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  • Articles: DFG German National Licenses  (9)
  • Biochemistry and Biotechnology  (4)
  • Key words Smooth muscle  (3)
  • Column liquid chromatography  (2)
  • 1
    ISSN: 1432-2013
    Keywords: Key words Smooth muscle ; Cell volume ; Chloride current
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The characteristics of volume-sensitive chloride current (I Cl) induced by osmotic cell swelling were studied using the whole-cell patch-clamp technique and cell diameters of antral circular guinea-pig myocytes were simultaneously measured under isosmotic and hyposmotic conditions by using a video image analysis system. At –60 mV, osmotic cell swelling (200 mosmol/l) activated a sustained inward current. Instantaneous current/voltage (I-V) relations obtained by step voltage pulses showed an outward rectification. At potentials above +40 mV, the current exhibited time-dependent decay. The outward current amplitude was decreased and the reversal potential was shifted to more positive potentials by replacement of external Cl– with gluconate–, while the current amplitude and the I/V relation were not affected by replacing extracellular Na+ with N-methyl-D-glucamine. The anion permeability sequence of the swelling-induced current was I– (1.80) 〉 Br– (1.31) 〉 Cl– (1) 〉 F– (0.85) 〉 gluconate– (0.18). The I Cl was effectively inhibited by the Cl– channel blockers, 4,4′-diisothiocyanatostilbene-2,2’-disulphonic acid (DIDS, 100 μM), and niflumic acid (10 μM). DIDS suppressed outward current more effectively than inward current. Also, the I Cl was dose-dependently inhibited by arachidonic acid, an unsaturated fatty acid and also inhibited by other unsaturated fatty acids (linoleic acid and oleic acid) but not by stearic acid, a saturated fatty acid. The inhibitory effect of arachidonic acid on I Cl was not prevented by indomethacin, a cyclo-oxygenase inhibitor and chelerythrine, a protein kinase C inhibitor. Under whole-cell patch-clamp conditions, the cell diameter was continuously measured using video image analysis, which reflects the change in cell volume. A hyposmotic-stimulation-induced increase of cell diameter was followed by I Cl activation. In intact single gastric myocytes, relatively severe hyposmotic (176 mosmol/l) superfusing solution increased the cell diameter and the pretreatment with DIDS or with niflumic acid significantly potentiated the above effect of hyposmotic superfusion. These results suggest that volume-sensitive outwardly rectifying chloride current (I Cl) is present in guinea-pig gastric myocyte and the I Cl may play a role in smooth muscle cell volume regulation.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-2013
    Keywords: Key words Smooth muscle ; Nonselective cationic current ; Carbachol ; Myosin light chain kinase ; ML-7
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The effects of myosin light chain kinase inhibitors on muscarinic stimulation-activated nonselective cationic current (I CCh) in guinea-pig gastric antral myocytes were studied using the whole-cell patch-clamp technique. I CCh was induced by carbachol (CCh, 50 μM) at a holding potential of –30 mV or –60 mV. ML-7, a chemical inhibitor of myosin light chain kinase (MLCK), inhibited I CCh concentration dependently in a reversible manner (53 ± 8.6% at 1 μM, mean ± SE, n = 11). In addition, amplitudes of I CCh were only 37 ± 2.7% of the daily control values following the addition of a peptide inhibitor of MLCK to the pipette solution. On the other hand, ML-7 had an inhibitory effect on voltage-operated Ca2+ channel current. The peak value of Ba2+ current at 0 mV was reduced to 35 ± 7.4% (n = 9) by 3 μM of ML-7. As I CCh is known to have an intracellular Ca2+ dependence, we tried to exclude the possibility that ML-7 inhibited I CCh indirectly via suppression of Ca2+ current and the similar inhibitory effects of ML-7 on I CChwere confirmed under the following conditions: (1) clamp of membrane potential at –60 mV; (2) clamp of intracellular [Ca2+] to 1 μM by 10 mM BAPTA; (3) pre-inhibition of Ca2+ channel by verapamil. Different from the effects on I CCh, ML-7 barely inhibited the same cationic current induced by guanosine 5’-O-(3-thiotriphosphate) (GTP[γS], 0.2 mM) in the pipette solution. These results suggest that a Ca2+/calmodulin-MLCK-dependent pathway can modulate the activation of I CCh in guinea-pig gastric antral myocytes.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-2013
    Keywords: Key words Smooth muscle ; Nonselective cationic current ; Carbachol (CCh) ; Protein kinase C (PKC) ; Desensitization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The possibility of the protein kinase C (PKC) pathway being a mechanism underlying the desensitization of carbachol- (CCh-)activated nonselective cationic current (I CCh) was investigated in a study of guinea-pig gastric myocytes. Using the conventional whole-cell patch-clamp technique with symmetrical CsCl-rich solution in pipette and bath, I CCh was induced by bath application of 50 µM CCh. With 0.5 mM EGTA [ethyleneglycol-bis(β-aminoethyl ether)-N,N,N′,N′-tetraacetic acid] in the pipette solution (0.5 mM [EGTA]i), I CCh decayed spontaneously (desensitization of I CCh) to around 20% within 10 min. Desensitization of I CCh was significantly attenuated with 2 mM [EGTA]i. At a concentration of 20 µM OAG (1-oleoyl-2-acetyl-sn-glycerol), a PKC activator, inhibited I CCh at 0.5 mM [EGTA]i but far less at 2 mM [EGTA]i (18% and 81% of control, respectively). The same cationic current induced by intracellular guanosine-5′-O-(3-thiotriphosphate) (GTP[γ-S]) was not inhibited by OAG with 0.5 mM [EGTA]i. The pretreatment of gastric myocytes with PKC inhibitors, either 1 µM chelerythrine or 1 µM peptide inhibitor, attenuated the desensitization of I CCh. [Ca2+]i was also measured by single cell microfluorometry using fura-2. Under CCh stimulation with 2 mM [EGTA]i, [Ca2+]i did not increase above 100 nM while it increased to around 260 nM with 0.5 mM [EGTA]i. These results suggest that the desensitization of I CCh is partly due to the Ca2+-dependent PKC pathway in guinea-pig gastric myocytes.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Column-switching ; Parathion, and metabolites in serum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new high-performance liquid chromatographic method with column-switching has been developed for the simultaneous determination of parathion and its metabolites such asp-nitrophenol and paraoxon in serum. Serum samples were injected onto a precolumn packed with LiChroprep RP-8 after simple dilution with 20% phosphoric acid. Polar plasma components were washed with 0.02 M phosphate buffer (pH 3.0). After valve switching, the concentrated compounds were eluted in back-flush mode and separated on a Ultracarb ODS 30 column with a gradient of acetonitrile −0.01 M phosphate buffer (pH 3.0) as mobile phase. The method showed excellent precision, accuracy and speed with detection limit of 0.1 μg mL−1. Total analysis time per sample was 〈40 min and coefficients of variation for intra-and inter-assay were 〈4.5%.
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  • 5
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Microbore columns ; Column-switching ; Myristicin ; Serum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A microbore high-performance liquid chromatographic method with column-switching was developed for the analysis of myristicin from rat serum without prepurification. Deproteinization, fractionation, concentration and separation of analyte were carried out by appropriate switching of columns and using solvent mixtures. The method showed excellent precision, accuracy and speed with a detection limit of 10 ng mL−1 from 25 μL of serum. The total analysis time per sample was 25 min and the coefficients of variation for intra- and inter-assay were less than 1.8%.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 42 (1993), S. 260-265 
    ISSN: 0006-3592
    Keywords: fouling ; ultrafiltration ; protein aggregates ; field emission scanning electron microscopy (FESEM) ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The factors contributing to protein aggregation in albumin ultrafiltration were investigated as a function of operation conditions. The nature of protein deposits was examined by electron microscopy. Protein aggregation appears to occur as a result of rapid supersaturation of protein molecules and high solvent velocity (shear) in the concentrated layer near the membrane surface. The shear occurring in the solvent flow on the membrane surface probably unfolds protein molecules and thus promotes flocculation due to collision between particles. © 1993 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 47 (1995), S. 174-180 
    ISSN: 0006-3592
    Keywords: ultrafiltration membranes ; protein fouling ; BET measurements ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Membrane morphology is compared to protein depostion under passive adsorption and ultrafiltration conditions. Solute resistance of protein deposits for membranes of varying roughness, structure, and permeability can vary dramatically with operating conditions. Using Brunauer-Emmett-Teller adsorption isotherm (BET), study of the internal area and accessibility of several uttrafiltration membranes to protein deposition allows better understanding of the fouling mechanisms and interpretation of adsorbed protein quantities. © 1995 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 27 (1985), S. 316-320 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Studies were conducted to establish optimal conditions for the acid hydrolysis of sweet potato for maximal ethanol yield. The starch contents of two sweet potato cultivars (Georgia Red and TG-4), based on fresh weight, were 21.1 ± 0.6% and 27.5 ± 1.6%, respectively. The results of acid hydrolysis experiments showed the following: (1) both hydrolysis rate and hydroxymethylfurfural (HMF) concentration were a function of HCL concentration, temperature, and time; (2) the reducing sugars were rapidly formed with elevated concentrations of HCl and temperature, but also destroyed quickly; and (3) HMF concentration increased significantly with the concentration of HCl, temperature, and hydrolysis time.Maximum reducing sugar value of 84.2 DE and 0.056% HMF (based on wet weight) was achieved after heating 8% SPS for 15 min in 1N HCl at 110°C. Degraded 8% SPS (1N HCl, 97°C for 20 min or 110°C for 10 min) was utilized as substrate for ethanol fermentation and 3.8% ethanol (v/v) was produced from 1400 mL fermented wort. This is equal to 41.6 g ethanol (200 proof) from 400 g of fresh sweet potato tuber (Georgia Red) or an ethanol yield potential of 431 gal of 200-proof ethanol/acre (from 500 bushel tubers/acre).
    Additional Material: 5 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 138-141 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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