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  • Cell & Developmental Biology  (1,697)
  • Analytical Chemistry and Spectroscopy  (1,522)
  • 1990-1994  (3,219)
  • 1985-1989
  • 1970-1974
  • 1965-1969
  • 1992  (3,219)
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  • 1990-1994  (3,219)
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  • 1
    ISSN: 0886-1544
    Keywords: activation ; fertilization ; microtubules ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Centrosomes are undetectable in unfertilized sea urchin eggs, and normally the sperm introduces the cell's microtubule-organizing center (MTOC) at fertilization. However, artificial activation or parthenogenesis triggers microtubule assembly in the unfertilized egg, and this study explores the reappearance and behavior of the maternal centrosome. During activation with A23187 or ammonia, microtubules appear first at the cortex; centrosomal antigen is detected diffusely throughout the entire cytoplasm. Later, the centrosome becomes more distinct and organizes a radial microtubule shell, and eventually a compact centrosome at the egg center organizes a monaster. In these activated eggs, centrosomes undergo cycles of compaction and decompaction in synchrony with the chromatin, which also undergoes cycles of condensation and decondensation. Parthenogenetic activation with heavy water (50% D2O) or the microtubule-stabilizing drug taxol (10 μM) induces numerous centrosomal foci in the unfertilized sea urchin egg. Within 15 min after incubation in D2O, numerous fine centrosomal foci are detected, and they organize a connected network of numerous asters which fill the entire egg. Taxol induces over 100 centrosomal foci by 15 min after treatment, which organize a corresponding number of asters. The centrosomal material in either D2O- or taxol-treated eggs aggregates with time to form fewer but denser foci, resulting in fewer and larger asters. Fertilization of eggs pretreated with either D2O or taxol shows that the paternal centrosome is dominant over the maternal centrosome. The centrosomal material gradually becomes associated with the enlarged sperm aster. These experiments demonstrate that maternal centrosomal material is present in the unfertilized egg, likely as dispersed undetectable material, which can be activated without paternal contributions. At fertilization, paternal centrosomes become dominant over the maternal centrosomal material. © 1992 Wiley-Liss, Inc.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    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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  • 3
    ISSN: 0886-1544
    Keywords: Chloroplast movement ; phytochrome ; near infrared laser ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The cell of the green alga Mougeotia orients its chloroplast by rotation, according to the direction or polarization of incident red light. The mechanics of the rotation is described by the angle of rotation and the angular velocity of the rotator (i.e., the chloroplast). We developed a laser diffractometer to determine the angle of rotation of the chloroplast. The angle of rotation of the chloroplast shifted by a constant angular velocity, and hence, the net torque on the chloroplast was zero. This suggests that the driving torque acting on the chloroplast is always balanced by the viscous torque. The maximal driving force acting on the chloroplast was estimated to be nearly equal to the force generated by an actomyosin system. This is the first measurement of the driving force acting on the chloroplast in Mougeotia. The amplitude of the force supported the anchorage site hypothesis. However, it remains unclear whether or not the angular independence of the force also supports the hypothesis. © 1992 Wiley-Liss, Inc.
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  • 4
    ISSN: 0886-1544
    Keywords: division polarity ; F-actin ; microtubules ; plastids ; preprophase band ; stomata ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Stomatogenesis, the determinate developmental pathway leading to formation of a pair of specialized guard cells, was studied in monoplastidic cells ofSelaginella. Observations of living cells followed by immunofluorescence microscopy of the same cells made it possible to correlate changes in cytoskeletal organization with developmental events. The guard mother cell divides in a plane perpendicular to previous divisions and this shift in polarity is marked by morphogenetic plastid migration, as well as by extensive reorganization of cytoskeletal arrays. The single plastid divides and daughter plastids move to a position opposite each other (incipient spindle poles). The axis defined by the opposing plastids rotates in the cell before becoming fixed in position with polar plastids adjacent to the lateral anticlinal walls. Plastid polarity predicts spindle orientation and the plane of division. Once division polarity is defined by plastid position, which will remain unchanged throughout mitosis and cytokinesis, cortical microtubules become reorganized from radial to longitudinal (relative to the long axis of the leaf). The initially random cortical F-actin also becomes aligned longitudinally. A wide preprophase band of microtubules and F-actin is formed at right angles to the spindle axis. Plastid-based microtubules establish the preprophase spindle and also connect to the preprophase band. The mitotic spindle remains anchored at the polar plastids. After mitosis, a phragmoplast that forms among microtubules emanating from plastids and nuclei develops in the plane marked previously by the preprophase band. Mitosis is completed in 1 h 15 min ± 3 min (mean ± S.E.). © 1992 Wiley-Liss, Inc.
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 21 (1992), S. 74-82 
    ISSN: 0886-1544
    Keywords: motion analysis ; sperm activation ; K+inhibition ; Fluo-3 ; eukaryotic flagella ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We investigated the swimming patterns of trout sperm using computer-assisted analyses of video microscopy. Under full activation conditions, in which 80-100% of sperm activate their motility, sperm swim in circular paths for 2-5 sec, followed by 30-60 sec of a more linear swimming, and, finally, cessation of movement, with a straightening of the flagella. Threshold activation, in which 50% of the sperm activate, is characterized by circular patterns of swimming for less than 20 sec, with straightened flagella upon cessation. Full activation and threshold activation are observed in low-K+ solution or in an Mg++ -supplemented K+ solution. Similarities in swimming patterns in low-K+ solution and in a Mg++ -supplemented K+ solution suggest a common underlying mechanism of activation. Initiation of movement in solutions with high Ca++ to K+ ratio is similar to activation in K+ -free solution. However, sperm in Ca++ -supplemented media resume circular swimming within 20-25 sec after activation, and, upon cessation of movement, the flagella are frequently cane shaped or bent. Differences in swimming patterns upon activation by high Ca++ concentration suggest additional effects of Ca++ on regulating swimming patterns. We used the fluorescent Ca++ indicator Fluo-3 to measure changes in intracellular Ca++ concentration upon activation. Intracellular Ca++ concentration transiently increases upon activation, with peak Ca++ concentration coinciding with the period of circular swimming. This transient increase in Ca++ concentration is seen in the absence of external Ca++, providing strong evidence for the released of Ca++ from intracellular stores upon activation.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 21 (1992), S. 101-110 
    ISSN: 0886-1544
    Keywords: F-actin ; silk gland ; phalloin ; periluminal circumferential actin bundles ; actin-coated vacuoles ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Labeling of silk glands with rhodaminyl-phalloin shows that most F-actin is restricted to parallel bundles that form rings around the gland lumen at the apical cell surface. The bundles are lost when larval feeding stops at moulting, and the F-actin is redistributed through the cytoplasm as coats to vacuoles and, occasionally, in variably oriented strands. After moulting there is a return to the distribution of filamentous actin in the apical periluminal rings of bundles. These events occur at the same time as F-actin in the nuclear shell [Henderson and Locke, submitted] undergoes its own set of changes. In silk gland cells two kinds of f-actin deployment take place concurrently.
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  • 7
    ISSN: 0886-1544
    Keywords: myofibrils ; extracellular matrix ; cytoskeleton ; integrins ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The influence of the extracellular matrix (ECM) on cell behavior, myofibrillogenesis and cytoarchitecture was investigated in neonatal rat cardiac myocytes in vitro. Cell behavior was examined by analyzing cell spreading on different ECM components under a variety of experimental conditions. Area measurements were made on digitized images of cells grown for various time intervals on fibronectin (FN), laminin (LN), collagens I and III (C I + III), plastic, and bovine serum albumin (BSA). The amount of spreading was varied on the different matrices and was maximal on FN 〉 LN 〉 C I+III 〉 plastic 〉 BSA. Addition of anti-β1 integrin antibodies to myocytes cultured on FN, LN and C I+III blocked spreading outward on the substrates and altered normal myofibrillogenesis, especially on LN. Concomitantly, the integrin antibodies induced the formation of giant pseudopodial processes which protruded upward from the substrates. These pseudopods contained actin polygonal networks which exhibited a regular geometrical configuration.Effects of the ECM on cytoarchitecture was examined by analyzing the temporal and spatial patterns of fluorescence and immunogold labeling of cytoskeletal and integrin proteins as myocytes spread in culture. The first indication of sarcomeric patterns was the appearance at 4 hours of striations formed by lateral alignment of α-actinin aggregates into Z bands. At later times, vinculin at 8 hours and β integrin at 22 hours became co-localized with α-actinin at the Z bands and focal adhesions. These data indicate that ECM components influence myocyte spreading and that myofibril assembly and/or stability is associated with ECM-integrin-cytoskeleton associations.
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  • 8
    ISSN: 0886-1544
    Keywords: cardiac muscle ; actin dynamics ; α-actinin ; vinculin ; microinjection ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: When fluorescently labeled contractile proteins are injected into embryonic muscle cells, they become incorporated into the cells' myofibrils. In order to determine if this exchange of proteins is unique to the embryonic stage of development, we isolated adult cardiac myocytes and microinjected them with fluorescently labeled actin, myosin light chains, α-actinin, and vinculin. Each of these proteins was incorporated into the adult cardiomyocytes and was colocalized with the cells'native proteins, despite the fact that the labeled proteins were prepared from noncardiac tissues. Within 10 min of injection, α-actinin was incorporated into Z-bands surrounding the site of injection. Similarly, 30 sec after injection, actin was incorporated into the entire I-bands at the site of injection. Following a 3-h incubation, increased actin fluorescence was noted at the intercalated disc. Vinculin exchange was seen in the intercalated discs, as well as in the Z-bands throug hout the cells. Myosin light chains required 4-6 h after injection to become incorporated into the A-bands of the adult muscle. Nonspecific proteins, such as fluorescent BSA, showed no association with the myofibrils or the former intercalated discs. When adult cells were maintained in culture for 10 days, they retain the ability to incorporate these contractile proteins into their myofibrils. T-tubules and the sarcoplasmic reticulum could be detected in periodic arrays in the freshly isolated cells using the membrane dye WW781 and DiOC3[3], respectively. In conclusion, the myofibrils in adult, as in embryonic, muscle cells are dynamic structures, permitting isoform transitions without dismantling of the myofibrils.
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  • 9
    ISSN: 0886-1544
    Keywords: MAP p15 ; microtubule bundling ; trypanosoma brucei ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A protein of 15 kDa (p15) was isolated from Trypanosoma brucei subpellicular microtubules by tubulin affinity chromatography. The protein bound tubulin specifically both in its native form and after SDS-PAGE in tubulin overlay experiments. p15 promoted both the in vitro polymerization of purified calf brain tubulin and the bundling of preformed mammalian microtubules. Immunolabeling identified p15 at multiple sites along microtubule polymers comprising calf brain tubulin and p15 as well as on the subpellicular microtubules of cryosectioned trypanosomes. Antibodies directed against p15 did not cross react with mammalian microtubules. It is suggested that p15 is a trypanosome-specific microtubule-associated protein (MAP) that contributes to the unique organization of the sub-pellicular microtubules.
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  • 10
    ISSN: 0886-1544
    Keywords: microtubules ; vesicles ; cytoplasmic movement ; monoclonal antibody ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A cytoskeletal apparatus is involved in the movement of vesicles, organelles, and gametes in the pollen tube. The function of microfilaments has been defined quite precisely, but the role of microtubules needs to be further clarified. On the basis of immunological and biochemical investigations, we have identified a polypep-tide showing common properties with kinesin, a microtubule-based motor mainly described in nonplant tissues, in the pollen tube of Nicotiana tabacum. Like mammalian kinesin, the kinesin-immunoreactive homolog from Nicotiana tabacum pollen tubes binds to mammalian microtubules in an AMP-PNP dependent manner. The kinesin-like component is likely to be involved in the movement of vesicular material in the growing pollen tube.
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  • 11
    ISSN: 0886-1544
    Keywords: actin ; acidic vesicles ; Ca2+ ; pH ; motility ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Unfertilized eggs of the sea urchin Arbacia punctulata contain pigment granules distributed throughout their cytoplasm. During the first 15 minutes after fertilization, these vesicles move out to the cortex where they become firmly anchored. We have used time-lapse video differential interference microscopy to analyze the motility of these organelles in unfertilized and fertilized Arbacia eggs. Pigment granules exhibit saltatory movement in both unfertilized and fertilized eggs. Quantitation of vesicle saltations before and after fertilization demonstrates that while there is no significant difference in the speed or pathlength of vesicle movement, there is a dramatic change in the orientation of these saltations. Saltations in the unfertilized egg are very non-radial and are as likely to be directed toward the cortex as away. In contrast, saltations in the fertilized egg are more radially oriented and more likely to be cortically directed. This transition must reflect underlying changes in the cellular structures necessary for pigment granule saltations. The change in the orientation of pigment granule saltations following fertilization requires both a transient increase in the cytoplasmic concentration of Ca2+ and an elevation of cytoplasmic pH. Similarly, the ability of pigment granules to adhere to the cortex requires both the transient elevation of cytoplasmic Ca2+ and the alkalinization of the cytoplasm. As the reorganization of cortical actin at fertilization is regulated by these ionic fluxes, and both movement and adhesion are sensitive to cytochalasins, we hypothesize that the alterations in directed motility and adhesion reflect underlying changes in the actin cytoskeleton.
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  • 12
    ISSN: 0886-1544
    Keywords: bioluminescence ; ATP depletion ; motility ; flagellum ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The initiation of motility and modification of energy metabolism of rat caudal epididymal spermatozoa can be induced by dilution in a saline medium. We have investigated in these cells the relationships between the energy reserve (sperm ATP content measured by bioluminescence) and flagellar movement (high speed videomicrography, 200 frames/sec). A steady state was observed in sperm ATP content, progressive velocity (Vp) and flagellar beat frequence (F) with sperm dilution in a medium with glucose, lactate, pyruvate and acetate substrates after 30 minutes of incubation, without these substrates, changes in metabolic pathways occurred immediately and initially disturbed the relationship between ATP levels and F, suggesting differences in motility initiation when energy is from an endogenous origin via mitochondrial oxidative phosphorylation. This “energy crisis” was reversed by the addition of substrates to the medium.The three-dimensional flagellar movement observed in the presence of substrates quickly became two-dimensional in their absence. The flagellar beat envelope became more splayed, the mean amplitude of lateral head displacement increased and F decreased. The resulting high flagellar beat efficiency can be compared to that observed during hyperactivation which is a physiological event related to a fall in intracellular ATP level. In both media, the displacement of the flagellum in relation to the wave axis varied sinusoidally. The sine period increased with time when the spermatozoa were incubated in the medium without substrates. These results suggest a gradual slowing-down of the velocity of wave formation in the proximal part of the flagellum.
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  • 13
    ISSN: 0886-1544
    Keywords: actin polymerization ; cell elongation ; photoreceptor ; cytoskeleton ; phalloidin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the retinas of teleost fish, rod photoreceptors elongate in response to light. Light-activated elongation is mediated by the myoid of the rod inner segment and is actin-dependent. Inner segment F-actin filaments form bundles running parallel to the cell's long axis. We examined the mechanism of rod elongation using mechanically-detached rod fragments, consisting of the motile inner segment and sensory outer segment (RIS-ROS). When RIS-ROS are isolated from darkadapted green sunfish and cultured in the light, they elongate 15μm at 0.3-0.6μm/min. Elongation was inhibited 65% by 0.1μM Cytochalasin D, suggesting a requirement for actin assembly. To determine the extent of assembly during elongation, we used three approaches to measure the F-actin content in RIS-ROS: detection of pelletable actin by SDS-PAGE after detergent-extraction of RIS-ROS; quantification of fluorescein-phalloidin binding by fluorimetry, fluorescence-activated cell sorting and image analysis; estimation of total F-actin filament length by electron microscopy. All three assays indicated that no net assembly of RIS-ROS F-actin accompanied myoid elongation. An increase in F-actin content within the elongated myoid was counterbalanced by a decrease in F-actin content within the 13 microvillus-like calycal processes located at the end of the inner segment opposite to the growing myoid. O'Connor and Burnside (Journal of Cell Biology 89:517-524, 1981) showed that minus-ends of rod F-actin filaments are oriented towards the elongating myoid while plus-ends are oriented towards the shortening calycal processes. Our observations suggest that RIS-ROS elongation entails actin polymerization at the minus-ends of filaments coupled with depolymerization at the filament plus-ends.
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  • 14
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    Electronic Resource
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 21 (1992), S. 281-292 
    ISSN: 0886-1544
    Keywords: ATPase ; CTPase ; minus-end-directed microtubule motility ; cytoplasmic dynein ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Extracts of unfertilized sea urchin eggs contain at least two isoforms of cytoplasmic dynein. One exhibits a weak affinity for microtubules and is primarily soluble. The other isoform, HMr-3, binds to microtubules in an ATP-sensitive manner, but is immunologically distinct from the soluble egg dynein (Porter et al.: Journal of Biological Chemistry 263:6759-6771, 1988). We have now further distinguished these egg dynein isoforms based on differences in NTPase activity. HMr-3 copurifies with NTPase activity, but it hydrolyzes CTP at 10 times the rate of ATP. The soluble egg dynein is similar to flagellar dynein in its nucleotide specificity; its MgCTPase activity is ca. 60% of its MgATPase activity. Non-ionic detergents and salt activate the MgATPase activities of both enzymes relative to their MgCTPase activities, but this effect is more pronounced for the soluble egg dynein than for HMr-3. Sucrose gradient-purified HMr-3 promotes an ATP-sensitive microtubule bundling, as seen with darkfield optics. We have also isolated a 20 S microtubule translocating activity by sucrose gradient fractionation of egg extracts, followed by microtubule affinity and ATP release. This 20 S fraction, which contains the HMr-3 isoform, induces a microtubule gliding activity that is distinct from kinesin. Our observations suggest that soluble dynein resembles axonemal dynein, but that HMr-3 is related to the dynein-like enzymes isolated from a variety of cell types and may represent the cytoplasmic dynein of sea urchin eggs.
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  • 15
    ISSN: 0886-1544
    Keywords: cytoskeleton ; globoside ; vimentin ; desmin ; keratin ; glial fibrillary acidic protein ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: We reported recently that two glycosphingolipids (GSLs), globoside (Gb4)and ganglioside GM3, colocalized with vimentin intermediate filaments of human umbilical vein endothelial cells. To determine whether this association is unique to endothelial cells or to vimentin, we analyzed a variety of cell types. Doublelabel immunofluorescent staining of fixed, permeabilized cells, with and without colcemid treatment, was performed with antibodies against glycolipids and intermediate filaments. Globoside colocalized with vimentin in human and mouse fibroblasts, with desmin in smooth muscle cells, with keratin in keratinocytes and hepatoma cells, and with glial fibrillary acidic protein (GFAP) in glial cells. Globoside colocalization was detected only with vimentin in MDCK and HeLa cells, which contain separate vimentin and keratin networks. GM3 ganglioside also colocalized with vimentin in human fibroblasts. Association of other GSLs with intermediate filaments was not detected by immunofluorescence, but all cell GSLs were detected in cytoskeletal fractions of metabolically labelled endothelial cells. These observations indicate that globoside colocalizes with vimentin, desmin, keratin and GFAP, with a preference for vimentin in cells that contain both vimentin and keratin networks. The nature of the association is not yet known. Globoside and GM3 may be present in vesicles associated with intermediate filaments (IF), or bound directly to IF or IF associated proteins. The prevalence of this association suggests that colocalization of globoside with the intermediate filament network has functional significance. We are investigating the possibility that intermediate filaments participate in the intracellular transport and sorting of glycosphingolipids.
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  • 16
    ISSN: 0886-1544
    Keywords: nonmuscle myosin ; antibodies ; neurons ; blood vessels ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The distribution of nonmuscle myosin isoforms in brain and aorta was studied by using polyclonal antibodies against two synthetic peptides selected from a region near the carboxyl terminus of bovine brain (peptide IIB) and human macrophage (peptide IIA) myosin. Immunoblots of brain homogenates and purified myosin showed two major bands stained by anti-peptide IIB (MIIB1 and MIIB2) and a minor band stained by anti-peptide IIA (MIIA2). Polyclonal anti-human platelet myosin antibodies did not react with MIIB isoforms. In cryosections from bovine, rat, and mouse brains, anti-peptide IIB stained most neuronal cells. In bovine cryosections, glial staining was also observed. In contrast, anti-peptide IIA and anti-platelet myosin antibodies primarily stained blood vessels. In bovine aorta, the anti-peptide antibodies recognized four bands, MIIB3, MIIB4, MIIA1, and MIIA2. Only MIIA2 was recognized by anti-human platelet myosin antibodies. In bovine aorta cryosections, anti-peptide IIB stained smooth muscle cells in tunica intima and tunica media but did not stain endothelial cells. Anti-peptide IIA stained smooth muscle cells in the tunica media, and endothelial cells of vaso vasorum but not of aorta. Only polyclonal anti-platelet myosin antibodies stained the endothelial cells of aorta tunica intima. These results indicate that multiple isoforms of cellular myosins exist in mammals, that these isoforms are expressed in a cell specific manner, and that the major myosin isoforms isolated from whole brain originate from neurons and, at least in bovine brain, from glia, but not from blood vessels. © 1992 Wiley-Liss, Inc.
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  • 17
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    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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  • 18
    ISSN: 0886-1544
    Keywords: epidermal keratinocytes ; cytoskeleton ; UV induced reorganization ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Indirect immunofluorescence microscopy has been used to investigate the ultraviolet (UV) radiation induced disruption of the organization of microfilaments, keratin intermediate filaments, and microtubules in cultured human epidermal keratinocytes. Following irradiation, concurrent changes in the organization of the three major cytoskeletal components were observed in cells incubated under low Ca2+ (0.15 mM) conditions. UV irradiation induced a dose-dependent condensation of keratin filaments into the perinuclear region. This collapse of the keratin network was accompanied by the reorganization of microfilaments into rings and a restricted distribution of microtubules, responses normally elicited by exposure to high Ca2+ (1.05 mM) medium. The UV induced alteration of the keratin network appears to disrupt the interactions between keratin and actin, permitting the reorganization of actin filaments in the absence of Ca2+ stimulation.In addition to the perinuclear condensation of keratin filaments, UV irradiation inhibits the Ca2+ induced formation of keratin alignments at the membrane of apposed cells if UV treatment precedes exposure to high Ca2+ medium. Incubation of keratinocytes in high Ca2+ medium for 24 hours prior to irradiation results in the stabilization of membrane associated keratin alignments and a reduced susceptibility of cytoplasmic keratin filaments to UV induced disruption. Unlike results from investigations with isogenic skin fibroblasts, no UV induced disassembly of microtubules was discernible in irradiated human keratinocytes. © 1992 Wiley-Liss, Inc.
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  • 19
    ISSN: 0886-1544
    Keywords: spermatozoa ; flagella ; motility ; epididymis ; maturation ; mammal ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Motility and flagellar movement of ram spermatozoa along the epididymis were analysed in vitro. From the caput to the cauda of the epididymis, the percentage of motile and progressive spermatozoa increases. No flagellar bending was observed in spermatozoa from the testis or the epididymal anterior caput. When spermatozoa reached the distal caput of the epididymis, a static curvature, associated with an initiation of the flagellar beating, appeared on the flagella. This curvature normally disappeared during epididymal transit. Its disappearance was associated with an increase in the flagellar beat efficiency. Our results suggest that the initiation of motility is related to two mechanisms involving: (1) the presence of a transient static curvature, and (2) the establishment of a symmetric regular beating of the flagellum. © 1992 Wiley-Liss, Inc.
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  • 20
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 229-229 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 21
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. i 
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 22
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 23
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 24
    ISSN: 0886-9383
    Keywords: Predictive ability ; Regression ; PLS ; SDEP ; Cross-validation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The standard deviation of prediction errors (SDEP) is used to evaluate and compare the predictive ability of some regression models, namely MLR, ACE and linear and non-linear PLS, the last being the best one. The parameter is determined by a cross-validation approach as an average of several runs obtained on forming groups in a random way. The variation in SDEP with the number of latent variables in PLS is also discussed.
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  • 25
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0886-9383
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 26
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 177-188 
    ISSN: 0886-9383
    Keywords: PLS ; Prediction error ; Background constituents ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A modification of a technique proposed by Lorber and Kowalski for the estimation of prediction errors is presented. The method is applied to five data sets. The results show that for some data sets the estimated prediction errors are close to the actual prediction errors for samples within the calibration range, while samples outside the calibration range must be background corrected before quantification of the prediction error.
    Additional Material: 10 Ill.
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  • 27
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 189-198 
    ISSN: 0886-9383
    Keywords: Robust regression ; Partial least squares ; QSAR ; Perturbation study ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A robust partial least squares (PLS) regression algorithm is developed. This is achieved by substitution of the univariate regression steps in the iterative PLS2 algorithm by a robust alternative. The angle between loading vectors from both perturbed and unperturbed solutions is used as a measure of robustness. By means of a perturbation study on a structure-activity data set, it is demonstrated that the stability of the robust method is superior to standard PLS.
    Additional Material: 4 Ill.
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  • 28
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0886-9383
    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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  • 29
    ISSN: 0886-9383
    Keywords: Principal factor analysis ; Factor analysis ; Eigenvalue analysis ; Multivariate analysis ; Weighted factor analysis ; Procrustean analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two approximate methods for weighted principal components analysis (WPCA) were devised and tested in numerical experiments using either empirical variances (obtained from replicated data) or assumed variances (derived from unreplicated data). In the first (‘spherical’) approximation each data vector was assigned a weight proportional to the geometrical mean of its variances in all dimensions. The arithmetical mean of variances was used instead in the other approximation. Both the numerical experiments with artificial data containing random errors of various kinds (constant, proportional, constant plus proportional, Poisson) and the analysis of two sets of Raman spectra clearly indicated the necessity of introducing statistical weights. The spherical approximation was found to be slightly better than the arithmetical one. The application of statistical weighting was found to improve the performance of PCA in estimation problems.
    Additional Material: 3 Ill.
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  • 30
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    ISSN: 0886-9383
    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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  • 31
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Chemometrics 6 (1992), S. 357-357 
    ISSN: 0886-9383
    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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  • 32
    ISSN: 0886-9383
    Keywords: Derivatization reaction ; Factorial design ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A number of nucleophiles have been successfully identified and quantified using the Kröhnke reaction with 2,3-diphenyl derivatives of quinolizinium salts. Optimization of the reaction conditions by means of a mathematical model involving analysis of the response surface has led to a better understanding of the factors exerting an influence on the above reaction.The parameters chosen were temperature, reaction time, base concentration, water concentration and nucleophile concentration. The reaction was developed in polar aprotic solvents (acetone, acetonitrile). To facilitate the nucleophilic attack, the presence of an organic base (triethylamine) was necessary, although concentrations in excess of 0·15M did not alter the development of the reaction. Since pharmaceutical solutions are often aqueous, the influence of water on the reaction was studied. Low water volumes have no significant influence on the opening of the quinolizinium ring by the nucleophilic reagent. However, when the water proportion exceeded that of the organic solvent, the fluorescence intensity was lower than expected. Development of the fluorescent reaction product was first detected 5 min after the reaction started. The fluorescence intensity reached its optimum value after 138 min.
    Additional Material: 2 Ill.
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  • 33
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0935-6304
    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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  • 34
    ISSN: 0935-6304
    Keywords: Splitless injection of large volumes ; Carrier gas supply ; Septum purge outlet ; Packed vaporizing chamber ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The classical vaporizing injector has been modified for splitless injection of large volumes: during solvent evaporation in the packed vaporizing chamber, the carrier gas supply is interrupted and the septum purge outlet fully opened. This prevents vapors penetrating the gas regulation system and keeps the pressure increase in the injector to a minimum.
    Additional Material: 3 Ill.
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  • 35
    ISSN: 0935-6304
    Keywords: SFE ; Metering valve ; Solid phase extraction (SPE) column ; Sorbent trapping ; Nitrobenzamide ; Antimicrobial drugs ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A novel integral restrictor-collector has been designed for use with a conventional supercritical fluid extraction (SFE) apparatus. The assembly reduces the path length between a micrometering valve and collector (a solid phase extraction (SPE) column), obviating the need for the complicated tubing and connectors usually associated with such devices. Also described is a heating-block assembly which encases the micrometering valve and provides uniform heating of the valve during extraction.The valve-SPE column assembly was part of a system used to perform the first reported SFE multi-residue drug recovery from fortified liver. Extractions used carbon dioxide pressurized to 690 bar as the supercritical fluid. Flow rates of expanded gas through the SPE columns were 3-4 L/min with concomitant quantitative trapping of the analytes on the sorbent bed. After SFE the three nitrobenzamide antimicrobial drug residues from the liver were eluted from the SPE columns by off-line analysis. The results demonstrated that losses of trace level analytes in tissue may be significantly reduced by including an integral metering valve-collector assembly as part of the SFE apparatus.
    Additional Material: 3 Ill.
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  • 36
    ISSN: 0935-6304
    Keywords: Pyrolysis-capillary GC ; Quantitative analysis ; Detection limit ; Ultra-thin layer poly(methyl methacrylate) ; Poly(ethylene terephthalate) ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The determination of nanometer thick layers of poly(methyl methacrylate) coated on to the surface of poly(ethylene terephthalate) film has been investigated by high resolution pyrolysis gas chromatography without sample pretreatment or modification of the instrumentation used. A good linear relationship was observed between the quantity of the characteristic pyrolysate and the thickness of the poly(methyl methacrylate) layer; the detection limit was sufficient to enable the quantitation of poly(methyl methacrylate)-to-poly(ethylene terephthalate) film thickness ratios of 1:20000 in composite materials.
    Additional Material: 2 Ill.
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  • 37
    ISSN: 0935-6304
    Keywords: HPLC ; Ion exchange ; Volatile mobile phases ; Nucleotides ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 38
    ISSN: 0935-6304
    Keywords: Capillary GC ; Capillary column sampling ; Aqueous samples ; PAHs ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 39
    ISSN: 0935-6304
    Keywords: Micro HPLC ; Methotrexate ; Clinical analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 40
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0935-6304
    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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  • 41
    ISSN: 0935-6304
    Keywords: Gas liquid chromatography, GLC ; Cold on-column injection ; Fatty acid methyl esters, FAME ; Anhydrous milk fat ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 42
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0935-6304
    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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  • 43
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0935-6304
    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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  • 44
    ISSN: 0935-6304
    Keywords: Microcolumn LC ; Enantiomeric resolution ; Chiral mobile phase additive ; γ-Cyclodextrin ; Dansyl derivatives ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dansyl derivatives of racemic phenylalanine and its analogs have been resolved by microcolumn liquid chromatography with γ-cyclodextrin as mobile phase additive. The enantioselectivity of the system was influenced by the concentrations of both γ-cyclodextrin and acetonitrile in the mobile phase. Enantiomers of phenylalanine, phenylglycine, and tyrosine were resolved by isocratic elution in a single chromatographic run.
    Additional Material: 7 Ill.
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  • 45
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0935-6304
    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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  • 46
    ISSN: 0935-6304
    Keywords: Electrolytic conductivity detection ; Nitrogen-mode optimization ; Open tubular columns ; Food contaminants ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The combination of open tubular column gas chromatography with electrolytic conductivity detection has been evaluated for the determination of nitrogen-containing pesticide residues in food extracts. Optimization of the column position at the column-detector interface was crucial to the successful operation of the detector. The signal-to-noise ratio and response stability of the detector are greatly influenced by the composition of the electrolyte solvent. Large volume splitless injections using retention gaps and optimized detector operating conditions enabled pesticide residues in food extracts to be determined at sub parts-per-million levels. Although the electrolytic conductivity detector is less sensitive than the thermionic ionization detector, its greater nitrogen selectivity can he crucial to the determination of nitrogen-containing contaminants in food extracts, particularly in complex mixtures where phosphorus-containing contaminants or matrix compounds are also present.
    Additional Material: 4 Ill.
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  • 47
    ISSN: 0935-6304
    Keywords: Linear temperature programmed retention indices ; Gasoline range hydrocarbons ; Chlorinated hydrocarbons ; Effect of column pressure on retention index ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper describes the experimentally determined linear temperature programmed gas chromatographic retention behavior of hundreds of gasoline range hydrocarbons and chlorinated hydrocarbons on a cross-linked 100% polydimethylsiloxane stationary phase. The retention indices of additional compounds which were not available as pure standards were measured in a synthetic gasoline after they had been positively identified by matching mass and infrared spectra.The experimentally determined retention information has been used to estimate the retention indices of additional compounds by extrapolation or interpolation of plots of carbon number against retention index of homologs.Isothermally determined Kovats retention indices of compounds measured on 100 % polydimethylsiloxane have been taken from the literature and converted to linear temperature programmed retention indices using the method of Guan et al [11]. For many of these compounds, an experimentally determined linear temperature programmed retention index was measured: agreement between experimental and converted values was excellent.In total, retention indices are presented for 480 compounds, including all possible alkylbenzenes containing ten or fewer carbon atoms, and over 150 monoenes and dienes. The effect of column pressure and the average linear velocity of the helium carrier gas on retention index and order of elution is described and discussed.
    Additional Material: 2 Ill.
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  • 48
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0935-6304
    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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  • 49
    ISSN: 0935-6304
    Keywords: Electrochromatography ; Chirasil-Dex coated capillaries ; Cyclodextrin stationary phase ; Enantiomer separation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 50
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0935-6304
    Keywords: Capillary electrophoresis ; Chemiluminescence ; Luminol ; Photon counting ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
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  • 51
    ISSN: 0935-6304
    Keywords: Press-fit connectors ; Temperature- and pressure-stable connectors ; Epoxy resin glue ; Metal to fused silica connections ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 52
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Press fit connectors and splitters ; Re-use ; Cleaning ; 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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  • 53
    ISSN: 0935-6304
    Keywords: HPLC ; MECC ; Plant extracts ; Flavonol aglycones ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 54
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0935-6304
    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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  • 55
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0935-6304
    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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  • 56
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0935-6304
    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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  • 57
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0935-6304
    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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  • 58
    ISSN: 0935-6304
    Keywords: Static SFE ; Dynamic SFE ; Aqueous matrixes ; Organic bases ; Nitrogenous bases ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The feasibility of using supercritical carbon dioxide for both static and dynamic extraction of organic bases from an aqueous matrix has been investigated. It appears that the greater the lipophilic portion of the molecule the more readily is the base extracted: triprolidine, sulfamethazine and caffeine were extracted whereas picolinic acid, succinonitrile, and nicotine were not.
    Additional Material: 3 Ill.
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  • 59
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Three-way press-fit device ; Cold on-column injection ; Solvent split ; Early solvent vapor exit ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In a previous paper we described the possibilities of cold on-column - sample split injection achieved by means of an inexpensive and simple three way press-fit device [1]. The same arrangement is proposed here for cold on-column - solvent split injection in which specific elimination of the solvent, without loss of any other sample components, is achieved by opening the splitting tube (or better, in this case, the early solvent vapor exit) during solvent elution, and then closing it during elution of the sample's other components.Discrimination between solvent and other sample components is achieved by means of a retention gap, a retaining precolumn, and an early vapor exit.The technique enables both selective enrichment of a sample, in order to record satisfactory mass and infrared spectra of minor components, and injection of large volumes (up to 100 μl) of dilute solutions which cannot be concentrated because of component volatility. Details of the assembly and tuning the system are given, together with some examples.
    Additional Material: 3 Ill.
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  • 60
    ISSN: 0935-6304
    Keywords: Halogenated diphenyl ethers ; Nitrated diphenyl ethers ; Fused silica open tubular column ; Dual-column dual-detector GC ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nineteen halogenated and/or nitrated diphenyl ethers (currently listed in EPA Method 8111) have been separated on a DB-5/ DB-1701 column pair connected to an inlet splitter and separate electron capture detectors. Retention times are included for 10 additional compounds evaluated for their suitability as internal standards or surrogate compounds for incorporation into Method 8111. Method reproducibility and linearity are discussed, and results are presented for extracts of two real samples spiked with the 19 diphenyl ethers and analyzed using the dual-column dual-detector arrangement.
    Additional Material: 3 Ill.
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  • 61
    ISSN: 0935-6304
    Keywords: Honey ; Free amino acids ; Capillary gas chromatography ; Heptafluorobutyryl isobutyl esters ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The chemical analysis of honey tends to concentrate on factors related to its state of preservation, e.g. HMF, diastase activity, and water content. Although there is no characteristic of honey officially regarded as suitable for certification of its botanical origin, literature is available in which several of the “minor” components of honey, such as flavors, di- and trisaccharides, and free amino acids, have been used to certify the botanical origin of the product.In this paper, six kinds of honey from different botanical sources (acacia, citrus fruit, chestnut-tree, rhododendron, rosemary, and lime-tree) were analyzed by capillary gas chromatography, and the data obtained evaluated statistically to determine whether the amino acid profile could be used to verify the botanical source of the material.The results have shown that the presence of amino acids such as arginine, tryptophan, and cystine is characteristic of a particular kind of honey, and that others, such as proline, asparagine, lysine, and methionine, can be used for discrimination if quantitative data is available about the levels of the compounds present.Evaluation of optimum split ratio for amino acid determination, and problems concerning the derivatization process, are also discussed.
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  • 62
    ISSN: 0935-6304
    Keywords: Coupled LC-GC-MS ; Loop interface ; Concurrent cosolvent evaporation ; Micro-LC ; Donor-acceptor complexes ; Fossil fuels ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A multidimensional LC-GC-MS system was developed and used to analyze complex fossil-fuel samples. The electron-acceptor stationary phase, 5 μm 2,4-dinitrophenylmercaptopropylsilica, was packed into a 0.32-mm × 350-mm microcapillary liquid chromatography (μLC) column. Aromatic fractions eluted from the μLC system at 12 μL/min and were diverted to the gas chromatograph mass spectrometer (GC-MS) by a ten-port switching valve with 50 and 7