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  • Chemistry  (11)
  • Gas chromatography  (3)
  • General Chemistry  (2)
  • Human  (2)
  • 1995-1999  (16)
  • 1
    ISSN: 1432-0878
    Keywords: Key words: Elastic fibres ; Placental stem villi ; Extravascular smooth muscle cells ; Adhesion plaques ; Talin immunoreactivity ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The stroma of human placental stem villi is believed to consist only of reticular and collagen fibres. In the present study we were able to show for the first time by light (orcein staining) and electron microscopy large amounts of elastic fibres in the stem villous stroma. Electron microscopically, homogeneous elastin was found alone or in association with microfibrils. In addition, microfibrils were observed forming long bands. These three structures, generally known to form elastic connective tissue, were seen in close connection with placental extravascular smooth muscle cells, which belong to the perivascular contractile sheath (PVCS) of stem villi. Elastin was associated with these smooth muscle cells and connected to collagen fibres via microfibrils. Collagen fibres were additionally interconnected by spike-like structures. Extravascular smooth muscle cells revealed numerous adhesion plaques which occupied conspicuously long cytoplasmic faces of the plasma membrane. In cryostat sections, immunoreactivity of talin, an attachment protein of adhesion plaques linking intracellular α-actin filaments with extracellular fibronectin, was detected in extravascular and vascular (media) smooth muscle cells. The arrangement of placental extravascular smooth muscle cells, elastic and collagen fibres suggests a functional myofibroelastic unit within the PVCS, which surrounds the large foetal blood vessels possibly contributing to elasticity and supporting tensile and/or contracting forces within the stem villi.
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  • 2
    ISSN: 1432-0878
    Keywords: Key words: Placental stem villi ; Perivascular contractile sheath ; Molecules of adhesion plaques ; Extracellular matrix molecules ; Immunocytochemistry ; Human
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. In previous studies, we have shown that smooth muscle cells and myofibroblast subpopulations of the perivascular stem villous sheath of the human placenta contain focal adhesion plaques and talin immunoreactivity. The close association of these cells to elastic and collagen fibres have led to the assumption of a functional myofibroelastic unit within the perivascular stem villous sheath. Interactions between the extracellular matrix and smooth muscle cells depend on a variety of structural protein assemblies. In the present study, we examined, by immunocytochemistry, whether the molecular assembly of extracellular matrix proteins and molecules of focal adhesions, known to be essential for signal transduction in smooth muscle cells, are also found in smooth muscle cells of the perivascular stem villous sheath of the human placenta. Vascular and extravascular smooth muscle cells were immunoreactive for α-actinin, vinculin, paxillin and tensin, the integrin chains α1 and β1, and the basement membrane components laminin and heparan/-chondroitin sulfate proteoglycan perlecan. pp125FAK did not react. In the extracellular matrix of blood vessel walls and the perivascular stem villous sheath, we found immunoreactivity of fibronectin and collagen types I, VI and undulin (collagen type XIV). From our data we conclude that within the perivascular stem villous sheath, there exists a system of signal transduction molecules, indicating a cross talk between the smooth muscle cells of this sheath and their surrounding extracellular matrix.
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  • 3
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Column liquid chromatography ; Polychlorinated biphenyls ; Cod liver oil
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary By application of a chromatographic column filled with Supelclean ENVI-Carb/Celite and elution with three solvents of different polarity three PCB fractions were obtained. Fraction A contained poly-ortho PCBs, Fraction B mono-ortho PCBs, and Fraction C non-ortho PCBs. The Supelclean ENVI-Carb/Celite column was used in combination with a sample preparation procedure for pre-cleaning of acid-stable chlorinated hydrocarbons such as DDT and its metabolites, HCH isomers, and regulation-relevant PCB congeners. The method was optimized using standard solutions of 55 PCB congeners, 8 chlorinated pesticides and contaminated cod liver oil samples. The influence of traces of remaining matrix on the elution profile of the organochlorine compounds on Supelclean ENVI-Carb/Celite was observed. Quantitation was carried out by GC-ECD with fused silica capillary columns of different polarity.
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  • 4
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Microwave extraction ; Sample clean-up ; Organochlorine compounds ; Blubber of marine mammals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A rapid and effective method is described for the extraction of organochlorine compounds (PCB 153, PCB 138, PCB 180, p,p′-DDE, α-HCH, γ-HCH, ε-HCH and HCB) from seal blubber and pork fat withn-hexane using a microwave technique. Heating of the non-polarn-hexane was achieved using a microwave transformer. The lipid content of the samples obtained by this extraction was identical to that by Soxhlet extraction. After separation of sample matrix and organochlorines on a silica gel column the organochlorine compounds were determined by GC-ECD. The efficiency of the method was tested with 500 mg spiked fat, extracted using various numbers of extraction cycles. Recoveries of organochlorine compounds in grey seal blubber and spiked pork fat generally exceeded 90 %.
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  • 5
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Chiral stationary phases ; Enantioseparation ; Toxaphene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation of the enantiomers of the compounds of technical toxaphene (CTTs) on heptakis(6-O-tert-butyldimethylsilyl-2,3-di-O-methyl)-β-cyclodextrin (β-TBDM) has been studied by gas chromatography with electron-capture detection (GC-ECD). Enantiomers of eight of the nine CTTs under investigation were separated on this chiral stationary phase. Separations of the enantioners of CTTs have hitherto been achieved ontert-butyldimethylsilylated β-cyclodextrin (β-BSCD). The chiral resolution values and separation factors of the CTTs on β-TBDM have been compared with those obtained on β-BSCD. Although several components coeluted, enantioselective determination of three CTTs was possible in an extract of seal blubber. For each CTT the first-eluting enantiomer was enantioenriched. Enantioselective accumulation of2-endo, 3-exo,5-endo,6-exo,-8,8,9,10-octachlorobornane (B8-1412) in biota has been established for the first time.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 20 (1997), S. 85-93 
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Modified cyclodextrin phases ; Chiral organochlorines ; Biological samples ; Enantiomeric ratios ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Four chiral stationary phases containing modified cyclodextrines diluted in or chemically bonded to a non-chiral phase were used to resolve chiral organochlorine compounds such as α-hexachlorocyclohexane (α-HCH), perdeuterated α-HCH (α-PDHCH), β-and γ-pentachlorocyclohexene (PCCH), oxychlordane, cis-and trans-chlor- dane, cis- and trans-heptachlorepoxide, PCB 95, PCB 132, PCB 149, and Chiral tozaphenes.The elution order was determined by analyzing standards with known enantiomeric excesses.Furthermore, an internal standard was used to even out slight variations in the ratio of peak hights of enantiomers which were determined from injection to injection.None of the chiral stationary phases resolved all chiral organochlorine compounds. However, the β-TBDM(35% heptakis (6-O-t-butyldimethylsilyl-2,3-di-O-methyl)-β-cyclodextrin in OV 1701) column allowed the separation of all compounds under investigation except for PCB 95 and chiral toxaphenes.Emphasis was placed on the separation of as many as possible enantiomers on a chiral phase by application of one temperature program and with respect to unambiguous quantitation of biological samples such as bludder and liver of marine and terrestrial mammals.
    Additional Material: 7 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 18 (1995), S. 643-646 
    ISSN: 0935-6304
    Keywords: Gas chromatography/Mass spectrometry ; Chiral GC ; Deuterium-labeled compounds ; Hexachlorocyclohexane ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Perdeuterated α-1,2,3,4,5,6-hexachlorocyclohexane (α-PDHCH) was synthesized and isolated in pure form. α-PDHCH was baseline separated from unlabeled α-HCH by high resolution gas chromatography on different stationary phases. α-PDHCH was also resolved into its enantiomeric forms by application of a chiral GC phase. Furthermore, chiral chromatography of a mixture of labeled α-PDHDH and unlabeled α-HCH resulted in four peaks. Standard solutions of α-PDHCH are recommended both as recovery standard for sample clean-up and as internal standard for the quantitation of chlorinated hydrocarbons with GC/MS or GC/ECD in environmental samples.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1022-1336
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The porous copolymer films of N-methacryloyl-L-alanine methyl ester and diethyleneglycol-bis-allylcarbonate (diallyl oxydiethylene dicarbonate) were hydrolyzed with 1 M NaOH solution for 40 min at 25°C. The pores of the films showed pH response in diameter. The pore diameter of 3,7 μm in the buffer solution of pH 3 was closed completely at pH 5.
    Additional Material: 4 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 67 (1995), S. 1184-1185 
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 67 (1995), S. 1185-1186 
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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