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  • 1985-1989  (14,308)
  • 1980-1984  (9,365)
  • Life and Medical Sciences  (13,208)
  • Analytical Chemistry and Spectroscopy  (10,154)
  • Gas chromatography
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Year
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Archives of toxicology 63 (1989), S. 107-111 
    ISSN: 1432-0738
    Keywords: Analysis ; Biological monitoring ; Butoxyacetic acid ; Ethoxyacetic acid ; Gas chromatography ; Glycol ethers ; Metabolism ; Methoxyacetic acid ; Pentoxyacetic acid ; Urine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Alkoxyacetic acids are metabolically formed and excreted in urine after exposure to ethylene glycol monoalkyl ethers (alkoxyethanols) or their acetate esters. This paper presents a sensitive method based on extractive alkylation for determination of alkoxyacetic acids in urine. Alkoxyacetate ions were extracted from 200 μl urine into methylene chloride, with tetrabutylammonium acting as counter ion, and derivatized with pentafluorobenzyl bromide in a single step. After separation of the methylene chloride phase, evaporation, and dissolution of the residues in hexane the esters were analyzed by fused silica capillary column gas chromatography and electron capture detection. The esters formed were stable for at least 2 weeks at room temperature. The limit of quantification was estimated to 2 μM (corresponding to an injected amount of 2 pg) for methoxyacetic (MAA) and ethoxyacetic acid (EAA) in urine. The corresponding values for butoxyacetic acid (BAA) were 4 μM and 5 pg, respectively. The detector response was linear up to 80 μM and the formation of derivative at least up to 1 mM. The method error may be reduced by using a second alkoxyacetic acid derivative, EAA, BAA or 2-pentoxyacetic acid (PAA), as an internal standard. The sensitivity, stability, reduced number of extractions, and small volumes of reagents and sample needed make the present method useful in biomonitoring of occupational exposure to ethylene glycol ethers.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    International archives of occupational and environmental health 61 (1989), S. 249-254 
    ISSN: 1432-1246
    Keywords: Ethylene glycol ethers ; Alkoxyacetic acids ; Pentafluorobenzylbromide ; Gas chromatography ; Urine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A sensitive and specific method for the determination in urine of alkoxyacetic acids, the metabolites of ethylene glycol monoalkyl ethers, was developed by combining the advantages of two previously described methods. The acids were determined gas chromatographically as their pentafluorobenzylesters. The alkylation with pentafluorobenzylbromide was performed after dissolving the dry residue of lyophilized urine in methanol. Quantitative derivatization was obtained when the urinary pH was adjusted to pH 7.0, when the reagent concentration was 5% v/v, and when the reaction mixture was heated at 90°C for 3 h. Sample clean-up was performed by adding bidistilled water and the esters were extracted with methylene chloride with high yields (95%). Alkoxyacetic acid concentrations in the range of 0.1 to 200 mg/l could be determined with an average imprecision of ± 3.5%.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1612-1112
    Keywords: Gas chromatography ; FAME fingerprinting ; Animal fats ; Transesterification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The triglycerides of animal fats from milk, meat or cheese can also be characterized by the gaschromatographic pattern of the fatty acid methylesters (FAME) after conversion by an unsophisticated transesterification procedure. Even from the FAME pattern falsifications of commercial animal fats can be revealed by the fast separation of the FAME using a standard CW 20 M (polyethyleneglycol) capillary column. Characteristic patterns of FAME originating from different animals are shown. The patterns of the FAME from different races of the same animal are very similar, so that the characterisation according to the type of animal is not disturbed.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 27 (1989), S. 596-600 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Mass spectrometry ; Azines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary We have studied the gas chromatographic behaviour of several 3-methyl-2-benzothiazolone-azines. In HPLC analysis all the unsymmetrical azines show double peaks, whereas in HRGC analysis only some of these compounds show the two peaks corresponding to the Z (syn) and E (anti) isomers. By means GC/MS analysis the mass spectrum of each azine was recorded. We have assigned the E and Z configurations to the first and second gas chromtographic peaks on the basis of the ratio between the relative abundances of the two most significant framment ions at m/z 163 and 164.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 27 (1989), S. 221-224 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Large volume sample injection ; Closed on-column injector
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new simplified version of a “closed” on-column injector is introduced. Because of its design isobaric injection conditions do not have to be followed and a wide range of injection temperatures above the boiling point of the sample solvent can be chosen for on-column injections in capillary gas chromatography. Also, when following certain basic injection rules, injections of large sample volumes (≥20 μl or more) give accurate and reproducible results without further problems.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 28 (1989), S. 139-142 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Silica surface ; Silanols ; Strongly interacting sites
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The paper describes how the method of gas-phase titration of the strongest adsorption sites can be utilized to calculate a relative strength of interaction of the sites with chromatographic solutes. An excellent correlation with earlier, theoretical predictions of Giddings is noted. Significant influence of the sites on the width of a chromatographic band is observed when the interactions are an order of magnitude stronger than those of normal sites.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 28 (1989), S. 167-169 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Determination of monomer in polymers ; Sealed glass capillary sampling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Residual styrene in polystyrene and free phenol in phenolic plywood adhesive have been determined by sealing samples in glass capillary tubes. To prevent loss of sample the ends of the capillary tubes were sealed with a kind of putty made of anhydrous calcium sulfare, calcium carbonate and a small quantity of phenylmethylsilicone fluid. No volatile compounds were released from this sealing material when the capillary tubes were placed in a quartz vaporising furnace at temperatures up to 300°C.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 28 (1989), S. 237-240 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Slope of log plot ; Homologous series ; Retention index ; Retention time ; Uncertainty ; Free energy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The free energy of partition of a methylene group $$\Delta G_{CH_2 }^ \circ $$ is constant within a homologous series down to C5 and nearly constant to C3, contrary to the finding of Golovnya and Grigoryeva [5]. Retention indices are linear with carbon number: values may be extrapolated from higher carbon numbers to C5 within experimental uncertainty, to C4 with error no greater than 5 units and to C3 with error no greater than 10 units. Error in extrapolating the logarithm of the adjusted retention time, log t′R, to C5 is thus negligible, to C4 has possible error up to 5b/100 and to C3 up to 10b/100, whereb is the slope of the plot of log t′R against carbon number.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Optimization of gas-solid separations ; Plate height equation ; Computer mapping procedure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This paper proposes an optimization model for gas-solid chromatographic separations in a non-linear programming form and an approximate equation of the plate height for the model. A computer-modified mapping procedure is also described for searching the optimum separation conditions. Just five experiments and about 20 minutes of the computer time are needed to establish the optima of column temperature and of the carrier gas linear velocity. The relative deviation between the predicted and the experimental values was found to be within 20% for the plate heights, and within 1.5% for the retention times.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 27 (1989), S. 37-43 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Methylbromide ; Charcoal tubes ; Pollution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Air sampling of methylbromide using 900 mg HBr-treated activated charcoal tubes, followed by solvent desorption and FID or ECD chromatographic analysis, makes it possible to evaluate concentrations ranging from 0.2 ppm (1 mg×m−3) to 250 ppm (1g×m−3) at ambient temperature even with a high hygrometric level. Thermal desorption does not lead to satisfactory results.
    Type of Medium: Electronic Resource
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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 27 (1989), S. 60-66 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Mass loadability ; Stationary phase capacity ; Capillary columns
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In GLC the mass load can be normalized with respect to the amount of stationary phase in one plate. This quantity can be used for a specified solute-liquid phase combination in any capillary or packed column, irrespective of the column dimensions or the number of plates. For each individual solute in a given stationary phase a unique factor β″ can be found, which accounts for the specific shape of the isotherm of this particular combination. this factor β″ corresponds well with the activity coefficients of the solutes in the stationary phase, by which a fairly good approximation of the mass loadability of the column at hand can be made without need for experiment.
    Type of Medium: Electronic Resource
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  • 12
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 27 (1989), S. 552-558 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Radio gas chromatography ; 3H- and14C-labelled compounds ; Isotope effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Radio gas chromatography (RGC) is a valuable tool for the analysis of radioactively labelled compounds. Recent advances in capillary GC, especially in column technology and instrumentation have also induced new possibilities in this field. With regard to the preservation of the achieved separation efficiency, radioactivity detection is the main problem in capillary RGC. Based on published data and on our extensive experience in conventional RGC, a simple, reliable and versatile method has been developed for the radioactive detection: purge gas is added to the effluent of the capillary column and the RGC detection unit with conversion tube and flow-through proportional counter is used maintaining small dead volumes and dimensions. The influence of the extra-column volumes and of the total gas flow rate (of the carrier, purge and quenching gases) on the peak shape was investigated. It was also found that the isotopic effect commonly known in GC of2H- and3H-labelled compounds is hardly measurable for larger [G-14C] labelled species such as [G-14C] labelled higher fatty acids with high isotopic abundance of14C, even on the highly efficient capillary columns. The quantitative aspects of the detection method used are discussed and some applications to the analysis of labelled biochemicals (amino and fatty acids) are demonstrated.
    Type of Medium: Electronic Resource
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  • 13
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Coke oven gas evolution ; On-line gas analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A gas chromatograph will thermal conductivity detector (TCD) connected on line via a cleaning train to the semi-industrial scale Coke Oven Text Plant of the Spanish National Coal Institute (INCAR), has been used to control the evolution of the permanent gases during the coking process. The undesirable presence of oxygen in the coke oven gas can be detected with this system that will be applied to determine the end of the coking process by quantitative analysis of the gas evolved.
    Type of Medium: Electronic Resource
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  • 14
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Microwave plasma detector ; Thiophenes ; Shale oil distillates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A series of alkylthiophenes and dimethyl disulfide were tentatively identified in an oil shale retort gas condensate from a 6-kg bench-scale retort using gas chromatography with a microwave-induced helium plasma detector (GC-MIP). The sulfur species were present in concentrations ranging from 1.5 to 10.7 mol ppm in the undiluted offgas. The GC-MIP technique was successful in selectively detecting the sulfur components in the complex mixture. Quantitation was simplified relative to GC with flame-photometric detection because of the absence of quenching or other interference problems at the concentrations studied. Attempts to determine stoichiometry of the sulfur components by comparison of carbon, hydrogen, and sulfur ratios with those of standards were unsuccessful because of the complexity of the carbon and hydrogen chromatograms.
    Type of Medium: Electronic Resource
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  • 15
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Air pollutants ; Adsorbent enrichment ; Thermal desorption
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new automatic method is described for quantitative determination of some light C2–C4 hydrocarbons in urban air: ethene, ethyne, propane, propene, butane and iso-butane. This method is based on an enrichment step at room temperature using a solid sorbent and subsequent thermal desorption for gas chromatographic separation and FID detection. The instrument is built up of a small commercial gas chromatograph and a laboratory-made trap and desorption unit. The sampling parameters, sample volume, concentration and humidity of air have been investigated.
    Type of Medium: Electronic Resource
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 27 (1989), S. 159-163 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Flame photometric detector ; Sulfur compounds ; Response quenching
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The long time retardation of the main hydrocarbon peak in the chimney of the flame photometric detector greatly reduces the responses of later-eluting sulfur compounds. In the absence of hydrocarbons in the flame, the slope (s) of the log I vs. log [S] plot (where I is the sulfur response and [S] is the sulfur concentration in the sample) is of the highest value and is constant for all experimental conditions tested. Flame hydrocarbons cause the s value to decrease, and this is dependent on the oxygen to hydrogen ratio in the flame (O/H) and, under certain conditions, also on the sulfur to carbon ratio (S/C) of the sample. The abnormalities observed in the determination of methyl thiol in natural gas are explained on the basis of the present study.
    Type of Medium: Electronic Resource
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  • 17
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 27 (1989), S. 631-632 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Wide-bore glass capillary columns ; End-sealing ; Static coating
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An end-sealing method to be used for static coating of wide-bore glass capillaries is described. After the capillary was completely filled with the coating solution, one end is connected to a gas-tight syringe (10-ml volume) via silicone tubing and the other end is fixed with shortcutted silicone tubing for sealing with a plug. The method is highly successful.
    Type of Medium: Electronic Resource
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  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 27 (1989), S. 233-237 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; FTIR ; Hemoglobin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The use of N, O (S)-tert.-Butyldimethylsilyl derivatives of amino acids for capillary gas chromatography and FTIR identification of amino acids is described. Rapid identification is achieved by computerised comparison of FTIR spectra. Derivatives that are characterised by identical sets of ions in gas chromatography-mass spectrometry experiments are clearly distinguished and identified by means of their infrared spectra. This, for example, is the case with alanine, β-alanine and sarcosine, which norvaline and valine, and with norleucine, leucine and isoleucine. Unknows are also promptly detected. This is especially useful in screening biological samples for less common amino acids. Screening of hemoglogin hydrolysates for amino acid adducts is exemplified.
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  • 19
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Ethyl carbamate ; Direct injection quantification ; Cold injection system ; Optimised SIM
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An integrated procedure is described which allows direct injection quantitative screening to single figure parts per billion (μg/L) levels of ethyl carbamate in the natural matrix of distilled alcoholic beverage. Injection and detection performance was studied and optimized to allow this routine, reproducible, trace analysis without any sample pre-treatment. All aspects of the analysis including autosampler run sequences and automated internal standard report generation are initiated and controlled from a single GC/MS workstation.
    Type of Medium: Electronic Resource
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  • 20
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Trichloroethyl ester ; Dicarboxylic acid ; Urine samples ; Electron capture ; Biological monitoring
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Dicarboxylic acids were esterified by 2,2,2-trichloroethanol by using trifluoroacetic anhydride and phosphoric acid as catalysts. The method was developed to facilitate the evaluation of workers' exposure to sensitising acid anhydrides and other compounds metabolised to acids in the body. The sensitivity of the acid determination in urine was in the order of 2–4 ng ml−1 for aliphatic and alicyclic acids and 15ng ml−1 for phthalic acid.
    Type of Medium: Electronic Resource
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  • 21
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 27 (1989), S. 499-508 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Electron capture detector ; Space-charge model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Mathematical analysis, allowing the determination of the distribution of the electron and positive ion concentration in an electron-capture detector with a cylindrical electrode arrangement and with constant and pulsed voltage supplies, has been carried out. The measurements obtained confirm the assumptions concerning the “space change” model of the ECD introduced by Gobby et al. and cast doubt upon the general assumption of the complete removal of the electrons from the detector by the voltage pulse. The physical factors influencing the current characteristics of the detector and the possible distortions connected with the electrode geometry have been explained on the basis of the measurements carried out.
    Type of Medium: Electronic Resource
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  • 22
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 27 (1989), S. 455-460 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Surface free energy ; Silane-covered materials ; Film pressure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The surface free energy, or film pressure, π0, is measured for mica (Mica HK), silane-covered mica (Mica NP), Chromosorb W DMCS and glass beads. The film pressure is obtained from gas chromatography. The materials are used as adsorbents and benzyl alcohol and n-dodecane are used as molecular probes. Adsorption isotherms at 353 K are obtained from gas chromatography data and the surface free energy is computed with the help of the Gibbs equation. Values of π0 for a given surface are found to vary with the molecular probe. With benzyl alcohol π0 varies from 44 erg/cm2 for Mica 60 HK to 76 erg/cm2 for glass. In the case of n-dodecane π0 is found to vary in the same manner but the values range from 25 to 45 erg/cm2. The results are in good agreement with the values obtained with the contact angle method.
    Type of Medium: Electronic Resource
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  • 23
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 27 (1989), S. 469-471 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Headspace analysis ; Ethylene oxide ; Capillary column
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A headspace gas chromatographic method for determination of traces of ethylene oxide (EO) in sterilized materials has been developed. The method allows the determination of the amount of EO by putting the samples directly into acetonitrile and analysing by means of headspace GC. The procedure described is simple, sensitive, reproducible and linear. The lower limit of detection is 0.015 μg/g of sterilized material.
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  • 24
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Colloidal stationary phases ; Liquid crystals as stationary phases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Colloid systems consisting of the nematic liquid crystals p,p′-azoxyphenetol and p,p′-methoxyethoxyazoxybenzene and high-disperse mineral particles (aerosil, carbon black) are proposed to be used as stationary phases in gas chromatography. The dependence of the retention of normal paraffins, Rohrschneider and McReynolds test solutes (benzene, ethanol, methyl ethyl ketone, nitromethane, pyridine, butanol-1, 2-pentanone, and nitropropane) on the composition of the colloid systems was investigated. The investigated colloid sorbents including liquid crystals retain their selectivity for meta/para isomers up to 50% of the aerosil content and practically at all studied carbon black concentrations.
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  • 25
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 28 (1989), S. 24-26 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Anesthetics ; Pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A sensitive capillary gas chromatographic method is described for the simultaneous determination of lidocaine, tetracaine, procaine and dibucaine. The method was applied to the determination of anesthetics in tissue homogenates incubated at 38°C at doses between 10 and 400 mg/kg. In the liver tissue thein vitro metabolization of the studied anesthetics is most rapid for tetracaine, also fast for procaine, while for lidocaine and dibucaine the metabolization is very slow. In brain tissue thein vitro metabolization of anesthetics is very slow. The method shows good analytical parameters: linearity between 5 and 40 μg/ml; day-to-day reproducibility ca. 8% for a concentration of 20 μg/ml, precision ca. 7% for a concentration of 20μg/ml. Accuracy is also very good.
    Type of Medium: Electronic Resource
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  • 26
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Chlorinated methanes ; Activated charcoal sampling ; Pollution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A sampling method using activated charcoal, followed by percolation with ethanol and FID or ECD chromatographic analysis, depending on the concentrations to be monitored, makes it possible to evaluate concentrations of methylene chloride between 5 and 1000mg m−3, chloroform between 0.1 and 2000mg m−3, and carbon tetrachloride between 0.015 and 1000mg m−3.
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  • 27
    ISSN: 1612-1112
    Keywords: Gas chromatography ; GC/MS and headspace GC ; Elastomeric stoppers for injectables ; Trace hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Elastomeric stoppers for injectables have been surveyed by means of GC/MS screening. Residual contamination by hexanes (2-methylpentane, 3-methylpentane, n-hexane, methylcyclopentane, cyclohexane) toluene and xylenes occurred in all the samples tested. A headspace GC purity test is suggested, by using these residual chemicals as purity indexes.
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  • 28
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 28 (1989), S. 313-314 
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Fused-silica columns ; Static coating ; Sealing method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In this paper a new sealing method for the static coating of capillary columns is described. When one end of the fully filled capillary was immersed into liquid nitrogen in a Dewar flask, the coating solution at this end would be frozen and became a temporary seal, and an air-free solvent/seal interface was obtained. No bumping has ever been found at the interface, even when butane was used as solvent. By applying this sealing method, several capillary columns, including some narrow bore capillary, had been successfully coated.
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  • 29
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Renewal theory ; Monte-Carlo simulation ; Prediction of retention and peak widths
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new method for prediction of gas chromatographic retention times and peak half widths is based on the renewal theory. The only requirements are the heats of vaporization of the compounds to be separated and one calibration measurement. With this data, retention times and peak half widths can be predicted for isothermal as well as temperature-programmed gas chromatography. For the separation of non-polar substances on non-polar stationary phases the prediction error for retention times is approx. 1–2%. First simulations of polar molecules and polar stationary phases indicate that this method is also applicable in these cases but some extension will be required.
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  • 30
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 12 (1989) 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
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  • 31
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 12 (1989), S. 78-89 
    ISSN: 0886-1544
    Keywords: mitosis ; actin and myosin ; agar-overlay method ; immunofluorescence ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Synchronized cultures of Dictyostelium discoideum were used to study organizational changes of the cytoskeleton during mitotic cell division. The agar-overlay technique (Yumura et al.: J. Cell Biol. 99:894-899, 1984) was employed for immunofluorescence localization and video microscopic observation of living mitotic cells. The mitotic phase was defined by changes in chromosome configuration by using a double stain with the fluorescent dye DAPI.This study showed that the actin- and myosin-containing cytoskeleton was reversibly redistributed between the cortical ectoplasm and the endoplasm during prophase and telophase. Both actin and myosin filaments were dissociated from the cell cortex in prophase. Most of the actin and myosin was filamentous and remained in the endoplasm until telophase. Saltatory movements of organelles stopped suddenly, coincident with the breakdown of the cytoplasmic microtubule network. This change in the microtubule system was temporally coupled with the disappearance of actomyosin from the cortex. At the same time, the local vibrating movement of particles almost stopped, suggesting that the viscoelastic nature of the endoplasm was altered. In the late anaphase, actin and myosin relocalized to the cortical ectoplasm. Early in this phase, myosin filaments were localized specifically at the anticipated cleavage furrow region of the cleavage furrow, whereas actin filaments were redistributed more uniformly in the cell cortex, with an extremely large accumulation in the polar pseudopods. Subsequently the actin formed an orderly parallel array of cables along with myosin filaments in the contractile ring.The spatial segregation of actin and myosin in late anaphase was clearly demonstrated by multipolar cell division of artificially induced giant cells. Actin was relocalized in both the polar and the proximal constricting regions whereas myosin was only localized in the center of each pair of daughter microtubule networks where the cleavage furrow was formed. This study demonstrates that actin and myosin are reorganized by a temporally coordinated but spatially different mechanism during cytokinesis of Dictyostelium.
    Additional Material: 7 Ill.
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  • 32
    Electronic Resource
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    Cell Motility and the Cytoskeleton 12 (1989), S. 90-103 
    ISSN: 0886-1544
    Keywords: mitosis ; spindles ; microtubule-organizing centers ; antiphosphoprotein antibodies ; phosphorylation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Protein phosphorylation during development of sea urchin eggs from fertilization to first cleavage was examined by labeling cells with specific antiphosphoprotein antibodies. Indirect immunofluorescence staining with monoclonal antithiophos-phoprotein antibody (Gerhart et al.: Cytobios 43:335-347, 1985) has revealed that nuclei as well as centrosomes, kinetochores, and midbodies were specifically thiophosphorylated in developing eggs incubated with adenosine 5′-O (3-thiotriphosphate) (ATP-γ-S). The phosphorylation reaction required Mg2+ but was not dependent on cAMP or calmodulin in detergent-extracted models. Centrosomes were purified by fractionation of isolated mitotic spindles with 0.5 M KCl extraction. The thiophosphoproteins were retained in the purified centrosomes and the antibody recognized a major 225-Kd polypeptide on immunoblots. In an independent preparation, a monoclonal antiphosphoprotein antibody (CHO3) was found also to react with mitotic poles and stained a 225-Kd polypeptide, confirming the centrosome specificity of this protein. Immunoelectron microscopy showed that the 225-Kd thiophosphoprotein was found at mitotic poles associated with granules to which mitotic microtubules were directly attached. Unlike centrosomes in permeabilized eggs, those in isolated spindles could not be thiophosphorylated, possibly due to inactivation or loss of either phosphorylation enzymes or cofactors, or both, during isolation. The immunofluorescence labeling of thiophosphate could be inhibited by ATP and AMP-PNP in a concentration-dependent manner. Exogenous ATP could abolish thiophosphate-staining more effectively when added with phosphatase inhibitors, suggesting a dynamic state in which centrosomal proteins are being phosphorylated and dephosphorylated in rapid succession by the action of protein kinase(s) and phosphatase(s).
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  • 33
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    Cell Motility and the Cytoskeleton 13 (1989), S. 212-220 
    ISSN: 0886-1544
    Keywords: meiosis ; live observation ; oscillatory movements ; microtubule assembly-disassembly ; spindle forces ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Chromosome movements in Mesostoma ehrenbergii spermatocytes were studied using conventional video light microscopy. Kinetochore regions of the three bipolarly oriented bivalents displayed periodic back and forth movements directed to both poles at metaphase I, leading to periodic lenght changes of the bivalents. Velocity was 8-10 μm/min (maximum 17 μ/min), about one order of magnitude higher than the normal meiotic or mitotic chromosome movements of other species. One cycle of movement lasted for about 100 seconds. The movement of kinetochore regions implies that the antagonistic chromosome fibres periodically grow (assemble) and shorten (disassemble) at comparable rates. Poleward movements must be caused by forces generated in disassembling fibres, whereas movements away from the poles, accompanied by fibre growth, are probably brought about by the internal elastic force of the chromosomes. Antagonistic fibres of a bivalent can operate in or out of phase. The movements of the three kinetochore regions are coordinated insofar as growing and shortening fibres coexist in a half-spindle at almost any time [Fuge, H. (1987): European Journal of Cell Biology 44:294-298]. These observations are discussed in terms of microtubule dynamics.
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  • 34
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    Cell Motility and the Cytoskeleton 13 (1989), S. 239-244 
    ISSN: 0886-1544
    Keywords: sperm ; nucleotide analog ; kinetics ; Stronglyocentrotus purpuratus ; reactivation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The 2-substituted ATP analog 2-Chloro ATP was tested for its capacity to support axonemal movement. The movement of sea urchin axonemes reactivated with 2-CI ATP appeared very similar to that with ATP. Detailed waveform analysis indicated that bend angle and shear amplitude were not significantly different for ATP and 2-CI ATP. Although wavelength differs at particular nucleotide concentrations, if normalized to the beat frequency, it is similar for ATP and 2-CI ATP. The main difference in the movement with the two analogs was seen in beat frequency and sliding velocity. The Vmax for beat frequency and mean sliding velocity was lower for 2-CI ATP. The apparent Km for beat frequency and sliding velocity was much lower for 2-CI ATP. The ratio of these two effects, that is, (Vmax/Km) is higher for 2-CI ATP. Thus 2-CI ATP is a good substrate for axonemal movement. The significantly lower Km of 2-CI ATP was also demonstrated by its ability to support oscillatory motion at concentrations below that for ATP. The observations identify the structures and conformation of substrate necessary to support axonemal movement.
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  • 35
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    Cell Motility and the Cytoskeleton 12 (1989), S. 53-65 
    ISSN: 0886-1544
    Keywords: reversible binding ; computer simulation ; transport rates ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A model for slow axonal transport is developed in which the essential features are reversible binding of cytoskeletal elements and of soluble cytosolic proteins to each other and to motile elements such as actin microfilaments. Computer simulation of the equations of the model demonstrate that the model can account for many of the features of the SCa and SCb waves observed in pulse experiments. The model also provides a unified explanation for the increase and decrease of neurofilament transport rates observed in various toxicant-induced neuropathies.
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  • 36
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    Cell Motility and the Cytoskeleton 12 (1989), S. 113-122 
    ISSN: 0886-1544
    Keywords: mitosis ; spindle ; kinetochore ; centrosome ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: To investigate the association of calmodulin (CaM) with microtubules (MTs) in the mitotic apparatus (MA), the distributions of CaM and tubulin were examined in cells in which the normal spindle organization had been altered. A fluorescent CaM conjugate with tetramethylrhodamine isothiocyanate (CaM-TRITC) and a dichlorotriazinyl aminofluorescein conjugate with tubulin (tubulin-DTAF) were injected into cells that had been treated with the MT inhibitor nocodazole. With moderate nocodazole concentration (0.3 μg/ml, 37°C, 4 h) in live cells, CaM-TRITC and tubulin-DTAF concentrated identically on or near the centrosomes and kinetochores. In serial sections of these cells, small MT segments were observed by transmission electron microscopy (TEM) in the regions where fluorescent protein had concentrated. When a higher drug concentration was used (3.0 μg/ml, 37°C, 4 h), no regions of CaM-TRITC or tubulin-DTAF localization were observed, and no MTs were observed when serial sections were examined by TEM. However, following release from the high-concentration nocodazole block, CaM-TRITC colocalized with newly formed MTs at the kinetochores and centrosomes. Later in the recovery period, when chromosome-to-pole fibers had formed, CaM association with kinetochores diminished, ultimately attaining its normal pole-proximal association with kinetochore MTs in cells that progressed through mitosis. We interpret these observations as supporting the hypothesis that in the MA, CaM attains a physical association with kinetochore MTs and suggest that CaM-associated MTs may be inherently more stable.
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  • 37
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    Cell Motility and the Cytoskeleton 12 (1989), S. 157-168 
    ISSN: 0886-1544
    Keywords: axolotl ; cell differentiation ; cell shape ; cytoskeleton ; nucleated erythrocyte ; microtubule ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The spleen of Ambystoma mexicanum (axolotl) larvae develops as a closed sac containing differentiating nucleated erythrocytes, and is typically isolated from the general circulation for about 10 days post-hatching. Beginning 3-4 days posthatching, it can be removed intact for examination of the morphology and cytoskeletal structure of the erythropoietic cells. In the smallest (earliest) spleens, spheroidal cells predominate, while older ones contain a preponderance of cells exhibiting the flattened elliptical morphology typical of all non-mammalian vertebrate erythrocytes. Most striking in the splenic erythroid population are cells with singly or doubly pointed morphology. Though common in the developing spleen and circulation of young larvae, pointed cells are less frequently encountered in the circulation of older larvae, indicating that they are intermediate stages in the differentiation of spheroids to flattened ellipsoids. This is supported by structural observations on cytoskeletons prepared from the splenic cells. Incomplete singly and doubly pointed marginal bands of microtubules are observed, many of which contain a pair of centrioles within or close to a pointed end, suggestive of organizing center function. The observations are consistent with a sequence of changes in cell morphology from spherical to doubly pointed to singly pointed to flattened ellipse, causally linked to stages of marginal band biogenesis.
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  • 38
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    Cell Motility and the Cytoskeleton 12 (1989), S. 185-194 
    ISSN: 0886-1544
    Keywords: myofibril assembly ; focal contacts ; vinculin ; α-actinin ; connectin ; immunocytochemistry ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The relationship of nascent myofibrils with the accumulation of adhesion plaque proteins and the formation of focal cell contacts was studied in embryonic chick cardiac myocytes in vitro. The cultures were double-stained with various combinations of the specific antiactin drug phalloidin and antibodies against vinculin, α-actinin, connectin (titin), myosin heavy chain, fibronectin, and desmin and examined under fluorescence and interference reflection microscopy.In the areas of myofibril assembly, vinculin and α-actinin plaques were formed at the ventral sarcolemmae. These areas overlapped with the sites of cell-to-substrate focal contacts and extracellular fibronectin. Because the myofibrils always ran in a straight line between these sites, polarized lines appeared to be generated within the cells in response to their physical (e.g., stress) and/or biochemical environment (e.g., adhesion plaque proteins). The possible presence of other factors cannot be ruled out for the proper alignment of myofibrils. As soon as myofibrils came to span between these adhesion sites, they exhibited typically mature cross-striated characteristics. Thus, the formation of these inferred lines has some relation to or is in fact necessary for the maturation of myofibrils, in addition to the directional arrangement of sarcomeric proteins.Additionally, synthesis and distribution of myosin and connectin were tightly linked during early developmental (premyofibril and myofibril) stages. The spatial deployment of desmin was not coupled with vinculin. Thus, connectin and desmin do not appear to form the initial scaffold of sarcomeres.
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  • 39
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    Cell Motility and the Cytoskeleton 12 (1989), S. 283-283 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 40
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    Cell Motility and the Cytoskeleton 12 (1989), S. 273-282 
    ISSN: 0886-1544
    Keywords: cytoskeleton ; microtubules ; axons ; sensory neurons ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The comparative distribution of tyrosinated, detyrosinated, and acetylated α-tubulins was examined in neurites of rat dorsal root ganglion neurones in culture using immunofluorescence microscopy. Phase contrast observations of single neurones revealed that the neurites were actively motile, and rhodamine phalloidin staining of actin filaments showed the extent of lamellopodia and microspike projections from the growth cones. From double-labelling experiments using antibodies against tyrosinated, detryrosinated, or acetylated α-tubulin, it was found that the three different isoforms were differentially localised in neurites and growth cones. Detyrosinated and acetylated forms of α-tubulin were in the main restricted to the neurites extending no further than the base of the growth cones. Tyrosinated α-tubulin was, however, distributed throughout the body of the growth cone and into the base of some microspikes. Following treatment with taxol to promote microtubule assembly, detyrosinated and acetylated α-tubulins were found to be colocalised with tyrosinated α-tubulins throughout the growth cones of all cells examined. These results would be consistent with axonal transport of tyrosinated α-tubulin followed by assembly in the growth cone and subsequent detyrosination and acetylation. In addition the presence of unmodified α-tubulin in the growth cone may be necessary for the provision of labile microtubules for growth cone motility and extension.
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  • 41
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    Cell Motility and the Cytoskeleton 13 (1989), S. 158-169 
    ISSN: 0886-1544
    Keywords: chemotaxis ; cAMP ; cytoskeleton ; ameba ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The distribution of myosin was studied in amebae of the Ax-3 and NC-4 strains of Dictyostelium migrating at room temperature, using indirect immunofluorescence of aggregation-competent amebae and the agar-overlay technique. Amebae were fixed in methanol-formaldehyde or absolute acetone at -15°C before or after stimulation with micromolar cyclic AMP at room temperature (20-25°C). Myosin was detected by monoclonal antibodies to Dictyostelium myosin heavy chain followed by a fluorescent secondary antibody that had been preabsorbed to remove nonspecific staining. In both strains there was a striking increase in intensity of anti-myosin immunofluorescence in the cortex where it appeared as a continuous ring 30 seconds after addition of cyclic AMP. This correlated with a rounding up of the cell body. Sixty seconds after stimulation there was a clear reduction of cytoplasmic myosin rods in conjunction with the increased cortical localization. At this time extensions of largely hyaline cytoplasm were observed that extended beyond the cortical shell of myosin. Two minutes after the stimulus the immunofluorescence remained as a distinct line at the cortex, but the cells began to resume in elongated shape. By 3 minutes (NC-4 strain) or 5 minutes (Ax-3 strain) the amebae had largely returned to the control shape, and myosin had returned to its control distribution. Counts of the treated cells at different time points substantiated the observations of individual cells. The time course of translocation of myosin in the Ax-3 strain parallels the time course of myosin phosphorylation reported in previous studies. The results are interpreted in terms of a working hypothesis for the mechanism of translocation.
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  • 42
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    Cell Motility and the Cytoskeleton 13 (1989), S. 225-238 
    ISSN: 0886-1544
    Keywords: centrosome ; DAPI ; immunofluorescence ; immunoperoxidase ; microtubules ; mitosis ; scleroderma serum ; tubulin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Double-label immunofluorescence of tubulin and preicentriolar material (PCM) was carried out with mitotic nuclei in the coenocytic green alga Ernodesmis. Spindle poles are heavily labeled with serum 5051 (anti-PCM) from midprophase through mid- to late anaphase, and bright fluorescence is also evident at the tips of the elongated interzonal spindle in telophase nuclei. Very faint labeling with anti-PCM is also detected throughout the spindle (and/or its matrix) at all mitotic stages. Control treatments demonstrated that nonspecific surface labeling of chloroplasts with anti-PCM may be due to some naturally occurring component of human sera rather than to specific labeling by the anti-PCM serum. Ultrastructural work indicates that the centrosome is always associated with spindle poles through anaphase, but not with the tips of the interzonal telophase Immunoper-oxidase electron microscopy verifies that anti-PCM labels the centrosomes of mitotic nuclei in these cells. However, labeling is also present inside the presistent nuclear envelope at the spindle poles, during metaphase, anaphase, and at the tips of the interzonal spindles. Regions of heaviest labeling correspond with amorphous material near the centrioles and at the spindle poles, as evident in conventional electron microscope preparations. The origin of intranuclear amorphous material that labels with anti-PCM is unclear, but the ends of many spindle microtubules are embedded in it, especially at anaphase, and the tips of microtubules near the amorphous material are often labeled with the antiserum. These results indicate for the first time that serum 5051 does indeed label PCM at the poles of centric spindles in plant cells. Although the location of the labeled material suggests it is associated with the nucleation of spindle microtubules, this conclusion requires more information about microtubule dynamics in these cells. Caution is also warranted in interpreting variant anti-PCM labeling patterns in other plant cells because of spurious labeling of the spindle itself and other cytoplasmic organelles.
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  • 43
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 44
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    Cell Motility and the Cytoskeleton 14 (1989), S. 92-102 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 45
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    Cell Motility and the Cytoskeleton 14 (1989), S. 163-168 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 46
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    Cell Motility and the Cytoskeleton 14 (1989) 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 47
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    Cell Motility and the Cytoskeleton 14 (1989), S. 177-177 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 48
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    Cell Motility and the Cytoskeleton 14 (1989), S. 178-182 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 49
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    Cell Motility and the Cytoskeleton 14 (1989), S. 183-186 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 50
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    Cell Motility and the Cytoskeleton 14 (1989), S. 187-193 
    ISSN: 0886-1544
    Keywords: centrosphere ; locomotion ; MTOC ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We have previously shown that BHK syncytia have the ability to locomote provided the centrospheres are clustered and located adjacent to the cluster of nuclei. This article reports that experimental reorganizations of the centrospheres or the nuclei change the motile behavior of BHK syncytia in a way that is consistent with our previous observations: When fusion of the multiple nuclei occurred in stationary syncytia whose multiple nuclei encircled the centrosphere cluster, the centrospheres were expelled from the ring of nuclei. Consequently, locomotion was initiated in these syncytia even if they had been previously stationary for up to 5 days. Conversely, when a 2-hour incubation in 5 μg/ml cytocholasin B caused the cluster of nuclei to surround the centrosphere cluster, the locomotion of the syncytia was inhibited. Similarly, the dispersal of the centrosphere cluster induced by a 4-hour incubation in 1 μg/ml of colcemid resulted in the long-term cessation of locomotion in motile syncytia.
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  • 51
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    Cell Motility and the Cytoskeleton 14 (1989), S. 201-219 
    ISSN: 0886-1544
    Keywords: cytokinesis ; microinjection ; cleavage furrow ; mitosis ; midbody ; stress fibers ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Actin and the light chains of myosin were labeled with fluorescent dyes and injected into interphase PtK2 cells in order to study the changes in distribution of actin and myosin that occurred when the injected cells subsequently entered mitosis and divided. The first changes occurred when stress fibers in prophase cells began to disassemble. During this process, which began in the center of the cell, individual fibers shortened, and in a few fibers, adjacent bands of fluorescent myosin could be seen to move closer together. In most cells, stress fiber disassembly was complete by metaphase, resulting in a diffuse distribution of the fluorescent proteins throughout the cytoplasm with the greatest concentration present in the mitotic spindle. The first evidence of actin and myosin concentration in a cleavage ring occurred at late anaphase, just before furrowing could be detected. Initially, the intensity of fluorescence and the width of the fluorescent ring increased as the ring constricted. In cells with asymmetrically positioned mitotic spindles, both protein concentration and furrowing were first evident in the cortical regions closest to the equator of the mitotic spindle. As cytokinesis progressed in such asymmetrically dividing cells, fluorescent actin and myosin appeared at the opposite side of the cell just before furrowing activity could be seen there. At the end of cytokinesis, myosin and actin were concentrated beneath the membrane of the midbody and subsequently became organized in two rings at either end of the midbody.
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  • 52
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    Cell Motility and the Cytoskeleton 12 (1989), S. 33-41 
    ISSN: 0886-1544
    Keywords: phosphorylation ; MPM-2 ; mitotic spindle ; microtubule-associated protein ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Mitotic spindles isolated from the diatom Stephanopyxis turris become thiophosphorylated in the presence of ATPγS at specific locations within the mitotic apparatus, resulting in a stimulation of ATP-dependent spindle elongation in vitro. Here, using indirect immunofluorescence, we compare the staining pattern of an antibody against thiophosphorylated proteins to that of MPM-2, an antibody against mitosis-specific phosphoproteins, in isolated spindles. Both antibodies label spindle poles, kinetochores, and the midzone. Neither antibody exhibits reduced labeling in salt-extracted spindles, although prior salt extraction inhibits thiophosphorylation in ATPγS. Furthermore, both antibodies recognize a 205 kd band on immunoblots of spindle extracts. Microtubule-organizing centers and mitotic spindles label brightly with the MPM-2 antibody in intact cells. These results show that functional mitotic spindles isolated from S. turris are phosphorylated both in vivo and in vitro. We discuss the possible role of phosphorylated cytoskeletal proteins in the control of mitotic spindle function.
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  • 53
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    Cell Motility and the Cytoskeleton 12 (1989), S. 66-66 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 54
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    Cell Motility and the Cytoskeleton 12 (1989), S. 71-77 
    ISSN: 0886-1544
    Keywords: microtubule ; colchicine ; cold-treatment ; kinesin localization ; EBTr cells ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The localization of kinesin in EBTr (bovine embryonic trachea fibroblast) cells was studied by indirect immunofluorescence microscopy using an affinity-purified antibody against bovine adrenal kinesin.It has already been shown that in interphase cells a part of kinesin is located on microtubules and the rest diffusely distributed throughout the cytoplasm [Murofushi et al., 1988]. When microtubules were depolymerized with cold or colchicine treatment, antikinesin antibody-stained fibrous components distinct from microtubules. These fibrous structures were considered to be stress fibers because they were stained with rhodamine-phalloidin and because the fibrous staining with antikinesin antibody was completely lost by treating the cells with cytochalasin D along with colchicine. When cold-treated cells in which a major part of kinesin had been localized on stress fibers were incubated at 37°C, kinesin reappeared on reconstituted microtubules. These observations strongly suggest that kinesin has affinity not only to microtubules but also to stress fibers in culture cells.
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  • 55
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    Cell Motility and the Cytoskeleton 12 (1989), S. 123-123 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 56
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    Cell Motility and the Cytoskeleton 12 (1989), S. 139-149 
    ISSN: 0886-1544
    Keywords: spectrin ; hamster ; cardiac tissue ; cytoskeletal-membrane ; myofibrils ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The spectrins are a family of cytoskeletal-membrane proteins that have a wide tissue distribution. In the present study, we employed polyclonal antibodies made against mammalian and avian erythroid spectrins as well as mammalian brain spectrin to assess their presence and distributions in the mammalian heart. Western blot analyses revealed that all three antibodies were specific for a 240,000 molecular weight α-spectrin subunit found in hamster erythrocyte ghost homogenates, whole hamster heart, and isolated hamster cardiac myofibril homogenates. Spectrin staining was absent from the Triton X-100-extracted supernatant fraction of myofibril preparations, suggesting that the protein is linked to the myofibril precipitate after exposure to the detergent. Frozen, unfixed, 2-μm-thick; sections of adult, Syrian golden hamster cardiac tissue exhibited strong immunofluorescent staining of intercalated discs and Z-bands using all three antibodies. In addition, the mammalian erythroid spectrin antibodies showed staining of the sarcolemma, and in cross section, revealed a delicate internal network of staining that appears to surround individual myofibrils. This may be T-tubule-associated staining. Myofibrils isolated from cardiac myocytes using Triton X-100 show positive Z-band staining using all three antibodies. Double staining with Texas Red-labeled monoclonal desmin and FITC-labeled polyclonal spectrin antibodies revealed that both stained the myofibrillar Z-line regions. These results demonstrate that spectrin is closely associated with the membranes, myofibrils, and intermediate filaments in the mammalian heart.
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  • 57
    ISSN: 0886-1544
    Keywords: stress fibers ; fibroblasts ; myosin ; bipolar filaments ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The authors examined the molecular organization of myosin in stress fibers (microfilament bundles) of cultured mouse embryo fibroblasts. To visualize the organization of myosin filaments in these cells, fibroblast cytoskeletons were treated with gelsolin-like protein from bovine brain (hereafter called brain gelsolin), which selectively disrupts actin filaments. As shown earlier [Verkhovsky et al., 1987], this treatment did not remove myosin from the stress fibers. The actin-free cytoskeletons then were lightly sonicated to loosen the packing of the remaining stress fiber components and fixed with glutaraldehyde.Electron microscopy of platinum replicas of these preparations revealed dumbbell-shaped structures of approximately 0.28 μm in length, which were identified as bipolar myosin filaments by using antibodies to fragments of myosin molecule (subfragment I and light meromyosin) and colloidal gold label. Bipolar filaments of myosin in actin-free cytoskeletons were often organized in chains and lattices formed by end-to-end contacts of individual filaments at their head-containing regions. Therefore, after extraction of actin, it was possible for the first time to display bipolar myosin filaments in the stress fibers of cultured cells.
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  • 58
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    Cell Motility and the Cytoskeleton 12 (1989) 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 59
    ISSN: 0886-1544
    Keywords: mechanochemistry ; fast axonal transport ; cytoskeleton ; vesicle ; motor protein ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Determination of kinetic properties for kinesin adenosine triphosphatase (ATPase), a proposed motor for transport of membranous organelles, requires adequate amounts of kinesin with a consistent level of enzymatic activity. A purification procedure is detailed that produces approximately 2 mg of kinesin at up to 96% purity from 800 g of bovine brain. This protocol consists of a microtubule affinity step using 5′-adenylylimidodiphosphate (AMP-PNP); followed by gel filtration, ion exchange, and hydroxylapatite chromatography; and then sucrose density gradient centrifugation. The microtubule-activated ATPase activity of kinesin coeluted with kinesin polypeptides throughout the purification. Highly purified kinesin had a Vmax of 0.31 μmol/min/mg in the presence of microtubules, with a Km for ATP of 0.20 mM. The kinetic constants obtained in these studies compare favorably with physiological levels of ATP and microtubules. Variations in buffer conditions for the assay were found to affect ATPase activity significantly. A study of the ability of kinesin to utilize a variety of cation-ATP complexes indicated that kinesin is a microtubule-stimulated Mg-ATPase, but kinesin is able to hydrolyze Ca-ATP, Mn-ATP, and Co-ATP as well as Mg-ATP in the presence of microtubules. In the absence of microtubules, Ca-ATP appears to be the best substrate. Studies with several inhibitors of ATPases determined that vanadate inhibited kinesin ATPase at the lowest concentrations of inhibitor, but significant inhibition of the ATPase also occurred with submillimolar concentrations of AMP-PNP. Other inhibitors of kinesin include N-ethylmaleimide, adenosine diphosphate (ADP), pyrophosphate, and tripolyphosphate. Further characterization of the kinetic properties of the kinesin ATPase is important for understanding the molecular mechanisms for transport of membranous organelles along microtubules.
    Additional Material: 10 Ill.
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  • 60
    ISSN: 0886-1544
    Keywords: ABP-120 ; myosin ; actin polymerization ; amoeboid chemotaxis ; cAMP ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Triton-insoluble cytoskeletons were isolated from Dictyostelium discoideum AX3 cells prior to and following stimulation with 2′deoxy cyclic adenosine monophos-phate (cAMP). Temporal changes in the content of actin and a 120,000 dalton actin-binding protein (ABP-120) in cytoskeletons following stimulation were monitored. Both actin and ABP-120 were incorporated into the cytoskeleton at 30-40 seconds following stimulation, which is cotemporal with the onset of pseudopod extension during stimulation of amoebae with chemoattraciants. Changes in the content of total cytoskeletal protein and cytoskeletal myosin were determined under the same experimental conditions as controls. These proteins exhibited different kinetics from those of cytoskeletal ABP-120 and actin following the addition of 2′deoxy cAMP. The authors concluded that the association of ABP-120 with the cytoskeleton is regulated during cAMP signalling. Furthermore, these results indicate that ABP-120 is involved in cross-linking newly assembled actin filaments into the cytoskeleton during chemoattractant-stimulated pseudopod extension.
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  • 61
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    Cell Motility and the Cytoskeleton 13 (1989), S. 41-56 
    ISSN: 0886-1544
    Keywords: cytoskeleton ; ultrastructure ; tegument ; syncytium ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A hallmark feature of parasitic platyhelminths is a cytoarchitecturally unusual syncytial epidermis composed of a peripheral layer of continuous cytoplasm (the ectocytoplasm) connected to underlying nucleated cell bodies by small cytoplasmic bridges. The helminth epidermis, or tegument, plays important roles in protection and nutrient acquisition; cestodes, in fact, completely lack a gastrointestinal tract and absorb all nutritive material through the tegument. Perhaps not surprisingly, the cestode tegument bears certain resemblances to the mucosal epithelium of the vertebrate small intestine, including the possession of a microvillous brush border upon the surface of the ectocytoplasm. In contrast to the intestinal epithelial cell, however, very little is known concerning the nature and organization of the cytoskeleton within the helminth epidermis. Therefore, a number of different microscopical preparative techniques were used to examine the tegument of the tapeworm Hymenolepis diminuta for the presence and distribution of microfilaments, intermediate filaments, and microtubules. It was found that both actin-containing microfilaments and intermediate-sized filaments are present but are restricted to specific locations along the plasmalemmae of the ectocytoplasm. In contrast, microtubules are found throughout the tegument, and are concentrated in the supranuclear regions of the perikarya and in the cytoplasmic bridges interconnecting the perikarya and ectocytoplasm. Unlike brush borders of most other epithelia, the cestode epidermal brush border lacks a filamentous terminal web and is instead associated with microtubules. A network of fine filaments, 5-8 nm in diameter but distinct from actin-containing microfilaments, runs throughout the ectocytoplasm and appears to interlink tegumental vesicles. These fine filaments may represent the primary “skeletal” system responsible for maintaining the structure of the tegumental cytoplasm.
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  • 62
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    Cell Motility and the Cytoskeleton 13 (1989), S. 1-8 
    ISSN: 0886-1544
    Keywords: flagella ; membrane ; glycoproteins ; concanavalin A ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: As an alternative to swimming through liquid medium by the coordinated bending activity of its two flagella, Chlamydomonas can exhibit whole cell gliding motility through the interaction of its flagellar surfaces with a solid substrate. The force transduction occurring at the flagellar surface can be visualized as the saltatory movements of polystyrene microspheres. Collectively, gliding motility and polystyrene microsphere movements are referred to as flagellar surface motility. The principal concanavalin A binding, surface-exposed glycoproteins of the Chlamydomonas reinhardtii flagellar surface are a pair of glycoproteins migrating with apparent molecular weight of 350 kDa. It has been hypothesized that these glycoproteins move within the plane of the flagellar membrane during the expression of flagellar surface motility. A novel mutant cell line of Chlamydomonas (designated L-23) that exhibits increased binding of concanavalin A to the flagellar surface has been utilized in order to restrict the mobility of the concanavalin A-binding flagellar glycoproteins. Under all conditions where the lateral mobility of the flagellar concanavalin A binding glycoproteins is restricted, the cells are unable to express whole cell gliding motility or polystyrene microsphere movements. Conversely, whenever cells can redistribute their concanavalin A binding glycoproteins in the plane of the flagellar membrane, they express flagellar surface motility. Since the 350 kDa glycoproteins are the major surface-exposed flagellar proteins, it is likely that most of the signal being followed using fluorescein isothiocyanate (FITC)-concanavalin A is attributable to these high molecular weight glycoproteins. Therefore, it is likely that the 350 kDa glycoproteins are the ones that must move laterally in the plane of the flagellar membrane in order for the cell to express whole cell gliding motility and microsphere movements along the flagellar surface. This study represents one of the first demonstrations, in any cell type, that whole cell locomotion requires glycoprotein movement within the plane of the plasma membrane.
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  • 63
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    Cell Motility and the Cytoskeleton 13 (1989), S. 145-157 
    ISSN: 0886-1544
    Keywords: microtubule ; membrane ; sytoskeleton ; Trypanosomatidae ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The cytoskeleton of Crithidia fasciculata consists of a corset of paralle microtubules enclosing the cell body and closely underlying the plasma membrane. Distinct sets of crosslinks appear to connect tubules to each other and to membrane. Our objective is to determine the composition of these crosslinks and to elucidate the basis of this spectacular example of membrane-microtubule interaction. We purified three proteins (designated COP-33, -41, and -61 by their subunit Mr), which were consistently abundant in highly purified cytoskeletons. All three bound strongly to microtubules in vitro, and the first two induced bundles through periodic crosslinking. Polyclonal antibodies against each have been used to try to localize these proteins in thin sections of cells or whole mounts of cytoskeletons. Antibodies to COP-41 bound sepcifically to glycosomes, organelles that encapsulate many glycolytic enzymes in these protozoa, and COP-41 has been identified as glyceraldehyde 3-P dehydrogenase.
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  • 64
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    Cell Motility and the Cytoskeleton 13 (1989), S. 104-111 
    ISSN: 0886-1544
    Keywords: embryo ; hamster ; detergent extraction ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Mammalian eggs and embryos contain an extensive detergent-resistant cytoskeletal network, including many elements which have been referred to as sheets in hamster eggs. In this study we examined the structure of the sheet-like components by using embedment-free sections and freeze-fracture electron microscopy and found that the sheets are composed of both filamentous and particulate components. In addition, exposure to a high salt extraction medium resulted in the disappearance of the sheets at the ultrastructural level. SDS-polyacrylamide gel electrophoresis of the cell fractions revealed four stainable proteins solubilized by the high salt extraction with one of the proteins being greatly enriched. Because these cytoskeletal sheets undergo an extensive reorganization coincident with key events during early development they serve as internal markers for the establishment of polarity and subsequent differentiation of the first embryonic epithelium, the trophectoderm.
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  • 65
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    Cell Motility and the Cytoskeleton 13 (1989) 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
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  • 66
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    Cell Motility and the Cytoskeleton 13 (1989), S. 112-122 
    ISSN: 0886-1544
    Keywords: cytoskeleton ; cell adhesion ; light chain phosphorylation ; immunofluorescence microscopy ; fluorescent indicators ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Following our study in Balb/c 3T3 cells and other cultured fibroblasts of the changes in myosin light chain phosphorylation associated with alterations in cell shape, attachment, and receptor patching, we have now determined the corresponding changes in cytoskeletal myosin distribution, and in the cellular calcium concentration, since this might, in part, mediate such responses.Immunofluorescence microscopy showed that myosin assembly into ordered forms such as actomyosin bundles and myosin sheath almost always correlated with previously shown high phosphorylation levels of myosin regulatory light chain, whereas diffuse distributions usually correlated with low or undetectable levels. An exception was observed in treatment to alter cellular cAMP levels when, in a biphasic response, assembly was correlated inversely with the phosphorylation states shown previously.Fluorescent indicators for intracellular calcium concentration, [Ca++]i, showed that myosin disassembly by trypsin or EGTA acting externally on the cells was preceded by a transient increase in [Ca++]i. For EGTA this was associated with transient recruitment of myosin into dorsal sheath structure as well as the transient enhancement of phosphorylation shown earlier. Blockage of EGTA-induced disassembly could be achieved by azide, which also caused an immediate increase in [Ca++]i and inhibited its subsequent decline. Trypsin-induced dephosphorylation did not appear to involve an eventual reduction of [Ca++]i. Therefore, in many but not all of the systems studied, correlated changes were observed in myosin assembly, [Ca++]i, and the myosin phosphorylation levels shown earlier.
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  • 67
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    Cell Motility and the Cytoskeleton 13 (1989), S. 170-180 
    ISSN: 0886-1544
    Keywords: Avena ; cytoskeleton ; Gramineae ; guard cell ; microtubule ; stomatal complex ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Changes in microtubule organization were monitored in the stomatal complexes of Avena sativa using tubulin immunocytochemistry. Radial arrays of cortical microtubules, previously thought to be characteristic of guard cells, also appear in adjacent subsidiary cells early in development. The subsidiary cell arrays are evident even before guard cells form via division of precursor guard mother cells. Thus, before the stomatal pore opens between sister guard cells, each complex contains four similar microtubule arrays. As the pore opens, however, the subsidiary cell system is reorganized into a network of microtubules distributed along the length of the cell. A similar change is effected in the guard cells after the pore opens. Subsidiary cells and guard cells elongate during later stages of differentiation, and a thickened wall is deposited int he narrow midzone of the latter. At the same time, microtubules in both cells assume a more axial orientation. The results are discussed in terms of developmental symmetry and the control of microtubule organization and cell wall deposition.
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  • 68
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    Cell Motility and the Cytoskeleton 14 (1989), S. 3-11 
    ISSN: 0886-1544
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 3 Ill.
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  • 69
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    Cell Motility and the Cytoskeleton 14 (1989), S. 527-543 
    ISSN: 0886-1544
    Keywords: immunofluorescence ; video-enhanced contrast microscopy ; protrusions ; lamellipodia ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The formation of lamellipodia in migrating cells involves dynamic processes that occur in a cyclic manner as the leading edge of a cell slowly advances. We used video-enhanced contrast microscopy (VEC) to monitor the motile behavior of cells to classify protrusions into the temporal stages of initial and established protrusions (Fisher et al.: Cell Motility and the Cytoskeleton 11:235-247, 1988), and to monitor the fixation of cells. Multiple parameter fluorescence imaging methods (DeBiasio et al.: Journal of Cell Biology 105:1613-1622, 1987; Waggoner et al.: Methods in Cell Biology, Vol. 30, Part B, pp. 449-478, 1989) were then used to determine and to map accurately the distributions of actin, myosin and microtubules in specific types of protrusions. Initial protrustions exhibited no substructure as evidenced by VEC and actin was diffusely arranged, while myosin and microtubules were absent. Newly established protrusions contained diffuse actin as well as actin in microspikes. There was a delay in the appearance of myosin into established protrusions relative to the presence of actin. Microtubules were found in established protrusions after myosin was detected, and they were oriented parallel to the direction of migration. Actin and myosin were also localized in fibers transverse to the direction of migration at the base of initial and established protrusions. Image analysis was used to quantify the orientation of actin fibers relative to the leading edge of motile cells. The combined use of VEC, multiple parameter immunofluorescence, and image analysis should have a major impact on defining complex relationships within cells.
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  • 70
    ISSN: 0886-1544
    Keywords: Spermatozopsis ; flagellar roots ; rhizosyndesmos ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The cytoskeleton of the naked, biflagellate green alga Spermatozopsis similis Preisig & Melkonian was isolated by treatment of cells with Nonidet P-40 (0.1%) in lysis buffer (30 mM HEPES, 5 mM EGTA, 15 mM KCl, pH 7) and studied in detail by whole-mount electron microscopy. Isolated cytoskeletons retain the twisted shape of live cells and consist of the two axonemes, the basal apparatus with 4 microtubular and two fibrous roots, and 8-10 secondary cytoskeletal microtubules (SCMT's). The four microtubular flagellar roots differ in number of microtubules (two types with 2 or 5 microtubules, respectively), in their association with fibrous roots of the system I-type (two-stranded roots), in total length (two roots with an average of 4.5 μm and two roots with and average of 7.5 μm), and in length of individual root microtubules. Certain of the root microtubules and most of the SCMT's extend to the posterior end of the cell where they converge, terminate and are interconnected by a fibrous cap-like structure, the rhizosyndesmos. This novel structure consists of a network of 2 nm filaments that presumably lacks centrin as indicated by double immunofluorescence (anti-α-tubulin and anti-centrin) of isolated cytoskeletons. Two-dimensional gel electrophoresis of isolated, purified basal apparatuses of S. similis identifies among other proteins two isoforms of centrin and α- and β-tubulin as intrinsic components.
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  • 71
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Low-energy reactive collisions between the protonated molecule of a trichothecene and ammonia inside the collision cell of a triple-stage quadrupole mass spectrometer produce an adduct ion, solvated ions and ions formed by substitution reactions and collisionally activated dissociation (CAD). The collision conditions have an important effect on the relative abundances. Energy- and pressure-resolved curves show that the formation of the adduct ion, substitution ions and solvated ions is favoured by high pressure of ammonia (5-9 mTorr) and low collision energy (0.1-10 eV), while the formation of CAD ions is favoured by high pressure and high energy.
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  • 72
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    Biological Mass Spectrometry 18 (1989), S. 145-146 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Qualitative and semi-quantitative analysis of monosaccharide mixtures is explored through low-energy (15 eV) electron impact mass spectrometry of their per-O-acetylated N-(p-nitrophenyl) derivatives with distinctive features on its mass spectra.
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  • 73
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A liquid-solid extraction method suitable for rapid screening of sulfonated azo dyes in municipal wastewater has been developed. The dyes (Color Index Acid Yellow 23, Red 14 and Yellow 49) were separated on a short, reversedphase liquid chromatographic column with a water-methanol gradient containing 2 mM sulfuric acid. The column effluent was directed via a split-valve to an ion spray liquid chromatography/mass spectrometry (LC/MS) interface to an atmospheric pressure ionization mass spectrometer. The ion spray LC/MS system produced abundant [M - Na]- and [M - 2Na]2- ions according to the number of sulfonic acid substituents. Collision-induced dissociation of the parent ions for the dyes studied gave the SO3-. fragment common to sulfonated compounds plus additional daughter ion fragments characteristic of each dye. The dyes were quantified by monitoring from four to six different daughter ions of each dye. The relative abundances and the sum of the daughter ion current counts were used for confirmation and quantification with external standards. Recoveries of the dyes were in the range of 70-122%, and the relative standard deviation of replicate determinations was 5.4-12%. The method detection limit was three times higher for Acid Yellow 23 compared with the other two dyes, which could be detected down to 50 ppb in municipal wastewater.
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  • 74
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    Biological Mass Spectrometry 18 (1989), S. 279-279 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 75
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    Biological Mass Spectrometry 18 (1989) 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 76
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Gas chromatographic/mass spectrometric methods have been developed for the analysis of cuticular hydrocarbon waxes from termites, ants and house flies. A combination of electron impact, chemical ionization with ethylene oxide, methane and ammonia together with methoxy mercuration followed by reductive demercuration, enabled alkane and alkene components of waxes from Reticulitermes termites, Hypoponera eduardi, Camponotus Vagus, and Cataglyphis cursor ants and Calliphora Vomitora house flies to be characterized.
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  • 77
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fast atom bombardment (FAB) combined with tandem mass spectrometry has been used to verify the amino acid sequence in Org 2766 [H-Met(O2)-Glu-His-Phe-D-Lys-(Phe-OH)] and its deuterated analogues. It is shown that FAB mass spectrometry in addition to the [M + H]+ ion yields dominantly N-terminal sequence ions and some C-terminal sequence ions. These results together permit determination of the amount of deuterium incorporated and the position of the denterated amino acids in the peptide.
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  • 78
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    Biological Mass Spectrometry 18 (1989) 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 79
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Packed capillary liquid chromatography/mass spectrometry using a moving belt interface is a practical, versatile technique for the identification of unknowns. The low flow rates (1-2 μl min-1) improve the operation of the moving belt and allow direct deposition of eluates from reversed-phase liquid chromatographic columns containing large proportions of water. Column performance and durability is equivalent to that obtained with conventional or microbore liquid chromatographic columns. Techniques have been developed for analyzing dilute solutions with no loss in column performance and for the detection of radiolabeled metabolites. Applications to analyses of polar, thermally labile compounds and environmental samples are presented.
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  • 80
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    Biological Mass Spectrometry 18 (1989), S. 106-109 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Perfluorocarbons (PFCs) can be detected by thermospray liquid chromatography/mass spectrometry (LC/MS) only when the system is operated in the negative ion mode with filament on and some water entering the thermospray source. A new mechanism for PFC ionization is proposed, based on studies of LC/MS detection of the perfluorinated forms of cyclohexane, methyl and dimethyl cyclohexane, decalin, 1-methyl decalin and toluene. The ion evaporation mechanism of Dodd, involving pre-ionization of PFCs in the presence of aqueous NH4OAc, is not operative, nor is chemical ionization of PFCs by the reagent ions as in true thermospray LC/MS. Instead, PFC ionization is attributable to the negative ions formed from the water in the source; these ions undergo prompt charge-exchange reactions with the more electronegative PFCs to form structure-retaining PFC ions.
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  • 81
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    Biological Mass Spectrometry 18 (1989), S. 131-137 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Suppression effects observed in plasma desorption (PD) mass spectrometry have been studied and compared to those found in fast atom bombardment mass spectrometry. A basic difference in the mechanism of suppression in the two techniques is demonstrated. In positive ion mode PD mass spectrometry, peptides carrying net positive charges are preferentially detected when analysed together with peptides carrying net negative charges, and in negative ion mode PD mass spectrometry, the situation is generally reversed. Based on this complementarity, PD mapping carried out by enzymatic digestion of a nitrocellulose-bound sample can in many cases yield almost complete coverage of smaller proteins.
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  • 82
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    Biological Mass Spectrometry 18 (1989), S. 122-130 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fast atom bombardment (FAB) mass spectrometry and FAB tandem mass spectrometry in negative mode can provide molecular weight and very useful structural prior information for C-glycosyl flavonoids without derivatization. Diethanolamine or thioglycerol matrix gave an abundant deprotonated molecular ion for all the studied compounds. Mass-analysed ion kinetic energy (MIKE) and collision-activated dissociation/MIKE spectra provide characteristic fragment ions which permit differentiation of the 6- and/or 8-location, and the position of O-glycosylation.
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  • 83
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method of analyzing volatile organic sampling train (VOST) samples by megabore capillary gas chromatography/mass spectrometry has been developed to enhance compound resolution and to improve the characterization of products of incomplete combustion in stack emissions. Several analytical systems were evaluated. The combination of components which gave the best overall performance consisted of a clamshell oven used to desorb the Tenax® and/or Tenax®/charcoal VOST cartridges onto an analytical trap in a commercial purge and trap unit. The purge and trap unit thermally desorbed the contents of the analytical trap onto a megabore capillary column installed in a gas chromatograph where the VOST target compounds were characterized and quantified by a computerized mass spectrometer. All VOST target compounds showed response factors with coefficients of variation of less than 25% for triplicate analyses at four concentrations. The time of analysis using the capillary column was 30% faster than the present VOST protocol that requires packed-column gas chromatography.
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  • 84
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 149-156 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of metabolites of 2,4-dinitrotoluene have been synthesized and analysed by electron impact and chemical ionization mass spectrometry. Identification characteristics of these metabolites by their mass spectra have been determined. Differentiation of isomers is made possible by electron impact ions which are characteristic to the position of the methyl group with regard to the nitro group and to the position of the carboxylic acid group with regard to the nitro group. Metabolites containing an acetyl amino group are characterized by an [M - COCH2]+. electron impact ion.
    Additional Material: 11 Ill.
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  • 85
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have examined the synthetic N-oxides of five ethylenediamine-type antihistamines using fast atom bombardment (FAB) mass spectrometry and FAB tandem mass spectrometry (MS/MS). Fragmentation of the protonated molecule in the normal and collisionally activated spectra appeared to be characteristic for this class of antihistamine N-oxide. Spectra were also acquired from an ethanolamine and a propylamine antihistamine N-oxide for comparison. These results were very similar to those obtained from biologically produced antihistamine N-oxides, as well as isomeric metabolites, which were readily distinguished from the N-oxides by characteristic fragmentation. In addition, a prominent ion 16 daltons lower in mass, which has been attributed to loss of elemental oxygen from the protonated N-oxide in chemical ionization mass spectral studies, was shown to be a matrix-dependent product of the solution-phase reduction of the antihistamine N-oxide to the parent antihistamine during FAB ionization. These results demonstrate that with a non-reducing matrix such as glycerol, FAB mass spectrometry and FAB MS/MS are excellent methods for the characterization of the non-conjugated antihistamine metabolites such as the N-oxides.
    Additional Material: 10 Ill.
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  • 86
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The in vivo biliary and urinary metabolites of (±)-N-methyl-N-(1-methyl-3,3-diphenylpropyl) formamide (1) from male Wistar rats have been characterized by gas chromatography/mass spectrometry. In urine, non-conjugated metabolites included 1,1-diphenyl-3-butanone (4) and 3-methylamino-1,1, diphenylbutane (7). β-Glucuronidase liberated 4, 1,1-diphenyl-3-butanol (5), 1,1-diphenyl-3-butanone oxime (6), N-hydroxymethyl-N-(1-methyl-3, 3-diphenylpropyl) formamide (3), 1-(4-hydroxyphenyl)-1-phenyl-3-butanone (11), 1-(4-hydroxyphenyl)-1-phenyl-3-butanone oxime (12), N-methyl-N-(1-methyl-3-(4-hydroxyphenyl)-3-phenylpropyl) formamide (8), 1-(4-hydroxy-3-methoxyphenyl)-1-phenyl-3-butanone (16), 1-(4-hydroxy-3-methoxyphenyl)-1-phenyl-3-butanol (17), 1-(4-hydroxy-3-methoxyphenyl)-1-phenyl-3-butanone oxime (18), N-(1-methyl-3-(4-hydroxy-3-methoxyphenyl)-3-phenylpropyl) formamide (14) and N-methyl-N-(1-methyl-3-(4-hydroxy-3-methoxyphenyl)-3-phenylpropyl) formamide (13). Most of the carbinolamide (3) decomposed in the gas chromatograph inlet to N-(1-methyl-3,3-diphenylpropyl) formamide (2) unless stabilized as a trimethylsilyl (TMS) derivative. In bile, compounds 1, 2, 3, 5, 6, 11, 12 and 16 were present as non-conjugated metabolites. β-Glucuronidase also liberated N-(1-methyl-3-(4-hydroxyphenyl)-3-phenylpropyl) formamide (9), and all of the previously listed compounds except 7. Trimethylsilylation of the conjugated bile fraction revealed the presence of an additional two compunds: N-hydroxymethyl-N-(1-methyl-3-(4-hydroxyphenyl)-3-phenylpropyl) formamide (10) and N-hydroxymethyl-N-(1-methyl-3-(4-hydroxy-3-methoxyphenyl)-3-phenylpropyl) formamide (15). A stable carbinolamide metabolite standard was synthesized and the mass spectral fragmentations of its TMS derivative studied by tandem mass spectroscopy. This is the first report on stable carbinolamide metabolites of high-molecular-weight formamides.
    Additional Material: 6 Ill.
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  • 87
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 713-718 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Advanced glycation products have been investigated by parent ion spectroscopy, employing B2/E = constant linked scans of furoyl ions obtained from hydrolysed glycated albumin and polylysine mixtures, without any extraction procedures. Using such an instrumental approach, together with exact mass measurements and collision spectroscopy, the identification of 2-(2-furoyl)-4-hydroxyl-1H-imidazole and 2-(2-furoyl)-4-carboxy-1H-imidazole among the advanced glycation products has been achieved.
    Additional Material: 2 Ill.
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  • 88
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 719-723 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Human cerumen was hydrolysed with base and the constituents were examined as trimethylsilyl (TMS), methyl ester/TMS, picolinyl/TMS and nicotinate/TMS derivatives by gas chromatography and gas chromatography/mass spectrometry. A sample was also reacted with osmium tetroxide for double bond location. The major constituents were cholesterol, squalene and several series of long-chain fatty acids and alcohols. These latter compounds had chain lengths of 12-26 carbon atoms and were predominantly either straight-chain saturated or straight-chain unsaturated compounds. Saturated branched-chain acids with methyl groups predominantly on even-numbered carbon atoms were present but were less abundant. Unsaturated, branched-chain acids were also present. The major unsaturated acids contained unsaturation at the delta-6-position or were derived from these acids by chain elongation. The compounds were similar to those found in vernix caseosa. The mass spectra of picolinyl esters were, for the first time, shown to be capable of determining both the position of unsaturation and methyl branching in the same molecule.
    Additional Material: 6 Ill.
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  • 89
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 727-732 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Daughter ion mass spectral data of [M + H]+ ions of leucine enkephalin and physalaemin, which were formed by fast atom bombardment, were obtained using an instrument of EBQQ configuration. In the case of leucine enkephalin, experiments were carried out in which the collision energy was varied and the collision gas pressure kept constant and vice versa. The results show that conditions can be established under which seuqence-relevant ions above m/z 200 are formed, as well as under which mainly immonium and acylium type ions are generated. Of possible interest for characterization of unknown peptides, when using hybrid instruments, are the mid-chain cleavage ions, which, at a constant argon gas pressure of 5 × 10-6 mbat, were found to maximize at around 30 eV collision energy. Daughter ion mass spectral data are also presented for [M + H]+ ions of physalaemin (mol. wt 1264). Compared to data obtained for physalaemin on multisector instruments, our results indicate that the formation of mid-chain cleavage ions is clearly enhanced.
    Additional Material: 4 Ill.
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  • 90
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The supernatants of Vero cell cultures after infection with a herpes simplex virus or a poliomyelitis virus as well as a blank were analysed by pyrolysis/direct chemical ionization mass spectrometry (Py/DCI MS). Informative pyrogrammes were obtained and used for characterization of viral proteins by applying pattern recognition methods. Differentiation of viral proteins was evaluated by analysing ‘blind’ samples. Herpes viruses could be classified correctly but the observed differences between the blank and the polio virus supernatants were too small for reliable classification of the polio viruses. Purification of the samples seems to be a prerequisite for further studies. The potential value of Py/DCI MS as a rapid non-invasive diagnostic method for viral meningoencephalitis is stressed.
    Additional Material: 3 Ill.
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  • 91
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Experimental variables in fast atom bombardment combined with tandem mass spectrometry based on low-energy collision-induced dissociation have been systematically invetigated in order to optimize parameters for analysis of synthetic lipo-oligopeptides. The parameters studied were matrix, ion polarity, collision gas, collision gas pressure and collision energy. The optimal parameters recommended in this study have been applied to the N-terminal amino acid seuquence determination of lipopeptide obtained from Nocardia rubra cell wall skeleton. Daughter and parent ion experiments with negative ion fast atom bombardment combined with tandem mass spectrometry have proven to be very useful for structure elucidation of a complex mixture of lipo-oligopeptides.
    Additional Material: 5 Ill.
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  • 92
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 775-779 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The technique of gas chromatography/tandem mass spectrometry is applied to the analysis of bis(chloromethyl) ether in laboratory and production environments. A selected reaction monitoring method is shown to yield superior sensitivity and selectivity to previous methods. A detection limit of ∼1 ppt is established even for chemically complex atmospheres which have proved intractable by previous techniques.
    Additional Material: 6 Ill.
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  • 93
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 816-819 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In studies where (2-13C)acetate is employed as isotopic tracer in vivo, we have reported a selected ion monitoring gas-liquid chromatographic/mass spectrometric method which allows plasma tracer enrichment as well as plasma acetate content to be determined in the same 200-500 μl sample through the use of methacrylic acid as the assay internal standard. For standard solutions in the range equivalent to plasma acetic acid concentrations of 10-200 μM, assay precision was ±4.3%. For plasma samples in the physiological range (approximately 20-300 μM acetate) assay precision averaged better than ±5%. The use of the method is illustrated by measuring acetate turnover in a young adult.
    Additional Material: 5 Ill.
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  • 94
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. i 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 95
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 241-246 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fast atom bombardment mass spectrometry in combination with collisional activation has been used to investigate a number os amino- and phosphate-substituted glucoses and of phosphate- and sulphate-substituted glucosamines. The collisional activation spectra of the [M - H]- ions readily reveal the presence of sulphate or phosphate substituents, whereas specific fragmentation reactions can be used to distinguish among the various positional isomers. The fragmentation of the pseudomolecular cations depends on the number of Na atoms incorporated. By selecting the appropriate pseudomolecular ion it is possible to get information on the nature and/or position of the substituents.
    Additional Material: 8 Tab.
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  • 96
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 253-257 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Full-scan capillary zone electrophoresis/mass spectrometry and capillary zone electrophoresis/tandem mass spectrometry (CZE/MS/MS) are demonstrated for the determination of monosulfonated and polysulfonated azo dyes at the low picomole levels. Under selected ion monitoring conditions femtomole levels of the dyes are detectable. Ion evaporation via the ion spray liquid chromatography/mass spectrometry interface is a mild form of ionization exhibiting only deprotonated singly charged or poly-deprotonated multiply charged negative molecular ions for sulfonated azo dyes. CZE/MS/MS daughter ion scanning after collision-induced dissociation of the molecular species for all sulfonated azo dyes contained the sulfonate ion (m/z 80). The presence of three sulfonated azo dyes in a wastewater extract was confirmed by parent ion scanning for the sulfonate daughter ion (m/z 80).
    Additional Material: 6 Ill.
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  • 97
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989), S. 258-264 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Platelet activating factor (PAF) bioactivity has been demonstrated in saliva from normal volunteers. We sought structural confirmation and evidence of heterogeneity in the 1-O-alkyl chain of the acetyl glyceryl ether phosphoryl choline (AGEPC) extracted from saliva by employing stable isotope dilution techniques in conjunction with gas chromatography/mass spectrometry. The method described involves removal of the polar phosphocholine moiety, accounts for acetyl group migration, and allows for acylation of the resultant free hydroxyl with pentafluorobenzoyl chloride. Thin-layer chromatography (TLC) purification is undertaken after phospholipase C cleavage and again after pentafluorobenzoyl chloride derivatization. The majority of the ion current is represented in the molecular anion, allowing measurement of 50 pg in biological fluid with a signal-to-noise ratio of ≥9. In one subject with markedly increased salivary PAF levels, we found evidence for molecular heterogeneity of AGEPC with production of not only C16:0 but also C18:0 and C18:1 in the alkyl chain. This technique, by using TLC in lieu of high-performance liquid chromatography, avoids potentially confounding trace contamination effects, produces spectra with few interfering signals and increases sample throughput.
    Additional Material: 5 Ill.
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  • 98
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 18 (1989) 
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 99
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several structurally similar, biologically active macrocyclic trichothecenes were ionized under thermospray conditions followed by collisionally activated dissociation of the ammonium adducts. Most of the observed daughter ions were formed by bond cleavage at the exocyclic ester bridges. Compounds with similar ester bridges formed several common daughter ions and underwent similar neutral losses. Fragmentation pathways proposed for the dissociation of the adducts were confirmed from the corresponding neutral loss spectra. Simple experiments designed for the sequential monitoring of the characteristic daughter ions were used for the rapid, direct and accurate analysis of macrocyclic trichothecenes in real samples. The primary drawback of the method is its inability to distinguish between isomers.
    Additional Material: 11 Ill.
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  • 100
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fast atom bombardment (FAB) mass spectrometry has been successfully applied to the analysis of partially modified retro-inverso peptide isomers. The spectra are characterized by abundant protonated molecular ions and also by sequence ions due to fragmentation of the inverted bonds. Unambiguous information, as to the nature and the position in the backbone of the amino acids involved in the partial modification of the structure, are given by using a combination of FAB mass spectrometry and partial, selective acid hydrolysis, without separation of the resulting peptide mixtures.
    Additional Material: 6 Ill.
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