ; Catecholamines in urine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A fluorometric method has been developed for the determination of norepinephrine, epinephrine and dopamine by high-performance liquid chromatography. Catecholamines extracted from urine were separated by reversed-phase chromatography with an alkaline mobile phase (pH 8.0, 20 mM sodium tetraborate containing 30 mM 1-butaneboronic acid) and were fluorometrically detected (Ex 400 nm and EM 475 nm) via in-line derivatization at high temperature (100 °C). Retention times for norepinephrine, epinephrine, dopamine and isoproterenol as an internal standard were 8, 10, 13 and 28 min, respectively. Calibration curves for these compounds were linear from 4 to 100 ng/ml standard solution. The detection limit (signalto noise ratio=3) for norepinephrine, epinephrine and dopamine was 0.1, 0.2 and 0.8 ng. The assay of catecholamines in human urine is also described.
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    URL: http://dx.doi.org/10.1007/BF02277159
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    Determination of glutathione in pharmaceuticals and cosmetics by HPLC with UV and fluorescence detection (1994)
    Springer
    Chromatographia 39 (1994), S. 23-28 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Glutathione ; Pharmaceuticals and cosmetics ; Pre-chromatographic derivatization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A selective HPLC determination of reduced glutathione (GSH) in pharmaceutical and cosmetic formulations is described based on prechromatographic derivatization with 4-(6-methylnaphthalen-2-yl)-4-oxo-2-buteneoic acid. The derivatization reaction is rapid under mild reaction conditions (10 min at ambient temperature and pH 7.5) and the excess reagent can be removed by liquid-liquid extraction. The thiol adducts were chromatographed on a C-8 column using 0.05 M triethylammonium phosphate (pH 4.0) — acetonitrile 68∶32 (v/v), as the mobile phase; UV and fluorescence detection (lem 450 nm, lexc 300 nm) were both used. The structure of the thiol adducts was confirmed by1H and13C NMR spectra using sodium methanethiolate as thiol nucleophile.
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    URL: http://dx.doi.org/10.1007/BF02320453
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    Retention parameters of aromatic hydrocarbons with mono-substituted polar groups in binary RP-HPLC systems (1994)
    Springer
    Chromatographia 39 (1994), S. 51-61 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed-phase systems ; Binary eluents ; Mono-substituted aromatics ; Retention and selectivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Capacity factor (k′) values of aromatic hydrocarbons with mono-substituted polar-groups are correlated for reversed-phase systems involving stationary phases with C18 or C4 ligands chemically bonded to silica and a binary aqueous eluent containing modifiers: methanol, acetonitrile, tetrahydrofuran, isopropanol, dioxane or dimethoxyethane. The relative retention variations of the solutes are interpreted with special consideration of their interactions with non-polar stationary phases and the molecular structure of the modifiers and solutes. Rules for retention and selectivity optimisation in RP-HPLC systems are given.
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    URL: http://dx.doi.org/10.1007/BF02320458
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    System peaks in single column ion chromatography (SCIC) with indirect spectrophotometric detection (1994)
    Springer
    Chromatographia 39 (1994), S. 713-718 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion chromatography ; System peaks ; Indirect detection ; Anions and cations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The most popular eluents for SCIC are organic acids and their salts with one or more kinds of ion taking part in the elution process. These ions compete for ion-exchange equilibria. After an injection, the equilibria are disturbed and a re-equilibration process occurs resulting in extraneous peaks (system peak). A mechanism based on these aspects is proposed which is used successfully in the interpretation of the effects of sample properties and eluent parameters on system peaks. Experiments in the analysis of both cations and anions have been carried out to support this mechanism with eluents comprising two kinds of eluent ions. An equation for capacity factors in such systems is also derived.
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    URL: http://dx.doi.org/10.1007/BF02274588
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    Kinetic performance of open-tubular and packed columns in LC using the same stationary phase: Immobilized polymethyloctadecylsiloxane (1994)
    Springer
    Chromatographia 39 (1994), S. 729-739 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Polymeric stationary phase coatings ; PMSC18 ; Column evaluation ; Peak capacity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary For the first time a direct comparison of the kinetic performance of narrow-bore (5–15 μm I.D.) opentubular columns (OTCs) and conventional packed columns in LC was carried out with stationary and mobile phases with identical chemical composition. The polymeric stationary phase was a polymethyloctadecylsiloxane (PMSC18) and the columns were evaluated in reversed-phase LC. In the open-tubular columns oncolumn detection was performed with laser-induced fluorescence. The observed column performance is presented in various ways, to take account of the basic differences of OTCs and packed columns. Experimental data was compared with theoretical models by use of a curve fitting procedure. The static coating method generates OTCs that perform close to theoretical predictions, and the packed columns were outperformed by the OTCs with regard to efficiency. A 6 m long and 6.3 μm I.D. OTC showed a minimum reduced plate height, hmin. of 0.5 at k′=0.27, which equals 1 900 000 theoretical plates. Also, it was established that the open-tubular columns provide higher resolution in a given analysis time. However, the importance of sufficient retention in OTCs is once again substantiated. Peak capacity plots illustrate that the k′ “window” should be optimized in order to reach maximum resolution (k′ 0–2 for OTCs and 0–5 for packed columns).
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    URL: http://dx.doi.org/10.1007/BF02274590
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    Chromatographic characterization of a hexapeptide containing three thiol groups, intrinsic to the metallothionein structure (1994)
    Springer
    Chromatographia 39 (1994), S. 146-154 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Peptide characterization ; Thiol groups ; Electrochemical detection ; Metallothionein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The hexapeptide Lys-Cys-Thr-Cys-Cys-Ala [56–61] MT I is a molecule intrinsic to the metallothionein structure. Its chromatographic behaviour on a reversed-phase column, using electrochemical detection has been studied in order to get a better understanding of its chemical stability under various conditions. The chromatogram of the peptide consists of two peaks. The optimization procedure for their separation is presented and a hydrodynamic voltammogram has been generated. The relative proportion of the two peaks can vary with experimental conditions and is clearly dependent of the peptide concentration. Following the various experiments to which the peptide was submitted, namely elution after air oxidation, under inert atmosphere, in basic pH, after addition of an oxidizing agent (H2O2) and after addition of a reducing agent (2-mercaptoethanol), a reaction scheme was suggested: transformations of the reduced hexapeptide (three free thiol groups) into—as a first step—its intramolecular oxidized form (one SS bond, one free SH) and then into—as a second step—the fully oxidized dimeric form (no more free SH). Electrochemical detection allows a quantitative follow-up of the thiol oxidation and hence, of the disappearance of the reduced peptide.
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    URL: http://dx.doi.org/10.1007/BF02274493
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    Luminarin 9: A new fluorescent reagent for the precolumn derivatizatioin of main volatile and non-volatile N-nitrosamines in RP-HPLC (1994)
    Springer
    Chromatographia 39 (1994), S. 185-191 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; N-nitrosamines ; Fluorescent derivatives ; Luminarin 9 ; Precolumn derivatization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A sensitive precolumn fluorescence derivatization method for low level detection of the, volatile (N-nitrosodimethylamine and N-nitrosopyrrolidine) and non-volatile N-nitrosamines (N-nitrosoproline and N-nitrosodiethanolamine) an high-performance liquid chromatography was developed. This method is based on the denitrosation of the compounds of interest by a mixture of hydrobromic acid and acetic acid to produce the corresponding secondary amines. These are, then, able to react with, a quinolizinocoumarin derivative (luminarin 9®) to form highly fluorescent labelled N-nitrosamine derivatives. The structural elucidation of the luminarin 9® derivatives of N-nitrosoproline and N-nitrosodimethylamine by way of example, were established by liquid chromatography-mass spectrometry (LC-MS) and by direct chemical ionization-mass spectrometry (CI-MS). The separation, derivatization and detection conditioins were optimized for all the studied compounds. The detection limits (signal to noise ratio=3) were between 0.4 and 1.0 pmol injected depending on the compound. The calibration graphs were linear for derivatized amounts in the range of 0.5–40 nmol for N-nitrosodimethylamine and N-nitrosopyrrolidine, 0.4–2- nmol for N-nitrosoproline and 1.0–40 nmol for N-nitrosodiethanolamine. The repeatability (RSD less than 3.5%, n=6) and reproducibility (RSD less than 4.8%, n-6) were satisfactory.
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    URL: http://dx.doi.org/10.1007/BF02274499
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    Computerized optimization of gradient elution conditions with ternary solvent mobile phases in RPLC (1994)
    Springer
    Chromatographia 39 (1994), S. 216-223 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Gradient elution ; Optimization of gradients ; Ternary solvent mobile phase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In this work, an optimization procedure for gradient RPLC separation, using ternary mobile phases, is described. This procedure requires eight preliminary experiments in gradient elution mode to predict the retention surface for each solute over the whole triangular space. This is followed by computerized calculations to determine the best ternary gradient elution profile with respect to both selectivity and analysis time. The efficiency of this procedure from the point of view of rapidity and of accuracy, is illustrated for the specific separation of twelve phenyl urea herbicides.
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    URL: http://dx.doi.org/10.1007/BF02274503
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    Theoretical models for electrodialytic sample treatment in trace analysis by liquid chromatography (1994)
    Springer
    Chromatographia 39 (1994), S. 460-468 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Electrodialytic sample treatment ; Computer models ; Analyte enrichment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Basic considerations for analyte enrichment and recovery obtainable by electrodialysis as a sample treatment method are given. Equations are derived which describe the dependence of the concentration profiles of ionic compounds on the electric field strength in a set-up with stagnant donor and acceptor solutions. It is shown that analyte recovery increases when less ion-selective membranes are used in the electrodialysis cell. Computer models are used to estimate the analyte enrichment for a flowing donor (sample) and a stagnant acceptor phase. About 10-fold enrichment can be obtained in an electrodialytic sample treatment system within 20 min under maximum current conditions. A compromise has to be found between analyte recovery and the donor (sample) flow rate.
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    URL: http://dx.doi.org/10.1007/BF02278763
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    Control of adsorption and solubility in gradient high-performance liquid chromatography (1994)
    Springer
    Chromatographia 39 (1994), S. 557-563 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Copoly(styrene/methyl methacrylate) ; Gradient elution ; Precipitation chromatography of polymers ; Solubility of polymers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Copolymers from styrene and methyl methacrylate (MMA) were separated by both normal and reversedphase gradient chromatography. Both modes could be performed by sudden-transition gradients where the polymers were injected into a non-solvent whose polarity was either rather low (e.g.,n-heptane) or high (e.g., acetonitrile). Then the solvent strength of the starting eluent was rapidly increased to a given level by addition of dichloromethane. Under properly defined conditions, the sample components still remained on the column. Elution could be triggered off by the steady addition of another non-solvent whose polarity was opposite of that of the starting non-solvent. Thus, the mixture of five copolymers with MMA content ranging from 14 to 84% could be separated on a polar cyanopropyl column by injection inton-heptane and elution through acetonitrile (normal phase mode) and on a RP C18 column by injection into acetonitrile and elution throughn-heptane (reversed-phase mode), provided that in both modes about 30% dichloromethane was added to the starting non-solvent. The elution sequence in the reversed-phase mode was opposite to that in the normal-phase mode, obeying the approved polarity rules of chromatography in both cases.
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    URL: http://dx.doi.org/10.1007/BF02268279
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    Rapid separation of polycyclic aromatic hydrocarbons by packed column supercritical fluid chromatography (1994)
    Springer
    Chromatographia 39 (1994), S. 607-611 
    Details
    ISSN: 1612-1112
    Keywords: Supercritical fluid chromatography ; Column liquid chromatography ; Polycyclic aromatic hydrocarbons ; Environmental samples
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation in 6 minutes of the sixteen US Environmental Protection Agency (EPA) polycyclic aromatic hydrocarbons (PAHs) on a single packed column by supercritical fluid chromatography (SFC) is described and compared to that obtained using liquid chromatography with the same column. Several environmental samples containing polycyclic aromatic hydrocarbons obtained from various sources including soil, water, petrochemicals and coal have been analysed by SFC under optimised conditions. Packed column SFC is shown to be an efficient and promising method for the rapid monitoring of environmental polycyclic aromatic hydrocarbons.
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    URL: http://dx.doi.org/10.1007/BF02268288
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    Capillary electrophoresis as an alternative to HPLC for determination of honey flavonoids (1994)
    Springer
    Chromatographia 38 (1994), S. 71-78 
    Details
    ISSN: 1612-1112
    Keywords: Micellar electrokinetic capillary chromatography ; Column liquid chromatography ; Honey flavonoids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The general objective is to provide an alternative methodology based on capillary electrophoresis (CE) to characterize flavonoids from honey and hence determine its botanical origin. The specific objective is to compare the separation of flavonoids by CE with those achieved by HPLC to assess CE as an alternative technique for the determination of honey flavonoids. Fourteen different flavonoids isolated from honey were analysed by MECC and compared to the HPLC separations. It was difficult to find specific experimental conditions to separate all the flavonoids from honey in a single MEKC run. Three chromatographic conditions are optimized and, depending on the flavonoid markers sought in honey, the appropriate detection method should be chosen. Compared to the HPLC results, it is clear that CE could be an alternative technique in honey flavonoids analysis and particularly in the study of its geographical and floral origin.
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    URL: http://dx.doi.org/10.1007/BF02275729
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    Enantiomeric resolution of anti-HIV agents on a cellulose derivative chiral stationary phase (1994)
    Springer
    Chromatographia 38 (1994), S. 57-61 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Enantio separation ; ChiralcelR OJ ; Anti-HIV agents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Anti-HIV enantiomeric 1H, 3H-thiazolo[3, 4-a] benzimidazoles have been stereospecifically analyzed by elution on a column of cellulose tris-(4-methyl-phenylbenzoate)ester adsorbed on macroporous silica (ChiralcelR OJ). The enantiomeric resolution of the compounds examined is linked to a complex and competitive contribution of different factors.
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    URL: http://dx.doi.org/10.1007/BF02275727
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    Statistical scanning method for the optimization of gradient elution high performance liquid chromatography (1994)
    Springer
    Chromatographia 38 (1994), S. 187-190 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Optimal mobile phase ; Gradient elution ; Microcomputer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A computer-assisted method is presented for the optimization of separation in gradient elution reversed-phase HPLC. The method is based on a polynomial estimation from nine preliminary experiments according to a two-factor (initial solvent composition C and gradient time T) rectangular design. This is followed by a two-dimension computer scanning technique. Resolution is used as the selection criterion. Good agreement was obtained between predicted data and experimental results.
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    Salt promoted adsorption chromatography of malted barley amylases (1994)
    Springer
    Chromatographia 38 (1994), S. 232-234 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Thiophilic interaction chromatography ; Hydrophobic interaction chromatography ; Salt-promoted adsorption ; Malted barley amylases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A sequence for the fractionation of the amylasic components from a malted barley extract is proposed using two salt-promoted, adsorption processes: thiophilic interaction chromatography (TIC) and hydrophobic interaction chromatography (HIC). Two fractions containing α-amylase activity were recovered during the thiophilic chromatography; the first was resolved in to α-amylase I and β-amylase I by HIC on a phenyl-sepharose column; an enrichment factor of 32 was achieved for α-amylase I. The other amylasic component eluted from the thiophilic gel was characterized as α-amylase II. Although the adsorption of malt amylases on phenylsepharose and the thiophilic adsorbent is salt promoted, the interactions involved in each case are clearly distinguished by the different behaviour and disparate salt effects.
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    Syntheses of spherical silica and titania from alkoxides on a laboratory scale (1994)
    Springer
    Chromatographia 38 (1994), S. 291-294 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Column packings ; Silica and titania ; Sol-gel method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A process to synthesize silica and titania as spherical packing materials has been investigated on the laboratory scale by the sol-gel method. The silica and titania obtained were tested under normal-phase separation conditions for comparison of their retention characteristics silica witha a commercial. The silica was found to be similar in its retention behaviour to the commercial silica. The titania showed basic properties and strongly retained acidic compounds.
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    Liquid chromatography of cyclodextrins with indirect photometric detection of phenolphthalein inclusion complexes (1994)
    Springer
    Chromatographia 38 (1994), S. 453-455 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Cyclodextrins ; Inclusion complexation ; Indirect photometric detection ; Octadecyl-bonded poly(vinylalcohol) packings
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary β- and γ-cyclodextrin (CD) separated by liquid chromatography have been indirectly detected by depression of the background absorbance at a visible wavelength by means of inclusion complexation with phenolphthalein. The background signal was generated by phenolphthalein in an alkaline medium. Octadecyl-bonded poly(vinylalcohol) packings were employed as the stationary phase, which allowed the use of alkaline mobile phases, and eliminated post column mixing of reagents. The detection limits for β- and γ-CD were 0.1–0.5 μM at a signal to noise ratio of 3. α-CD could not be measured by the present detection principle.
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    Synthesis and characterization of phenylpropanolamine bonded silica for multimode liquid chromatography of small molecules (1994)
    Springer
    Chromatographia 38 (1994), S. 485-490 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Multimode chromatography ; Inorganic anions ; Organic acids ; Drugs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A multimodal silica support carrying both anionexchange and hydrophobic functions was prepared by bonding phenylpropanolamine to epoxysilane-modified silica. This support was characterized with regard to its physical and chromatographic properties and has a surface coverage of 150 μmol g−1. The reversed-phase and the anion-exchange behaviour of the new stationary phase were investigated by injection of acidic, neutral and basic drugs and inorganic anions. The retention of the tested compounds was manipulated by modifying the pH and proportion of organic modifier in the mobile phase in isocratic mode. The mixed-mechanism column provided a flexible and versatile method for the simultaneous separation of neutral, acidic and basic compounds.
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    Relationship between retention behavior and molecular structure in HPLC. Correlation between solubility parameter and molecular properties (1994)
    Springer
    Chromatographia 38 (1994), S. 599-608 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Solubility parameters ; Structure parameters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The application and significance of the solubility parameter are detailed for chromatographic systems. A critical review of the general concept and several empirical and semi-empirical equations for the solubility parameter are reported. Using the basic theory and a systematic study of the main factors affecting total (or expanded) solubility parameters (δT) along with boiling points and molar volumes, we found correlations between four kinds of solubility parameter obtained by different methods, which unify their calculation and establish an equation for the calculation of δT, successfully applying it to retention prediction in GC and LC. The results show our approach is more accurate and simplifies to a two-parameter model involving fundamental physicol-chemical parameters. In addition, the variation of δT with the carbon number of homologous series was investigated, mathematical models were derived by multi-regression analysis.
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    URL: http://dx.doi.org/10.1007/BF02277161
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    Separation of L-(+)-ascorbic and D-(−)-isoascorbic acids on multimodal phenylpropanolamine-coated silica (1994)
    Springer
    Chromatographia 38 (1994), S. 609-612 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Multimodal chromatography ; L-(+)-ascorbic and D-(−)-isoascorbic acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A mixture of L-(+)-ascorbic acid and its epimer, D-(−)-isoascorbic acid, have been separated on a phenylpropanolamine-coated silica support using multimodal chromatography. The retention order of the diastereoisomers is the same as that found in reversed-phase mode in which ionic interaction is predominant. Applications of such columns to the analysis of L-(+)-ascorbic acid in an ascorbic acid injection formulation and an orange juice sample are vigen.
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    URL: http://dx.doi.org/10.1007/BF02277162
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    Determination of 6-amino-2,2-dimethyl-1,3-dioxepan-5-ol by postcolumn derivatization witho-phthalaldehyde/2-mercapto-ethanol after ion-pair chromatography (1994)
    Springer
    Chromatographia 38 (1994), S. 479-484 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; o-Phthalaldehyde ; Postcolumn derivatization ; Fluorescence detection ; Validation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A high-performance liquid chromatographic method is discribed for the determination of 6-amino-2,2-dimethyl-1,3-dioxepan-5-ol using Spherisorb ODS II stationary phase and mobile phase 30:70 (v/v) methanol: aqueous 1-octane sulfonic acid. Detection was fluorimetric following postcolumn derivatization with o-phthaladehyde/2-mercaptoethanol. The procedure was applied to the analysis of aqueous solutions and microcrystalline suspensions in liquid paraffin, prepared for investigation of the toxicological profile. The method was validated for selectivity, linearity of detector response, repeatability, limit of detection and quantitation. The HPLC method was selective. The instrumental limit of detection was 0.5 ng per injection (0.05 μg mL−1). The method detection limits were 0.5 μg mL−1 aqueous solution and 5 μg mL−1 liquid paraffin suspension, the quantitation limit 0.05 mg mL−1 aqueous solution and 1.0 mg mL−1 liquid paraffin. Linearity was within 0.94–47.1 μg mL−1. Intra-assay accuracy accounted for 99–100% in the range 0.05–226 mg mL−1 aqueous solution, intra-assay precision for 2% (C.V.). For microcrystalline liquid paraffin suspensions with 1 and 250 mg mL−1 99 and 109% was found for intra-assay accuracy. Intra-assay precision was 5% (C.V.). Reliable results over a wide concentration range can be obtained. The procedure is considered valid for determination of the analyte in aqueous solution or microcrystalline paraffin oil suspensions.
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    URL: http://dx.doi.org/10.1007/BF02269840
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    Use of porous graphitized carbon column for determining taxol inTaxus baccata (1994)
    Springer
    Chromatographia 39 (1994), S. 740-742 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Porous graphitized carbon ; Taxol ; Taxus baccata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Porous graphitized carbon columns have been used for the separation and quantitative determination of the anticancer drug taxol in the bark and foliage ofTaxus baccata. Successful separations were achieved using water∶dioxane 54∶46 v/v eluent. Peak purity tests and the spectra of taxol peaks taken at different retention times indicated that the taxol peak is not entirely homogeneous and probably contains other taxoteres coeluted with the main compound.
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    URL: http://dx.doi.org/10.1007/BF02274591
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    Chromatographic and related studies of alkylamide phases (1994)
    Springer
    Chromatographia 39 (1994), S. 155-161 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chemically bonded phase (CBP) ; Alkylamide phase ; Surface characterization ; Thermal stability ; Packings evaluation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A series of chemically bonded phases has been prepared with amide groups localized by means of hydrophobic ligands. The physicochemical and chromatographic properties of such phases with chain lengths ranging from C5 to C8 have been examined by porosimetry, elemental analysis, solid-state NMR, and liquid chromatography. Subsequently, the conformational dynamics of these phases have been investigated by analyzing the dependence of the capacity factor (k) on the reciprocal of temperature for different organic compounds. Special emphasis has been given to the reproducibility of retention data obtained before and after temperature-dependent measurements.
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    URL: http://dx.doi.org/10.1007/BF02274494
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    Enantiomeric separation of amphetamine, methamphetamine and ring substituted amphetamines by means of a β-cyclodextrin-chiral stationary phase (1994)
    Springer
    Chromatographia 39 (1994), S. 131-137 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral separation ; Amphetamine ; Cyclodextrin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The enantioseparation of amphetamine, methamphetamine and various ring-substituted amphetamines by use of a chiral stationary phase carrying immobilized native β-cyclodextrin (β-CyD) selectors is reported. The system is evaluated for resolving the specified compounds directly without any derivatization and after derivatization with phenyl isothiocyanate (PITC), naphthyl isothiocyanate (NITC) and 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC). This direct enantioseparation is compared with the features of indirect separation of diasteromeric derivatives after reaction with the optically pure Marfey's reagent employing a simple non-chiral alkyl-silica (RP-8) column. A selection of those methods best suited for each single amphetamine is given. Seventeen different samples of amphetamine, confiscated by the Swedisch police, were analyzed with respect to their enantiomeric composition. Within this set of samples synthesized by the same method no significant deviation from a racemic ratio could be observed.
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    URL: http://dx.doi.org/10.1007/BF02274491
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    Separation of polycyclic aromatic hydrocarbons under isocratic conditions by a column switching technique (1994)
    Springer
    Chromatographia 39 (1994), S. 175-179 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Column switching ; Columns at different temperatures ; Polycyclic aromatic hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple and efficient method of separating a 20-component PAH-mixture (RSM 1647 standard mixture +benzene, toluene, perylene and coronene) by RP-HPLC is described. Separation was by using two Superspher-100 RP-18 cartridges thermostatted at different temperatures under isocratic conditions with water-acetonitrile eluent. The analysis time with complete resolution of all components can be reduced to 15 min.
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    URL: http://dx.doi.org/10.1007/BF02274497
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    Validation of a strategic approach to high-performance liquid chromatographic method selection (1994)
    Springer
    Chromatographia 39 (1994), S. 339-345 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; First-guess ; Retention optimization ; Validation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A recently reported chromatographic method selection strategy has been validated using fifteen drug formulations selected randomly from the Belgium Compendium, 1992. On the basis of the hydrophobic and the acidic — basic properties of the sample components, reversed-phase was recommended as the first choice mode for all formulations. For two multicomponent formulations the range of analyte polarity dictated the need for gradient elution. The commerical software DryLab G/plus® was used for selection of optimum gradient conditions. The results obtained by both isocratic and gradient chromatography are discussed, as is the usefulness of a tailing suppressor in both modes.
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    URL: http://dx.doi.org/10.1007/BF02274523
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    Analysis of oligonucleotides using coupled high performance liquid chromatography-electrospray mass spectrometry (1994)
    Springer
    Chromatographia 39 (1994), S. 405-408 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Electrospray mass spectrometry ; Oligonucleotides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Improved HPLC and ESMS conditions have been established, allowing the separation and analysis of oligodesoxyribonucleotides by coupled HPLC-ESMS.
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    URL: http://dx.doi.org/10.1007/BF02278754
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    Chemical analysis of microcystins RR and LR in cyanobacterium using a prepacked cyano cartridge (1994)
    Springer
    Chromatographia 39 (1994), S. 427-430 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Microcystins RR and LR ; Solid phase extraction ; Cyano cartridges
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new method for the determination of microcystins PR and LR in cyanobacterium was developed using cyano-type prepacked cartridges. The microcystins were extracted with 10% acetic acid and the extract applied to a Baker 10 cyano cartridge. After elution from the cartridge with 0.5M acetic acid-acetonitrile (1∶9) the microcystins were determined by HPLC. Better recoveries and chromatograms were observed than with ODS cartridges.
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    URL: http://dx.doi.org/10.1007/BF02278757
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    The lipocalin model for human orosomucoid: Support from the chromatography of orosomucoid-monoclonal antibody complexes (1994)
    Springer
    Chromatographia 39 (1994), S. 475-480 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Orosomucoid ; α1-acid glycoprotein ; Lipocalin ; Monoclonal antibodies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The accessibility of the surface of human orosomucoid to monoclonal antibodies (MAbs) was investigated by size-exclusion HPLC to examine the validity of its proposed membership in the lipocalin family. The N-terminus half of the molecule contains all the five glycan chains, and of fifty-six MAbs, only one bound to this piece of the polypeptide backbone, indicating that extensive screening was taking place. The simultaneous binding properties of selected MAbs to the fully glycosylated molecule was examined by size exclusion HPLC. The pattern of inhibition was contiguous, with all regions being overlapped. The epitopes of four MAbs having mutual noncompetitive binding were found to be appropriately spaced when placed on a preliminary three dimensional model of orosomucoid. Together, the results support a structure for orosomucoid composed of an exposed continuous protein surface, and a glycan surface screening the remaining protein. Such a structure is provided by the antiparallel β-barrel motif of the lipocalins.
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    URL: http://dx.doi.org/10.1007/BF02278765
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    Simultaneous determination of dexamethasone and betamethasone in pharmaceuticals by reversed-phase HPLC (1994)
    Springer
    Chromatographia 39 (1994), S. 539-542 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Glucocorticoids ; Betamethasone and dexamethasone ; Pharmaceuticals ; Tablet preparations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An HPLC method for the simultaneous determination of the glucocorticoids betamethasone and dexamethasone is described. The method based on the separation of these compounds using a binary watertetrahydrofuran mobile phase and a reversed-phase Hypersil C18 column, was applied to the determination of betamethasone and dexamethasone in tablets.
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    URL: http://dx.doi.org/10.1007/BF02268276
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    Chromatography in our investigations of camomile (Matricaria chamomilla L.) (1994)
    Springer
    Chromatographia 39 (1994), S. 587-590 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; GC-MS ; Thin-layer chromatography ; Essential oils ; Matricaria chamomilla L
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Chromatographic methods for qualitative and quantitative analysis of non-volatile and volatile compounds of camomile (Matricaria chamomilla L.) are described. For determination of flavonoids of the apigenin series HPTLC and HPLC were used. To obtain standard samples of components of camomile oil semi-preparative TLC was used. Mass spectra of these standards were obtained to provide a data base. Qualitative and quantitative analysis of camomile oil compounds by GC-MS was then possible.
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    URL: http://dx.doi.org/10.1007/BF02268284
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    High-performance liquid chromatographic determination of cymiazole in honey with UV and electrochemical detection (1994)
    Springer
    Chromatographia 39 (1994), S. 602-606 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Narrow bore columns ; Cymiazole ; Honey ; Solid-phase extraction ; UV and electrochemical detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An HPLC method for determination of cymiazole in honey using a narrow bore C18 column is described. Preconcentration and sample cleaning were achieved by using solid-liquid extraction with SCX Bond Elut cartridges. The performance of UV and amperometric (EC) detector systems were also compared. The detection limits with UV and EC detectors were 1.7 and 0.7 μg kg−1 respectively. Average recoveries obtained with UV and EC detectors were 91.2% and 86.1% with a standard deviation of 3.8% and 12.5% respectively. In spite of its higher sensitivity the EC detector is not suitable for this type of analysis because of its lack of reproducibility and the long analysis time required.
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    URL: http://dx.doi.org/10.1007/BF02268287
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    Postprandial thermogenesis of rats with glutamate induced obesity in relation to energy intake (1993)
    Springer
    European journal of nutrition 32 (1993), S. 71-73 
    Details
    ISSN: 1436-6215
    Keywords: Rat ; glutamate-induced obesity ; postprandial thermogenesis ; Ratte ; Glutamat-induzierte Adipositas ; postprandiale Thermogenese
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung Bei 4 Monate alten Ratten mit Glutamat-induzierter Adipositas wurde die postprandiale Thermogenese über 8 h nach Fütterung von 300, 450 und 600 kJ/kg0,75 einer Pellet-Diät mittels indirekter Kalorimetrie in computergesteuerten Stoffwechselkäfigen mit offenem Kreislauf bestimmt. Bei den adipösen Tieren war die postprandiale Thermogenese nach Aufnahme von 600 kJ/kg0,75 (oberhalb des Energieerhaltungsbedarfs) signifikant auf 40% der Thermogenese der Kontrolltiere reduziert (12,0 gegenüber 31,5 kJ/kg0,75×8 h). Es wird geschlußfolgert, daß die Ratte mit Glutamat-induzierter Adipositas als ein Tiermodell mit beeinträchtigter fakultativer Thermogenese anzusehen ist, die hauptsächlich durch eine Verminderung der sympathischen adrenergen Aktivität verursacht ist.
    Notes: Summary Postprandial thermogenesis was estimated in 4-month-old male rats with glutamate induced obesity after being fed with 300, 450 and 600 kJ/kg0.75 of a pellet diet, respectively by indirect calorimetry in computer-controlled open circuit metabolic cages over 8 h. After an intake of 600 kJ/kg0.75 (above the maintenance energy requirement) postprandial thermogenesis was significantly reduced in the obese animals to about 40% of control rats (12.0 versus 31.5 kJ/kg0.75×8 h). It is concluded that the glutamate obese rat can be accepted as an animal model with impaired facultative thermogenesis, mainly caused by a reduction of sympathetic adrenergic activity.
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    URL: http://dx.doi.org/10.1007/BF01610087
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    Conserving genetic variability of a wild insect population under laboratory conditions (1993)
    Springer
    Entomologia experimentalis et applicata 67 (1993), S. 233-239 
    Details
    ISSN: 1570-7458
    Keywords: inbreeding ; colonization ; isofemale line ; Drosophila ; Diptera ; Leptopilina boulardi ; Cynipidae ; Hymenoptera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé D. melanogaster (Meigen) a été utilisé pour tester la capacité des lignées isofemelles à conserver la variabilité génétique d'une population naturelle. Deux types d'expériences ont été réalisées. L'une a consisté à déterminer la variabilité génétique de 3 locus enzymatiques pour 32 lignées isofemelles à la première et à la 23ème génération d'élevage au laboratoire. L'autre a consisté à tester la capacité des larves à éliminer un parasitoïde par le processus d'encapsulation après 8 années d'élevage au laboratoire. D'une façon générale, certaines lignées isofemelles perdent de la variabilité durant les 23 générations de l'étude. Mais la fréquence globale des allèles reste inchangée si l'on considère l'ensemble des 32 lignées. Le seul allèle rare observé a également été conservé. Les modifications des fréquences allèliques à chacun des locus ont lieu de façon indépendante les unes des autres. La variabilité génétique d'un caractère biologique, la capacité des larves à encapsuler le parasitoïde, a également varié, mais elle a pu être restaurée à un niveau proche de la population initiale en rassemblant plusieurs individus de chacune des lignées.
    Notes: Abstract Drosophila melanogaster (Meigen) was used to test the power of isofemale lines in preserving genetic variability. We performed experiments in two ways. One series consisted of measuring the genetic variability for three enzymatic loci in 32 isofemale lines, in the first and 23rd generations of culture. In the second series, we tested the capacity of the larvae to eliminate a parasitoid by encapsulation after eight years of laboratory breeding. In general, individual isofemale lines appeared to change during the 23 generations of the study, but the global frequency of these alleles among the 32 isofemale lines stayed relatively unchanged. The only rare allele observed was also conserved. Changes in allozyme frequencies at any one locus were independent of those at other loci. Genetic variation of a biological trait, the capacity of the larvae to encapsulate a parasitoid, also changed, but it could be restored to a level close to that of the starting population by mass hybridizing together individuals of each line.
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    Responses of a generalist and a specialist parasitoid (Hymenoptera: Eucoilidae) to Drosophilid larval kairomones (1993)
    Springer
    Journal of insect behavior 6 (1993), S. 615-624 
    Details
    ISSN: 1572-8889
    Keywords: Hymenoptera ; Leptopilina ; Drosophila ; semiochemicals ; kairomones ; parasitoid ; generalist ; specialist ; foraging behavior
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Foraging parasitoids are thought to need more specific information than generalists on the presence, identity, availability, and suitability of their insect host species. In the present paper, we compare responses to host kairomones by two phylogenetically related parasitoid species that attack Drosophilidae and that differ in the width of their host range. As predicted, the behavioral response of the parasitoids to host kairomones reflected their difference in host range. The response of the specialist parasitoid Leptopilina boulardiwas restricted to contact kairomones from its natural hosts and one closely related species. In contrast, the generalist parasitoid Leptopilina heterotomaresponded to contact kairomones of a variety of Drosophilidae species.
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    URL: http://dx.doi.org/10.1007/BF01048127
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    Sexual isolation betweenDrosophila melanogaster females andD. simulans males. Male mating propensities versus success in hybridization (1993)
    Springer
    Cellular and molecular life sciences 49 (1993), S. 596-598 
    Details
    ISSN: 1420-9071
    Keywords: Drosophila ; hybridization ; male vigour ; male mating speed
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Genetic variation has been found in males of aD. simulans population for their eagerness to hybridize withD. melanogaster females. In a search for traits involved in this hybridization, males ofD. simulans were tested for mating speed and sexual vigour. Between-male differences were detected in both sexual traits, but no relationship was noticed between them, nor with the frequency of hybridization. Thus male mating propensities appear to be unrelated to the breakdown of sexual isolation between these sibling species.
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    URL: http://dx.doi.org/10.1007/BF01955171
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    Colocalization of cholesterol and hydroxyapatite in human atherosclerotic lesions (1993)
    Springer
    Calcified tissue international 52 (1993), S. 94-98 
    Details
    ISSN: 1432-0827
    Keywords: Atherosclerosis ; Calcification ; Hydroxyapatite ; Cholesterol ; Filipin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Cholesterol and calcium phosphate, the latter in the form of hydroxyapatite, accumulate in atherosclerotic lesions. In this report, we demonstrate that these organic and inorganic constitutents of lesions can accumulate together, closely associated in crystal agglomerates. Using the fluorescent cholesterol probe, filipin, we identified unesterified cholesterol that was associated with calcium granules in tissue sections of lesions. We also have shown that small crystallites of cholesterol can associate with preformed hydroxyapatite crystals in vitro. Scanning electron microscopy couple with energy-dispersive X-ray analysis demonstrated the physical association of many small crystallites of cholesterol with larger crystals of hydroxyapatite. These small crystallites of cholesterol associated with hydroxyapatite stained with filipin. This contrasted with the lack of filipin staining of unassociated larger cholesterol crystals or hydroxyapatite alone. How cholesterol and calcium come to be closely associated in crystal agglomerates within atherosclerotic lesions remains to be determined.
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    URL: http://dx.doi.org/10.1007/BF00308315
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    Sustained release of salmon calcitonin in vivo from lactide: Glycolide copolymer depots (1993)
    Springer
    Calcified tissue international 52 (1993), S. 361-364 
    Details
    ISSN: 1432-0827
    Keywords: Calcitonin ; Sustained release ; Copolymer depot ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Studies were carried out to determine whether monolithic depot formulations, prepared using lactide:glycolide copolymers, could be used to administer salmon calcitonin (sCT) to rats in vivo. Formulations containing 2, 5, or 10% (w/w) sCT were administered subcutaneously to female Wistar strain rats. Release of sCT was determined by measurement of peptide in plasma using a specific radioimmunoassay and by measurement of residual sCT in the depots after recovery at postmortem. Plasma calcium concentrations and cumulative weight gain of the animals were used to measure pharmacological effects of the released sCT. Release of sCT from the depots was controlled by the copolymer and was sustained for periods up to 10 days. However, the release of sCT from the depots did not significantly alter plasma calcium concentrations, and effects on cumulative weight gain were small and transient. Peptide loading of the formulations was shown to modify sCT release. Maximal release of sCT from depots containing 10% peptide occurred over a 7 to 14-day period postadministration, with 5% sCT release occurred between days 11 and 14, and with 2% sCT, the period of maximal release was between days 11 and 18. Release of peptide from the depots was essentially complete by 21 days postadministration irrespective of the peptide loading. These data suggest that lactide:glycolide copolymer depots may have application for the convenient clinical administration of sCT in metabolic bone diseases.
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    URL: http://dx.doi.org/10.1007/BF00310200
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    Mechanical properties, bone mineral content, and bone composition (collagen, osteocalcin, IGF-I) of the rat femur: Influence of ovariectomy and nandrolone decanoate (anabolic steroid) treatment (1993)
    Springer
    Calcified tissue international 53 (1993), S. 269-277 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Nandrolone decanoate ; Ovariectomy ; Bone mechanics ; IGF-I ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Nandrolone decanoate (ND) is an anabolic steroid with a positive effect on bone mass in osteoporotic patients. The mechanism of action, (i.e., reduction of bone resorption and/or Stimulation of bone formation), the ultimate effect on mechanical properties, and the most effective dosage are not yet clear. To address these issues, dose-related effects of the long-term effect of ND on Serum and bone biochemistry, bone mineral content, and bone mechanical properties in ovariectomized (OVX) rats (12 weeks old at the Start of the experiment) were Studied for 6 months. The results were compared with those obtained in agematched, intact, and OVX rats. OVX caused in the femur a significant increase in net periosteal bone formation and net endosteal bone resorption of bone collagen content and torsional strength, and of Serum alkaline phosphatase, osteocalcin, and insulin-like growth factor-I (IGF-I) levels, whereas cortical bone density and calcium/creatinine and phosphorus/creatinine in 24-hour urine were Significantly reduced. Treatment of OVX rats with 1 mg ND/14 days resulted in a Significant increase in periosteal bone formation, femur length, cortical and trabecular bone mineral content and density, torsion stiffness and Strength, and bone IGF-I content, and a decrease in Serum osteocalcin, urinary calcium/creatinine levels, and bone collagen content compared with OVX controls. The higher ND dosage of 2.5 mg/14 days did not improve the results. ND treatment did not reverse all changes induced by OVX to the level of the intact controls. These results indicate that ND acts as an antiresorptive drug and as a bone formation Stimulating drug. Furthermore, the increased bone mass and bone mineral density is associated with improved bone Strength and stiffness and the presence of an increased amount of IGF-I. IGF-I is a growth factor considered to play a role in the maintenance of normal skeletal balance by a paracrine or autocrine mechanism.
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    URL: http://dx.doi.org/10.1007/BF01320913
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    The effects of the aminobisphosphonate alendronate on thyroid hormone-induced osteopenia in rats (1993)
    Springer
    Calcified tissue international 53 (1993), S. 278-282 
    Details
    ISSN: 1432-0827
    Keywords: Hyperthyroidism ; Osteopenia ; Bisphosphonate ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Hyperthyroidism, either endogenous or iatrogenic, leads to increased bone turnover and osteopenia. This study was conducted to examine (1) whether thyroid hormone excess in rats causes bone changes similar to those seen in patients with hyperthyroidism, and (2) the effects of the aminobisphosphonate alendronate on the thyroid hormone-induced bone changes. Sprague-Dawley male rats, divided into four groups, received L-thyroxine (T4) 250 μg/kg/day (+T4) or vehicle (-T4) subcutaneously six times per week and alendronate 1.75 mg/kg (+ALN) or vehicle (-ALN) orally twice a week. Rats were sacrificed after 3 weeks of treatment, blood samples were analyzed for serum T4, triiodo-L-thyronine (T3), and osteocalcin, and the proximal tibiae were processed for histomorphometric analysis. Serum T4 and T3 levels measured 20–24 hours after the last injection were 2 to 2.5-fold higher in +T4 groups than in-T4 groups. Serum osteocalcin was significantly (P 〈 0.05) higher in +T4/-ALN group than in the other groups, which were not statistically different from each other. T4 treatment (+T4/-ALN) significantly decreased the amount of cancellous bone volume (-45%) and increased osteoid surface (+254%), osteoblast surface (+111%), and osteoclast surface (+176%) relative to control values. Alendronate increased the bone volume above control values in both T4-treated (+ T4/ +ALN) and untreated (-T4/ +ALN) rats, and prevented the T4-induced increase in bone turnover in +T4/+ALN rats. It is concluded that (1) excess thyroid hormone induces cancellous bone loss associated with high bone turnover in the rat, and (2) this bone loss can be prevented by alendronate through the inhibition of osteoclastic activity.
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    URL: http://dx.doi.org/10.1007/BF01320914
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    Homopolymer length variation in the Drosophila gene mastermind (1993)
    Springer
    Journal of molecular evolution 37 (1993), S. 483-495 
    Details
    ISSN: 1432-1432
    Keywords: Drosophila ; mastermind ; Gene comparison ; Triplet repeat ; Homopolymer ; Protein evolution ; Repeat length variation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Runs of identical amino acids encoded by triplet repeats (homopolymers) are components of numerous proteins, yet their role is poorly understood. Large numbers of homopolymers are present in the Drosophila melanogaster mastermind (mam) protein surrounding several unique charged amino acid clusters. Comparison of mam sequences from D. virilis and D. melanogaster reveals a high level of amino acid conservation in the charged clusters. In contrast, significant divergence is found in repetitive regions resulting from numerous amino acid replacements and large insertions and deletions. It appears that repetitive regions are under less selective pressure than unique regions, consistent with the idea that homopolymers act as flexible spacers separating functional domains in proteins. Notwithstanding extensive length variation in intervening homopolymers, there is extreme conservation of the amino acid spacing of specific charge clusters. The results support a model where homopolymer length variability is constrained by natural selection.
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    URL: http://dx.doi.org/10.1007/BF00160429
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    Molecular phylogeny of Drosophila based on ribosomal RNA sequences (1993)
    Springer
    Journal of molecular evolution 37 (1993), S. 525-543 
    Details
    ISSN: 1432-1432
    Keywords: Drosophila ; Zaprionus ; Phylogeny ; Ribosomal RNA sequences
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nucleotide sequences of 72 species of Drosophilidae were determined for divergent D1 and D2 domains (representing 200 and 341 nucleotides respectively in D. melanogaster) of large ribosomal RNA, using the rRNA direct sequencing method. Molecular phylogenetic trees were reconstructed using both distance and parsimony methods and the robustness of the nodes was evaluated by the bootstrap procedure. The trees obtained by these methods revealed four main lineages or clades which do not correspond to the taxonomical hierarchy. In our results, the genus Chymomyza is associated with the subgenus Scaptodrosophila of the genus Drosophila and their cluster constitutes the most ancient clade. The two other clades are constituted of groups belonging to the subgenus Sophophora of the genus Drosophila: the so-called Neotropical clade including the willistoni and saltans groups and the obscura-melanogaster clade itself split into three lineages: (1) obscura group + ananassae subgroup, (2) montium subgroup, and (3) melanogaster + Oriental subgroups. The fourth clade, the Drosophila one, contains three lineages. D. polychaeta, D. iri, and D. fraburu are branched together and constitute the most ancient lineage; the second lineage includes the annulimana, bromeliae, dreyfusi, melanica, mesophragmatica, repleta, robusta, and virilis groups. The third lineage is composed of the immigrans and the cardini, funebris, guaramunu, guarani, histrio, pallidipennis, quinaria, and tripunctata groups. The genera Samoaia, Scaptomyza, and Zaprionus are branched within the Drosophila clade. Although these four clades appear regularly in almost all tree calculations, additional sequencing will be necessary to determine their precise relationships.
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    URL: http://dx.doi.org/10.1007/BF00160433
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    Evolution of thedec-1 eggshell locus inDrosophila. II. Intraspecific DNA sequence analysis reveals length mutations in a repetitive region inD. melanogaster (1993)
    Springer
    Journal of molecular evolution 36 (1993), S. 536-544 
    Details
    ISSN: 1432-1432
    Keywords: Drosophila ; dec-1 eggshell gene ; Wild-type variants ; Repeated region ; DNA sequencing
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Thedec-1 eggshell gene inDrosophila melanogaster encodes follicle cell proteins required for proper eggshell assembly. As shown by Southern and Northern analyses thedec-1 gene occurs in four alleles (Fcl-4) among wild-type strains. Its second exon has a distinct feature in the form of 12 repeats with 78–91 nucleotides; the first five show nearly 100% homology. DNA sequence comparison of the repeated region of the alleles revealed that the length polymorphisms are caused by changes in the numbers of the first five repeats. The results suggest that the alleles have been generated by unequal intragenic crossing-over and/or slippage during DNA replication and that the allelic length variants have arisen independently. The possiblilty that the most common allele,FC1, has a selective advantage over the other alleles is discussed.
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    URL: http://dx.doi.org/10.1007/BF00556358
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    Conservation and change of the developmentally crucial fushi tarazu gene in Drosophila (1993)
    Springer
    Journal of molecular evolution 36 (1993), S. 315-326 
    Details
    ISSN: 1432-1432
    Keywords: Drosophila ; Fushi tarazu ; Functional constraints ; Regulatory elements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have studied the evolutionary changes occurring in the noncoding regions around the developmentally important fushi tarazu (ftz) gene in a total of 11 species in the genus Drosophila. Previous molecular developmental studies have identified DNA elements both 3′ and 5′ to the coding region which are important in proper regulation of expression of the Drosophila melanogaster ftz gene. We show here that these same elements are the most evolutionarily conserved regions in the vicinity of the gene homologs. Parts of some control elements are more conserved than exonic sequences. Not only is there sequence conservation, but the relative position, orientation, and distances among the control elements remain conserved. One quite significant difference does exist between the two major subgenera studied, Sophophora and Drosophila: namely, an inversion of the ftz unit with respect to other genes in the Antennapedia complex, ANT-C. As a comparison, we applied similar analysis to a “housekeeping” gene-rosy (ry), or Xdh. In contrast, DNA sequences 5′ to the ry coding region revealed little evolutionary conservation. These studies bear out the proposition that functionally important DNA sequences remain more conserved through evolutionary time than do less functionally important sequences. This proposition could be tested in the present case because we could predict a priori from the developmental studies which DNA regions should be most conserved.
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    URL: http://dx.doi.org/10.1007/BF00182179
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    Wavelength-dependent effects of light on magnetic compass orientation in Drosophila melanogaster (1993)
    Springer
    Journal of comparative physiology 172 (1993), S. 303-308 
    Details
    ISSN: 1432-1351
    Keywords: Drosophila ; Photoreception ; Magnetoreception ; Magnetic compass orientation ; Geomagnetic field
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract 1. Wildtype Oregon-R Drosophila melanogaster were trained in the ambient magnetic field to a horizontal gradient of 365 nm light emanating from one of the 4 cardinal compass directions and were subsequently tested in a visually-symmetrical, radial 8-arm maze in which the magnetic field alignment could be varied. When tested under 365 nm light, flies exhibited consistent magnetic compass orientation in the direction from which light had emanated in training. 2. When the data were analyzed by sex, males exhibited a strong and consistent magnetic compass response while females were randomly oriented with respect to the magnetic field. 3. When tested under 500 nm light of the same quantal flux, females were again randomly oriented with respect to the magnetic field, while males exhibited a 90° clockwise shift in magnetic compass orientation relative to the trained direction. 4. This wavelength-dependent shift in the direction of magnetic compass orientation suggests that Drosophila may utilize a light-dependent magnetic compass similar to that demonstrated previously in an amphibian. However, the data do not exclude the alternative hypothesis that a change in the wavelength of light has a non-specific effect on the flies' behavior, i.e., causing the flies to exhibit a different form of magnetic orientation behavior.
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    URL: http://dx.doi.org/10.1007/BF00216612
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    Gypsy homologous sequences inDrosophila subobscura (gypsyDS) (1993)
    Springer
    Journal of molecular evolution 36 (1993), S. 127-135 
    Details
    ISSN: 1432-1432
    Keywords: Transposable elements ; Drosophila ; Gypsy ; Horizontal transfer ; In situ hybridization ; Molecular evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Characterization of sequences homologous to theDrosophila melanogaster gypsy transposable element was carried out inDrosophila subobscura (gypsyDS). They were found to be widely distributed among natural populations of this species. From Southern blot and in situ analyses, these sequences appear to be mobile in this species.GypsyDS sequences are located in both euchromatic and heterochromatic regions. A completegypsyDS sequence was isolated from aD. subobscura genomic library, and a 1.3-kb fragment which aligns with the ORF2 of theD. melanogaster gypsy element was sequenced. Comparisons of this sequence in three species (D. subobscura, D. melanogaster, and D. virilis) indicate that there is greater similarity between theD. subobscura-D. virilis sequences than betweenD. subobscura andD. melanogaster. Molecular divergence ofgypsy sequences betweenD. virilis andD. subobscura is estimated at 16 MY, whereas the most likely divergence time of these two species is more than 60 MY. These data strongly suggest thatgypsy sequences have been horizontally transferred between these species.
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    URL: http://dx.doi.org/10.1007/BF00166248
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    Characterization of the length polymorphism in the A+T-rich region of the Drosophila obscura group species (1993)
    Springer
    Journal of molecular evolution 36 (1993), S. 214-223 
    Details
    ISSN: 1432-1432
    Keywords: Drosophila ; Mitochondrial DNA ; Length polymorphisms ; A+T-rich region ; Tandem duplicated sequences ; Nucleotide sequences ; Secondary structures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In the twelve Drosophila obscura group species studied, belonging to the affinis, obscura, and pseudoobscura subgroups, the mitochondrial DNA length ranges from 15.8 to 17.2 kb. This length polymorphism is mainly due to insertions/deletions in the variable region of the A+T-rich region. In addition, one species (D. tristis) possess a tandem duplication of a 470-bp fragment that contains the replication origin. The same duplication has occurred at least twice in the Drosophila evolutionary history due to the fact that the repetition is analogous to repetitions found in the four species of the D. melanogaster complex. By comparing the nucleotide sequence of the conserved region in D. ambigua, D. obscura, D. yakuba, D. teissieri, and D. virilis, we show the presence of a secondary structure, likely implied in the replication origin, which could favor the generation of this kind of duplications. Finally, we propose that the high A and T content in the variable region of the A + T-rich region favors the formation of less-stable secondary structures, which could explain the generation of minor insertion/deletions found in this region.
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    URL: http://dx.doi.org/10.1007/BF00160476
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    Functional conservation of a glucose-repressible amylase gene promoter from Drosophila virilis in Drosophila melanogaster (1993)
    Springer
    Journal of molecular evolution 36 (1993), S. 234-242 
    Details
    ISSN: 1432-1432
    Keywords: Drosophila ; Glucose repression ; Amylase gene ; Interspecific promoter function ; Conserved cis-acting elements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Previous studies have demonstrated that the expression of the α-amylase gene is repressed by dietary glucose in Drosophila melanogaster. Here, we show that the α-amylase gene of a distantly related species, D. virilis, is also subject to glucose repression. Moreover, the cloned amylase gene of D. virilis is shown to be glucose repressible when it is transiently expressed in D. melanogaster larvae. This cross-species, functional conservation is mediated by a 330-bp promoter region of the D. virilis amylase gene. These results indicate that the promoter elements required for glucose repression are conserved between distantly related Drosophila species. A sequence comparison between the amylase genes of D. virilis and D. melanogaster shows that the promoter sequences diverge to a much greater degree than the coding sequences. The amylase promoters of the two species do, however, share small clusters of sequence similarity, suggesting that these conserved cis-acting elements are sufficient to control the glucose-regulated expression of the amylase gene in the genus Drosophila.
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    URL: http://dx.doi.org/10.1007/BF00160478
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    Nucleotide divergence of the rp49 gene region between Drosophila melanogaster and two species of the Obscura group of Drosophila (1993)
    Springer
    Journal of molecular evolution 36 (1993), S. 243-248 
    Details
    ISSN: 1432-1432
    Keywords: rp49 gene ; Drosophila ; Sequence divergence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A 2.1-kb SStI fragment including the rp49 gene and the 3′ end of the δ-serendipity gene has been cloned and sequenced in Drosophila pseudoobscura. rp49 maps at region 62 on the tip of chromosome II of this species. Both the coding and flanking regions have been aligned and compared with those of D. subobscura. There is no evidence for heterogeneity in the rate of silent substitution between the rp49 coding region and the rate of substitutions in flanking regions, the overall silent divergence per site being 0.19. Noncoding regions also differ between both species by different insertions/deletions, some of which are related to repeated sequences. The rp49 region of D. pseudoobscura shows a strong codon bias similar to those of D. subobscura and D. melanogaster. Comparison of the rates of silent (K S ) and nonsilent (K a ) substitutions of the rp49 gene and other genes completely sequenced in D. pseudoobscura and D. melanogaster confirms previous results indicating that rp49 is evolving slowly both at silent and nonsilent sites. According to the data for the rp49 region, D. pseudoobscura and D. subobscura lineages would have diverged some 9 Myr ago, if one assumes a divergence time of 30 Myr for the melanogaster and obscura groups.
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    URL: http://dx.doi.org/10.1007/BF00160479
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    Evolution of regulatory genes and patterns: Relationships to evolutionary rates and to metabolic functions (1993)
    Springer
    Journal of molecular evolution 37 (1993), S. 590-599 
    Details
    ISSN: 1432-1432
    Keywords: Evolution ; Gene regulation ; Drosophila ; Adaptation ; Enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In an effort to understand the forces shaping evolution of regulatory genes and patterns, we have compared data on interspecific differences in enzyme expression patterns among the rapidly evolving Hawaiian picture-winged Drosophila to similar data on the more conservative virilis species group. Divergence of regulatory patterns is significantly more common in the former group, but cause and effect are difficult to discern. Random fixation of regulatory variants in small populations and/or during speciation may be somewhat more likely than divergence driven by selection. Within the picture-winged group, we also have compared enzymes that fulfill different metabolic roles. There are highly significant differences between individual enzymes, but no obvious correlations to functional categories.
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    URL: http://dx.doi.org/10.1007/BF00182745
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    An experimental model of ascending pyelonephritis due toCandida albicans in rats (1993)
    Springer
    Mycopathologia 123 (1993), S. 149-154 
    Details
    ISSN: 1573-0832
    Keywords: Ascending pyelonephritis ; Candida albicans ; Experimental model ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We developed a new experimental model of ascendingCandida pyelonephritis in female rats with leukopenia and vesicoureteral reflux. Rats were treated transperitoneally with cyclophosphamide (200 mg/kg) to induce leukopenia 3 days before and transurethrally with diluted acetic acid solution to induce vesicoureteral reflux 1 day before inoculation ofCandida albicans strain, ATCC 10259 (containing 107 cells). Microscopy revealed acute pyelonephritis in whichCandida cells invaded from the fornix and/or papilla into the medulla within 3 days after inoculation. Between 7 and 28 days after inoculation, chronic pyelonephritis reached the cortex. The incidence of pyelonephritis increased gradually and was approximately 80% after 7 days.Candida colony counts of bladder urine specimens obtained by direct puncture were significantly greater in rats with pyelonephritis extending into the parenchyma than in those with pyelonephritis located along the pelvis (p〈0.01). These results suggest that this rat model shows the characteristic feature of ascending pyelonephritis due toC. albicans and that the severity ofCandida pyelonephritis can be estimated fromCandida counts of bladder urine.
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    Developmental effects of monensin on Drosophila melanogaster (1993)
    Springer
    Development genes and evolution 203 (1993), S. 83-91 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; Monensin ; Extracellular matrix ; Membrane proteins ; Morphogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Extracellular matrix and membrane proteins and their correct secretion probably are key elements in morphogenesis and differentiation in Drosophila. In this study, we have analysed the effects of monensin, a Na+-H+-ionophore which blocks normal secretion, applied during cellular blastoderm formation on further development. Normal cell morphology and intercellular contacts are lost and the extracellular matrix becomes disorganized. Gastrulation is blocked and abnormal foldings can be observed. Cuticle phenotypes showed different degrees of ventral, dorsal, head and posterior defects. The results are discussed in the context of what is known about membrane and extracellular matrix proteins in Drosophila.
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    URL: http://dx.doi.org/10.1007/BF00539893
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    Developmental regulatory elements in the 5′ flanking DNA of the Drosophila choline acetyltransferase gene (1993)
    Springer
    Development genes and evolution 202 (1993), S. 159-169 
    Details
    ISSN: 1432-041X
    Keywords: Drosophila ; Choline acetyltransferase ; cis-Regulatory element ; lacZ reporter gene ; Colinergic neuron
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Choline acetyltransferase (ChAT, EC 2.3.1.6) catalyzes the production of the neurotransmitter acetylcholine, and is an essential factor for neurons to be cholinergic. We have analyzed regulation of the Drosophila ChAT gene during development by examining the β-galactosidase expression pattern in transformed lines carrying different lengths of 5′ flanking DNA fused to a lacZ reporter gene. The largest fragment tested, 7.4 kb, resulted in the most extensive expression pattern in embryonic and larval nervous system and likely reflects all the cis-regulatory elements necessary for ChAT expression. We also found that 5′ flanking DNA located between 3.3 kb and 1.2 kb is essential for the reporter gene expression in most of the segmentally arranged embryonic sensory neurons as well as other distinct cells in the CNS. The existence of negative regulatory elements was suggested by the observation that differentiating photoreceptor cells in eye imaginal discs showed the reporter gene expression in several 1.2 kb and 3.3 kb transformants but not in 7.4 kb transformants. Furthermore, we have fused the 5′ flanking DNA fragments to a wild type ChAT cDNA and used these constructs to transform Drosophila with a Cha mutant background. Surprisingly, even though different amounts of 5′ flanking DNA resulted in different spatial expression patterns, all of the positively expressing cDNA transformed lines were rescued from lethality. Our results suggest that developmental expression of the ChAT gene is regulated both positively and negatively by the combined action of several elements located in the 7.4 kb upstream region, and that the more distal 5′ flanking DNA is not necessary for embryonic survival and development to adult flies.
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    A late role for a subset of neurogenic genes to limit sensory precursor recruitments in Drosophila embryos (1993)
    Springer
    Development genes and evolution 202 (1993), S. 371-381 
    Details
    ISSN: 1432-041X
    Keywords: Neurogenesis ; Drosophila ; Neurogenic genes ; PNS ; Lineage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In Drosophila, mutations in a class of genes, the neurogenic genes, produce an excess of neurons. This neural hyperplasia has been attributed to the formation of more than the normal number of neuronal precursor cells at the expense of epidermal cells. In order to find out whether the neurogenic genes only act at this intial step of neurogenesis, we studied the replication pattern of the sensory organ precursor cells by monitoring BrdU incorporation in embryos mutant for Notch (N), Delta (Dl), mastermind (mam), almondex (amx), neuralized (neu), big brain (bib) and the Enhancer of split-Complex (E(spl)-C). Using temperature sensitive alleles of two of the neurogenic genes, DI and N, we also induced an acute increase of replicating sensory precursors by shifting briefly to the restricted temperature. We have found that the loss of function of all the seven neurogenic loci that were tested causes an increase in replicating sensory precursor cells, consistent with the model that these neurogenic genes normally participate in the process of restricting the number of neuronal precursors. Whereas the temporal pattern of replication appeared normal in mutants of five of the seven neurogenic loci, in N and mam embryos replicating PNS cells are present beyond the time when they normally undergo replication. Experiments with colchicine suggest that many of these late replicating cells may be newly emerging precursors and probably not additional cell divisions of already recruited precursors. Thus, different neurogenic genes may be required over different periods of time for the specification of sensory precursor cells.
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    Tracing neurons with a kinesin-β-galactosidase fusion protein (1993)
    Springer
    Development genes and evolution 202 (1993), S. 112-122 
    Details
    ISSN: 1432-041X
    Keywords: Axon guidance ; Drosophila ; Enhancer trap ; Kinesin-lacZ ; Neural development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have analyzed the development of neuronal projections inDrosophila by fusing the gene encodingDrosophila kinesin, a microtubule-associated motor protein, toEscherichia coli lacZ, and employing the resulting chimeric protein as a reporter molecule for labelling cells by the “enhancer-trap” method. Expression of kinesin-β-galactosidase in neurons has afforded a detailed view of the morphologies and projections of neurons. The images of cells provided by this method will facilitate anatomical and genetic investigations of theDrosophila nervous system as well as other cell types.
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    Embryonic origin of the imaginal discs of the head of Drosophila melanogaster (1993)
    Springer
    Development genes and evolution 203 (1993), S. 60-73 
    Details
    ISSN: 1432-041X
    Keywords: Head development ; Eye-antenna disc ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The embryonic development of the primordia of the Drosophila head was studied by using an enhancer trap line expressed in these structures from embryonic stage 13 onward. Particular attention was given to the question of how the adult head primordia relate to the larval head segments. The clypeo-labral bud to the stage 13 embryo is located at a lateral position in the labrum adjacent to the labral sensory complex (“epiphysis”). Both clypeo-labral bud and sensory complex are located anterior to the engrailed-expression domain of the labrum. Throughout late embryogenesis and the larval period, the clypeo-labral bud forms integral part of the epithelium lining the roof of the atrium. The labial disc originates from the lateral labial segment adjacent to the labial sensory complex (“hypophysis”). It partially overlaps with the labial en-domain. After head involution, the labial disc forms a small pocket in the ventro-lateral wall of the atrium. The eye-antenna disc develops from a relatively large territory occupying the dorso-posterior part of the procephalic lobe, as well as parts of the dorsal gnathal segments. Cells in this territory are greatly reduced in number by cell death during stages 12–14. After head involution, the presumptive eye-antenna disc occupies a position in the lateral-posterior part of the dorsal pouch. Evagination of this tissue occurs during the first hours after hatching. In the embryo, no en-expression is present in the presumptive eye-antenna disc. en-expression starts in three separate regions in the third instar larva.
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    Larval parasitoid uses aggregation pheromone of adult hosts in foraging behaviour: a solution to the reliability-detectability problem (1993)
    Springer
    Oecologia 93 (1993), S. 145-148 
    Details
    ISSN: 1432-1939
    Keywords: Hymenoptera ; Eucoilidae ; Leptopilina heterotoma ; Infochemicals ; Kairomone ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Parasitoids that forage for herbivorous hosts by using infochemicals may have a problem concerning the reliability and detectability of these stimuli: host stimuli are highly reliable but not very detectable at a distance, while stimuli from the host's food are very detectable but generally not very reliable in indicating host presence. One solution to this problem is to learn to link highly detectable stimuli to reliable but not very detectable stimuli. Ample knowledge is available on how associative learning aids foraging parasitoids in the location of suitable microhabitats. However, in this paper we report on another solution to the reliability-detectability problem and present evidence for an essential, but as yet overlooked, aspect of Drosophila parasitoid ecology. For the first time it is shown that a parasitoid of Drosophila larvae spies on the communication system of adult Drosophila flies to locate potential host sites: naive parasitoids strongly respond to a volatile aggregation pheromone that is deposited in the oviposition site by recently mated female flies. Thus, the parasitoids resort to using highly detectable information from a host stage different from the one under attack (i.e. infochemical detour). The function and ecological implications of these findings are discussed.
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    URL: http://dx.doi.org/10.1007/BF00321204
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    Yeast single copy gene URP1 is a homolog of rat ribosomal protein gene L21 (1993)
    Springer
    Current genetics 23 (1993), S. 15-18 
    Details
    ISSN: 1432-0983
    Keywords: Yeast ; Rat ; Ribosomal protein ; 60S Ribosomal subunit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary This communication reports on a single-copy gene of Saccharomyces cerevisiae which is homologous to the rat ribosomal protein gene L21. The yeast and the rat genes show 59% identity in DNA sequences and in the predicted protein sequences. This yeast gene is, therefore, assumed to code for an as yet unassigned ribosomal protein (URP1). The URP1 open reading frame is 480 nucleotides long and can encode a protein of about Mr 18 200. Like most of the other known ribosomal protein genes, URP1 is interrupted by an intron in its 5′ terminal part and it is preceeded by upstream sequence elements which usually regulate transcription of these genes. Northern blot analysis reveals that the URP1 gene is actually expressed in vivo.
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    URL: http://dx.doi.org/10.1007/BF00336743
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  • 184
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    Female song preference and theperiod gene inDrosophila (1993)
    Springer
    Behavior genetics 23 (1993), S. 85-90 
    Details
    ISSN: 1573-3297
    Keywords: period gene ; Drosophila ; genetic coupling ; coevolution ; sexual selection ; female preference
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Psychology
    Notes: Abstract Mutations at theperiod (per) locus inDrosophila melanogaster alter rhythmic components of the male courtship song. We have examined the mating speed of females homozygous for mutantper alleles when presented with artificial mutant songs. Mutant females retain a preference for wild-type over mutant songs, thus male song and female preference are probably under separate genetic control. In contrast,per-mutant females from an established laboratory stock which had been maintained for nearly two decades appear to have an enhanced response to the corresponding mutant song in that they no longer discriminate against mutant song. These results are discussed in terms of the “genetic coupling” and “coevolution” theories of complementarity between male and female components of communication systems.
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    URL: http://dx.doi.org/10.1007/BF01067557
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    A novel ancestral protein ofDrosophila alcohol dehydrogenase inStreptomyces? (1993)
    Springer
    Biochemical genetics 31 (1993), S. 393-407 
    Details
    ISSN: 1573-4927
    Keywords: alcohol dehydrogenases ; protein evolution ; Drosophila ; Streptomyces
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Polyclonal antibodies raised against purifiedDrosophila alcohol dehydrogenase (ADH) were used in Western blot analyses to search for structurally and/or immunologically related proteins in prokaryotes and eukaryotes. No immunological-reactive protein was detected in a flesh fly, a locust, and butterflies. Immunological similarity with the 50-kDa PQQ-glucose dehydrogenase (GluDH)-B enzyme ofAcinetobacter calcoaceticus was found, but the cross-reactivity apparently is dependent on the high hydrophilic character of this protein. Antibodies against PQQ-GluDH did not recognizeDrosophila ADH. In five of seven species of the gram-positive soil bacteria actinomycetes tested, a protein approximately 28–30 kDa in subunit size was strongly recognized by α-DADH. It is probably not one of the two proteins with known homology toDrosophila ADH,viz., theactIII gene product and 20β-hydroxysteroid dehydrogenase. The protein is present in both the soluble and the pellet-membrane fraction of the cells. The protein has a late temporal expression in surface-grown cultures and, therefore, might be involved in secondary metabolism.
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    URL: http://dx.doi.org/10.1007/BF02396225
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    A correction for allele frequency estimates derived from isofemale lines (1993)
    Springer
    Biochemical genetics 31 (1993), S. 61-74 
    Details
    ISSN: 1573-4927
    Keywords: isofemale ; allele frequency estimation ; population structure ; allozyme ; microsatellites ; restriction fragment length polymorphisms ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Isofemale lines are commonly used inDrosophila and other genera for the purpose of assaying genetic variation. Isofemale lines can be kept in the laboratory for many generations before genetic work is carried out, and permit the confirmation of newly discovered alleles. A problem not realized by many workers is that the commonly used estimate of allele frequency from these lines is biased. This estimation bias occurs at all times after the first laboratory generation, regardless of whether single individuals or pooled samples are used in each well of an electrophoretic gel. This bias can potentially affect the estimation of population genetic parameters, and in the case of rare allele analysis it can cause gross overestimates of gene flow. This paper provides a correction for allele frequency estimates derived from isofemale lines for any time after the lines are established in the laboratory. When pooled samples are used, this estimator performs better than the standard estimator at all times after the first generation. The estimator is also insensitive to multiple inseminations. After the lines have drifted oneN e generations, multiple inseminations actually make the new estimator perform better than it does in singly inseminated females. Simulations show that estimates made using either estimator after the lines have drifted to fixation have a much greater error associated with their use than do those estimates made earlier in time using the correction. In general it is better to use corrected estimates of gene frequency soon after lines are established than to use uncorrected estimates made after the first laboratory generation.
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    URL: http://dx.doi.org/10.1007/BF00553601
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    Effects of the residue adjacent to the reactive serine on the substrate interactions ofDrosophila esterase 6 (1993)
    Springer
    Biochemical genetics 31 (1993), S. 259-278 
    Details
    ISSN: 1573-4927
    Keywords: serine esterase ; substrate interactions ; Drosophila ; acetylcholine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Esterase 6 fromDrosophila melanogaster is a carboxylesterase that belongs to the serine esterase multigene family. It has a basic histidine (His) at residue 187, adjacent to the reactive serine (Ser) at residue 188, whereas most other characterized members of the family have an acidic glutamate (Glu) in the equivalent position. We have used site-directedin vitro mutagenesis to replace the His codon of the esterase 6 gene with either Gln or Glu codons. The enzymes encoded by these active-site mutants and a wild-type control have been expressed, purified, and characterized. Substitution of Gln for His at position 187 has little effect on the biochemical properties of esterase 6, but the presence of Glu at this position is associated with three major differences. First, the pH optimum is increased from 7 to 9. Second, the mutant enzyme shows decreased activity for β-naphthyl esters andp-nitrophenyl acetate but has gained the ability to hydrolyze acetylthiocholine. Finally, the Gibb's free energy of activation for the enzyme is increased. These results suggest that residue 187 interacts directly with the substrate alkyl group and that this interaction is fully realized in the transition state. We further propose that the presence of His rather than Glu at position 187 in esterase 6 contributes significantly to its functional divergence from the cholinesterases and that this divergence is due to different interactions between residue 187 and the substrate alkyl group.
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    URL: http://dx.doi.org/10.1007/BF00553170
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    Effects of the residue adjacent to the reactive serine on the substrate interactions ofDrosophila esterase 6 (1993)
    Springer
    Biochemical genetics 31 (1993), S. 259-278 
    Details
    ISSN: 1573-4927
    Keywords: serine esterase ; substrate interactions ; Drosophila ; acetylcholine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Esterase 6 fromDrosophila melanogaster is a carboxylesterase that belongs to the serine esterase multigene family. It has a basic histidine (His) at residue 187, adjacent to the reactive serine (Ser) at residue 188, whereas most other characterized members of the family have an acidic glutamate (Glu) in the equivalent position. We have used site-directedin vitro mutagenesis to replace the His codon of the esterase 6 gene with either Gln or Glu codons. The enzymes encoded by these active-site mutants and a wild-type control have been expressed, purified, and characterized. Substitution of Gln for His at position 187 has little effect on the biochemical properties of esterase 6, but the presence of Glu at this position is associated with three major differences. First, the pH optimum is increased from 7 to 9. Second, the mutant enzyme shows decreased activity for β-naphthyl esters andp-nitrophenyl acetate but has gained the ability to hydrolyze acetylthiocholine. Finally, the Gibb’s free energy of activation for the enzyme is increased. These results suggest that residue 187 interacts directly with the substrate alkyl group and that this interaction is fully realized in the transition state. We further propose that the presence of His rather than Glu at position 187 in esterase 6 contributes significantly to its functional divergence from the cholinesterases and that this divergence is due to different interactions between residue 187 and the substrate alkyl group.
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    URL: http://dx.doi.org/10.1007/BF02401822
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    Sulfite sensitivity and sulfite oxidase actiivty inDrosophila melanogaster (1993)
    Springer
    Biochemical genetics 31 (1993), S. 375-391 
    Details
    ISSN: 1573-4927
    Keywords: Drosophila ; sulfite oxidase ; molybdenum ; MoCo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The relationship between sulfite oxidase (SO) and sulfite sensitivity inDrosophila melanogaster is addressed. Significant improvements to the SO assay have provided an investigative tool which can be applied to further studies of this molybdoenzyme. Using the second-instar larval stage ofD. melanogaster, we have shown a direct relationship between measured levels of sulfite oxidase activity and the organism's ability to withstand a sulfite challenge. Implementation of a sulfite-testing procedure confirmed the documented instability of sulfite in solution and may explain some of the conflicting results reported in the SO literature. Results of the tungstate-addition experiments confirm thatDrosophila SO is a molybdoenzyme and its activity was shown to be governed by three of the four loci known to affect more than one molybdoenzyme. The ability ofD. melanogaster to withstand the application of exogenous sulfites is shown to be dependent on sulfite oxidase activity.
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  • 190
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    A novel ancestral protein ofDrosophila alcohol dehydrogenase inStreptomyces? (1993)
    Springer
    Biochemical genetics 31 (1993), S. 393-407 
    Details
    ISSN: 1573-4927
    Keywords: alcohol dehydrogenases ; protein evolution ; Drosophila ; Streptomyces
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Polyclonal antibodies raised against purifiedDrosophila alcohol dehydrogenase (ADH) were used in Western blot analyses to search for structurally and/or immunologically related proteins in prokaryotes and eukaryotes. No immunological-reactive protein was detected in a flesh fly, a locust, and butterflies. Immunological similarity with the 50-kDa PQQ-glucose dehydrogenase (GluDH)-B enzyme ofAcinetobacter calcoaceticus was found, but the cross-reactivity apparently is dependent on the high hydrophilic character of this protein. Antibodies against PQQ-GluDH did not recognizeDrosophila ADH. In five of seven species of the gram-positive soil bacteria actinomycetes tested, a protein approximately 28–30 kDa in subunit size was strongly recognized by α-DADH. It is probably not one of the two proteins with known homology toDrosophila ADH,viz., theactIII gene product and 20β-hydroxysteroid dehydrogenase. The protein is present in both the soluble and the pellet-membrane fraction of the cells. The protein has a late temporal expression in surface-grown cultures and, therefore, might be involved in secondary metabolism.
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    Sulfite sensitivity and sulfite oxidase actiivty inDrosophila melanogaster (1993)
    Springer
    Biochemical genetics 31 (1993), S. 375-391 
    Details
    ISSN: 1573-4927
    Keywords: Drosophila ; sulfite oxidase ; molybdenum ; MoCo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The relationship between sulfite oxidase (SO) and sulfite sensitivity inDrosophila melanogaster is addressed. Significant improvements to the SO assay have provided an investigative tool which can be applied to further studies of this molybdoenzyme. Using the second-instar larval stage ofD. melanogaster, we have shown a direct relationship between measured levels of sulfite oxidase activity and the organism's ability to withstand a sulfite challenge. Implementation of a sulfite-testing procedure confirmed the documented instability of sulfite in solution and may explain some of the conflicting results reported in the SO literature. Results of the tungstate-addition experiments confirm thatDrosophila SO is a molybdoenzyme and its activity was shown to be governed by three of the four loci known to affect more than one molybdoenzyme. The ability ofD. melanogaster to withstand the application of exogenous sulfites is shown to be dependent on sulfite oxidase activity.
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    Transfer of dye among salivary gland cells is not affected by genetic variations of the period clock gene in Drosophila melanogaster (1993)
    Springer
    The journal of membrane biology 136 (1993), S. 333-342 
    Details
    ISSN: 1432-1424
    Keywords: Drosophila ; per mutants ; pertransgenic ; Lucifer Yellow injections ; Gap junctions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Larval salivary gland cells of Drosophila melanogaster were injected with a fluorescent dye to assess strengths of intercellular communication among such cells, as influenced by mutations at the period locus and by a per transgene. This clock gene had been reported to increase the extent of dye transfer when mutated such that it shortens the period of biological rhythms; the previous study also showed that a per-null mutant decreased the strength of transfer among salivary gland cells. Our re-examination of this feature of larval physiology—in observer-blind analyses, using the per s and per o mutants as well as two per-normal strains—revealed no appreciable differences in extents of dye transfer among these four genotypes. These results are discussed in the context of emerging findings which suggest that the period gene's product controls pacemaker functioning as an intracellularly acting entity.
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    URL: http://dx.doi.org/10.1007/BF00233672
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    Operational sex ratios and sperm limitation in populations of Drosophila pachea (1993)
    Springer
    Behavioral ecology and sociobiology 33 (1993), S. 383-391 
    Details
    ISSN: 1432-0762
    Keywords: Operational sex ratio ; Maxim system ; Sperm ; Age of maturity ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Males of the cactophilic fruitfly, Drosophila pachea, produce relatively few but very large sperm, and partition their limited gamete numbers among successive mates. The present study found that males take 10 days longer than females, post-eclosion, to become sexually mature. The pattern of testes development suggests that the need to produce testes long enough to manufacture the giant sperm is the cause of the delayed male maturity. These findings generate the prediction that the operational sex ratio (OSR) of populations will be female-biased. The size, sex ratio, and OSR of natural populations were examined. In general, local populations tended to be small and sex ratios tended to be slightly male-biased. However, as predicted, the OSR of populations, at least in one season, tended to be female-biased, with an average of 2.3 receptive females for each sexually active male. Results of laboratory experiments to determine the relationship between female remating frequency and fitness, and between population OSR and productivity, suggest that natural populations with female-biased OSRs are sperm-limited. The origin and maintenance of sperm gigantism and the unusual sperm-partitioning behavior of males are discussed with respect to population structure.
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    URL: http://dx.doi.org/10.1007/BF00170253
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  • 194
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    Neurofilaments in rat and cat spinal cord; a comparative immunocytochemical study of phosphorylated and non-phosphorylated subunits (1993)
    Springer
    Cell & tissue research 272 (1993), S. 249-256 
    Details
    ISSN: 1432-0878
    Keywords: Spinal cord ; Motoneurones ; Dorsal horn ; Neurofilament ; Phosphorylation ; Immunocytochemistry ; Rat ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Neurofilament immunoreactivity was examined in spinal cords of rats and cats with antibodies to all three subunits (68 kD, 155 kD and 200 kD) and to different phosphorylation states of 200 kD. NFHP-, an antibody against non-phosphorylated 200 kD, labelled all rat neuronal perikarya but failed to labet cat neurofilaments. In both species, the perikarya and processes of motoneurones were immunoreactive for all three subunits but most dorsal horn neuronal perikarya were not immunoreactive for 68 kD and 155 kD. Motoneuronal perikarya and proximal processes showed filamentous labelling for 68 kD but not for 155 kD in the rat, while in neither species did these show labelling with RT97, an antibody against a highly phosphorylated form of 200 kD; immunoreactivity for 200 kD was present in both filamentous (probably partially phosphorylated) and non-filamentous (non-phosphorylated) forms, but in dorsal horn neurones only the latter was present. Interpretations consistent with this data are: in rat and possibly also cat, motoneuronal neurofilaments consist of a 68 kD backbone with partially phosphorylated 200 kD sidearms, with both 155 kD and 200 kD (non-phosphorylated) subunits in a non-filamentous form; this neurofilament becomes more highly phosphorylated along the proximal processes. The dorsal horn neurones probably contain 200 kD in a non-filamentous form but may lack the other subunits.
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    Microliths in normal salivary glands of cat investigated by light and electron microscopy (1993)
    Springer
    Cell & tissue research 272 (1993), S. 321-327 
    Details
    ISSN: 1432-0878
    Keywords: Calcification ; Calcinosis ; Calculi ; Microliths ; Salivary gland calculi ; Salivary glands ; Cat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract This investigation concerns the natural history of microlith in the salivary glands of cat. Microliths were detected in more sublingual than submandibular glands and were almost absent in the parotid. They were found intraparenchymally, intraluminally and interstitially, and ultrastructurally in phagosomes of acinar, ductal and myoepithelial cells, intermixed with the cytoplasm of degenerate acinar cells, and in intraparenchymal macrophages and a multinuclear giant cell. They appear to form in healthy acinar cells during autophagocytosis, and possibly to be discharged luminally, laterally or basally, and to form in the debris of degenerate cells intraparenchymally and intraluminally. They appear to be removed by expulsion in the saliva, scavenging macrophages, and possible eventual degradation in the parenchymal phagosomes. The greater occurrence of microliths in the sublingual gland may relate to a low level of secretory activity, and the near absence of microliths in the parotid to a low level of calcium. The feline salivary glands were found to be an outstanding model for the investigation of microlithiasis.
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    Confocal laser scanning light microscopy of the extra-thecal epithelia of undecalcified scleractinian corals (1993)
    Springer
    Cell & tissue research 272 (1993), S. 533-543 
    Details
    ISSN: 1432-0878
    Keywords: Mucocytes ; Calcification ; Intercellular spaces ; Zooxanthellae ; Calicoblastic ectoderm ; Confocal laser scanning microscopy ; Freeze-substitution ; Corals: Galaxea fascicularis, Acropora formosa, Tubastrea faulkneri (Cnidaria)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The extra-thecal epithelia of cryofixed undecalcified, freeze-substituted polyps of the scleractinian corals Galaxea fascicularis and Tubastrea faulkneri and axial and basal polyps of Acropora formosa have been examined, in anhydrously prepared thick slices, by confocal laser scanning light microscopy. The avoidance of chemical fixation and decalcification makes it possible to determine whether previously seen structures are real or artefactual products of swelling, shrinkage and distortion. All of the epithelia of all the corals examined are characterised by well defined intercellular spaces. Mucocytes are present in all cell layers in Galaxea and Tubastrea but are not present in any cell layers in the axial polyp of Acropora although they are abundant in the oral ectoderm of the basal polyps in this coral. Zooxanthellae are absent in Tubastrea, the epithelia of the exert septa of Galaxea and the axial polyp of Acropora. The calicoblastic ectoderm is generally composed of thin squamous cells with large intercellular spaces. At rapidly calcifying regions such as the tips of the exert septa of Galaxea, the calicoblastic cells are elongated with extensive arborisation of the basal regions of the cells. They are separated by large intercellular spaces and contain numerous fluorescent granules. The apical regions of these cells appear to be closely applied to the surface of the skeleton. There is no evidence of a space between the apical region of the calicoblastic cells and the skeleton.
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    Immunohistochemical localization of insulin-like growth factor 1 and 2 in the endocrine pancreas of rat, dog, and man, and their coexistence with classical islet hormones (1993)
    Springer
    Cell & tissue research 273 (1993), S. 249-259 
    Details
    ISSN: 1432-0878
    Keywords: Endocrine pancreas ; IGF-1 ; IGF-2 ; Insulin ; Glucagon ; Somatostatin ; Pancreatic polypeptide ; Man ; Dog ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Immunohistochemical techniques were used to study the occurrence and distribution of insulin-like growth factor 1 (IGF-1) and IGF-2 in the pancreas of man, dog, and rat and their possible coexistence with insulin (INS), glucagon (GLUC), somatostatin (SOM) and pancreatic polypeptide (PP). All control experiments, including pre-absorption of the antisera with synthetic peptide hormones, indicated the specificity of the immunoreactions obtained. In all species investigated, IGF-2-immunoreactivity occurred exclusively in INS-immunoreactive cells as was found by the use of consecutive sections and double immunofluorescence on identical sections. In contrast, IGF-1-immunoreactivity co-existed with GLUC-immunoreactivity. In man, singular SOM-immunoreactive cells also contained IGF-1-immunoreactivity. Thus, IGF-1 and IGF-2 can be localized by means of immunohistochemistry in the mammalian pancreas, and can be shown to occur in different islet cell populations. It is presumed that IGF-1 derived from A-cells and/or D-cells acts on the B-cells in a paracrine manner. The co-existence of IGF-2-immunoreactivity and INS-immunoreactivity in the human, rat, and dog endocrine pancreas indicates that mammalian IGF-2 and INS genes are regulated simultaneously.
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    URL: http://dx.doi.org/10.1007/BF00312826
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    Atrial natriuretic peptide binding in rat placenta, yolk sac, decidua, and materal placental vessels (1993)
    Springer
    Cell & tissue research 272 (1993), S. 391-394 
    Details
    ISSN: 1432-0878
    Keywords: ANP binding ; Yolk sac ; Decidua ; Maternal placental vessels ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Using in vitro autoradiography, binding sites of 125I-ANP (atrial natriuretic peptide) were localized in the rat placenta, visceral yolk sac, and decidua at 16, 18, and 20 days of gestation. There was diffuse binding over the labyrinthine region of the placenta and an intense binding over the decidual gland and visceral yolk sac. In the yolk sac, ANP localized over the cores of the villi where it may be involved with the regulation of transport across the membranes or the flow of blood through the vitelline vessels. Of particular interest was binding over the maternal blood vessels supplying the decidual region and placenta. Receptors were located on the endothelial cells and smooth muscle cells of the arteries and veins, indicating that ANP may be involved with regional regulation of blood flow to the placenta.
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    Seasonal localization of a collagenous protein in the organic matrix of spicules from the gorgonian Leptogorgia virgulata (Cnidaria: Gorgonacea) (1993)
    Springer
    Cell & tissue research 273 (1993), S. 309-316 
    Details
    ISSN: 1432-0878
    Keywords: Spicule ; Calcification ; Organic matrix ; Collagen ; Leptogorgia virgulata (Cnidaria)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Spicules of the gorgonian Leptogorgia virgulata possess an insoluble matrix fraction that is predominantly collagenous in summer months. This collagenous component is largely absent in winter months. Using an antibody directed against the 140 kD collagenous protein (CP) of the insoluble matrix, immuno-gold labelling was employed to localized this protein at the transmission electron-microscopy level throughout the year, and in different areas of the gorgonian colonies. Within the tip regions, the 140 kD CP varied throughout the year in the spicules, electron-dense bodies (EDBs) of scleroblasts, polyp vesicles, desmocytes and axes. In the mid and base regions, the 140 kD CP varied throughout the year in the spicules, EDBs and lysosomes of scleroblasts, desmocytes and axes. This variation in the location and density of the label suggests a dynamic annual cycling of the collagenous component of the insoluble matrix. EDBs may transport a collagenous component of the matrix to the spicule-forming vacuole. A component of the 140 kD CP may be transported and/or degraded by polyp vesicles and lysosomes, respectively. The pattern of labelling of the axial region suggests that translocation and storage of a component of the collagenous protein may occur. Environmental factors may be responsible for the triggering of matrix cycling.
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    A monoclonal antibody disrupting cell-cell adhesion of rat ascites hepatoma cells (1993)
    Springer
    Cell & tissue research 273 (1993), S. 363-370 
    Details
    ISSN: 1432-0878
    Keywords: Ascites hepatoma ; Adhesive factor ; Monoclonal antibody ; Cell membrane polarity ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract A cell surface-associated adhesive factor (AF) separated from differentiated rat ascites hepatoma AH136B cells (forming cell islands in vivo) has been highly purified by chromatography. AF is assumed to mediate the cell-cell adhesion essential to island formation of the hepatoma cells. A substance, immunologically crossreactive with AF, is present in the ascites fluid or culture medium of the AH136B cells. Because the substance is almost identical to AF in molecular weight and aggregation-promoting activity, it has been concluded that AF is released into the ascites fluid where it is concentrated. Monoclonal antibodies have been raised against AF purified from ascites fluid of AH136B cells. We have obtained a monoclonal antibody, coded MoAF-6D6, that strongly abolishes the aggregation-promoting activity of AF. When AH136B cell islands are incubated in the presence of Fab fragments of MoAF-6D6, cell detachment from the islands is evident within 24 h. Cell islands following 36-h culture show a distinct dissociation and islands completely lose their organization 48 h after culture. The dissociating effect of MoAF-6D6 is neutralized by the addition of AF. These results suggest that AF plays a significant role in the maintenance of cell islands.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00312839
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