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  • 1
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In vitro studies in our laboratory have indicated that murine hemopoietic progenitor cell (HPC) lines, irrespective of their differentiation stage, synthesize and accumulate in the cell membrane a unique species of chondroitin sulfate proteoglycan (CS-PG). It has been postulated that CS-PG participates in HPC adhesion to pericellular stromal fibronectin by interacting with its heparin-promoting binding region. To further support this contention, we first attempted to modify CS-PG synthesis in HPC by the use of chlorate and p-nitrophenyl (β-D-xyloside), which inhibit sulfation and glycosaminoglycan (GAG) addition in proteoglycans, respectively. We then studied the effect that these modifications may have in the adhesive capacity of HPC to interact with fibronectin and its cell- and heparin-promoting binding chymotryptic fragments. Treatment with chlorate which resulted in a decreased sulfation of membrane-associated 35 S-labeled CS-PG, as judged by ion exchange chromatography, did not affect HPC adhesion to fibronectin or its fragments. However, β-xyloside treatment which reduces the abundance of membrane-associated CS-PG, as evidenced by molecular sieve chromatography, produced a major and specific decrease in HPC adhesion to the heparin-promoting binding fragment of fibronectin. These results indicate that CS-PG are involved in HPC interaction with fibronectin, in a mode that seems to be dependent on the differentiation stage of HPC. © 1994 wiley-Liss, Inc.
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 164 (1995), S. 315-323 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The integrins are a class of adhesion molecules which have been implicated in the homing of hemopoietic stem cells and in their restriction within the bone marrow. Integrins function as mediators of cell-extracellular matrix (ECM) interactions and also of cell-cell interactions. They are unique membrane receptors which are capable of activation, change in affinity, and change in expression. Because of their broad potential for modulation we examined the effect of a cytokine growth factor which is present constitutively in the marrow, interleukin 3 (IL3), on integrin-mediated adherence of hemopoietic progenitor cells to the matrix component fibronectin (FN). The multipotential murine cell line B6Sut and the committed granulocyte progenitor cell line FDCP-1 were used. Both of these cell lines have been shown to bind to FN-coated dishes and to dishes coated with the 120 kDa and 40 kDa chymotryptic fragments of FN. It was found that after a brief withdrawal of IL3 the cells lost 80% adherence to the 120 kDa FN fragment containing the RGD cell binding site. This loss of binding was not related to a loss of viability, appeared unrelated to the growth/survival activity of IL3, and was quickly reversible by readdition of the growth factor. Adhesion of these cells to the RGD site was likely mediated by α5b̃1 integrin which was identified in the cell membrane of both cell lines, but present in low copy number in B6Sut cells. Two antibodies against the external and internal domains of α5 and one antibody against b̃1 were used to study expression of the integrin. By flow cytometry the expression of α5 was found to decrease in both cell lines by 4 h in the absence of IL3. The relative mean fluorescence intensity for B6Sut cells decreased from 1.0 (control cells always in the presence of IL3) to 0.6 over 4 h, and for FDCP-1 cells the decrement was from 1.0 to 0.8. The loss of RGD-mediated adhesion in the absence of IL3 appeared to proceed through this decrement in expression of the integrin; a loss of affinity of the receptor for its substrate was not detected. The general modulation of integrin activity by growth factors is of great interest because of its potential negative impact on the endothelium in cytokine-treated patients, and also because of its potential positive impact on engraftment during clinical bone marrow transplantation. © 1995 Wiley-Liss, Inc.
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Cell Biochemistry and Function 7 (1989), S. 293-300 
    ISSN: 0263-6484
    Keywords: Proteoglycans ; Hyaluronic acid ; Testicular cells ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Long-term cultures of somatic testicular cells derived from immature and pubertal rats were used to study the synthesis of proteoglycans (PG) and hyaluronic acid (HA). Labelled PG and HA in the culture medium, membrane-associated and intracellular pools were characterized by gel fitration, ion exchange chromatography and selected enzymatic and chemical treatments. Somatic cells synthesize a PG containing both heparan and chondroitin/dermatan sulfate (CS/DS) chains and a PG containing only CS/DS chains. No major qualitative changes in the type of PG were observed in cells derived from immature and pubertal animals. However, significant age-dependent differences in the cell distribution pattern of PG and HA were determined. This may have implications in the regulation of spermatogenesis.
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Cell Biochemistry and Function 9 (1991), S. 63-67 
    ISSN: 0263-6484
    Keywords: Collagen ; extracellular matrix ; testicular cells ; long-term culture ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The synthesis, distribution and types of collagen produced by somatic testicular cells in culture was studied. To investigate whether changes in collagen synthesis correlate with the age of the animal, cultures derived from immature and pubertal rats were established. Immature rats synthesize 40 per cent more collagen than pubertal rats. Both groups of animals synthesize procollagen types I and III. Pro-collagen type I is present in the culture medium as well as in the cell fraction, while type III is only detected in the culture medium. In the transition from immature to pubertal rat, the ratio of procollagen type III to procollagen type I diminishes from 5·7 to 1·7. These results indicate that the synthesis, distribution and molecular characteristics of interstitial collagens changes with the age of the animal. Since, the content of other extracellular matrix components such as proteoglycans and collagen type IV also varies with age, we postulate that the composition of the extracellular matrix in the testes is not constant but changes with sexual development.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Electrophoresis 15 (1994), S. 240-243 
    ISSN: 0173-0835
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Capillary zone electrophoresis was used to analyze some drugs illegally used in sports. The spectroscopic characteristics and electrophoresis migration parameters of diuretics, narcotics-analgesics and β-blockers were established. Analytical figures of merit including parameters on the precision of migration and limits of detection are discussed. Results for the separation of drugs of different doping families are discussed. An analysis of urine from a patient receiving daily dosis of atenolol is presented.
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  • 6
    ISSN: 0044-8249
    Keywords: Cyclodextrine ; Diffusion ; H/D-Austausch ; Festkörperstrukturen ; Raman-Spektroskopie ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 50 (1992), S. 21-25 
    ISSN: 0730-2312
    Keywords: extracellular matrix ; chondroitin sulfate proteoglycan ; mixed proteoglycan ; membrane-associated proteoglycan ; collagen ; testicular cells ; Sertoli cells ; synthesis of proteoglycans ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Sertoli cells in culture produce two isoforms of proteoglycans which are found in the culture medium and associated with the cell membrane. The amount of both types of proteoglycans increased when Sertoli cells were plated on type 1 collagen-coated dishes as compared to uncoated dishes. The effect is due to an increase in the synthesis of proteoglycans rather than a diminished rate of degradation of these molecules. The collagen substrate also affects the distribution of these macromolecules; an increase in the amount of membrane-associated proteoglycans occurs at the expense of the proteoglycans released to the culture medium. © 1992 Wiley-Liss, Inc.
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  • 8
    ISSN: 1040-0397
    Keywords: Iron ; Seawater ; Adsorptive stripping voltammetry ; Speciation ; 1-Nitroso-2-napthol ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A fast adsorptive stripping voltammetric procedure for the determination of ultratrace amounts of iron in unpurged oceanic waters is reported. The method is based on that developed by van den Berg et al. [l]. It was modified to increase the sensitivity, to measure in the presence of oxygen and to reduce drastically the analysis time at the ultratrace level (pM). The scan rate, pH and concentrations of reagents were optimized to avoid interferences using background correction. The catalytic effect of the hydrogen peroxide was not found using high scan rate. The instability of the peak was related to colloidal iron. Acidified or heated samples showed stable peaks. The method is insensitive to the turbulence of the solution during the scan. The reproducibility (±40 pM) and detection limits (120 pM) of the method were calculated using 60s deposition time and oceanic waters (600pM). The detection limit can be lowered to 70 pM using 3 min accumulation.
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  • 9
    ISSN: 0570-0833
    Keywords: cyclodextrins ; diffusion ; H/D exchange ; Raman spectroscopy ; solid-state structures ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
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  • 10
    ISSN: 0749-1581
    Keywords: NMR ; 1H-NMR ; NOESY ; TOCSY ; Desulfovibrio sp. ; ferredoxins ; [3Fe-4S] and [4Fe-4S] clusters ; 2D NMR ; iron-sulfur clusters ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1D and 2D 1H NMR studies are reported on the oxidized and reduced [4Fe-4S] cluster of Desulfovibrio gigas ferredoxin I (Fdl). Several low-field contact shifted resonances (fast relaxing) are assigned to β-CH2 and α-CH coordinated cysteinyl residues. NOESY patterns (supported by 1D NOE experiments) resolves four pairs of geminal β-CH2 protons at low-field. The cluster ligands are assigned non-specifically to Cys8, Cys11, Cys14 and Cys50, based on the X-ray structural analysis available for the oligomeric form, FdII, that contains a single [3Fe-4S] cluster. It was indicated in this case that Cys11 is not bound to the trinuclear cluster but is tilted towards the solvent. The presence of four pairs of geminal β-CH2 protons for FdI unambiguously proves the occupancy of the fourth site of the [3Fe-4S] complex and implies the coordination of the Cys11 at the cluster. Analysis of the oxidized form of FdII, using the same methodology as described for FdI, supports the presence of three cysteinyl ligands in the [3Fe-4S] core. Further, the combined use of the X-ray coordinates enables the specific assignment of the three cysteinyl ligands of the cluster, extending a previous assignment of Cys50. In addition, very broad resonances were detected for the reduced form of FdII in the low-field region around 200 ppm and in the high field region around -80 ppm.
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