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  • 1
    Electronic Resource
    Electronic Resource
    Characteristics of hydrocarbon uptake in cultures with two liquid phases (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 19 (1977), S. 9-25 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: In hydrocarbon fermentation, the efficiency of hydrocarbon uptake by cells ins one of the keys to the economical production of single-cell protein. This work is concerned with characterization of cultures with two liquid phases for understanding the hydrocarbon uptake process by cells. Batch cultivation of Candida lipolytica was carried out in shaking flasks and in a tower fermentor with motionless mixers. Micorscopic observation and cell and hydrocarbon concentration distribution in batch cultivation showed that some cells are attached to the large oil drops ad others are free from them. Interfacial tension between oil and water and Sauter mean drop size decreased as cultivation proceeded. On the basis of the experimental results, the process of hydrocarbon uptake by cells is discussed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260190103
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  • 2
    Electronic Resource
    Electronic Resource
    Hydrocarbon uptake in hydrocarbon fermentations (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 19 (1977), S. 1331-1349 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Candida lipolytica (strain ATCC 8662) was grown on a simple defined medium with n-hexadecane as the main carbon Source under batch fermentation conditions. The relative importance of the cells growing in the aqueous phase on the overall kinetics was studied. The effect of interfacial tension, unoccupied interfacial area, and pseudosolubility on the specific growth was also studied. Results are presented and discussed here.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260190907
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  • 3
    Electronic Resource
    Electronic Resource
    Oil drop size and gas hold-up in an oil-water airlift system with motionless mixers (1978)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 20 (1978), S. 487-501 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The degree of emulsification, measured as surface area of oil generated, was studied. The effect of interfacial tension, volume fraction of oil, and power per unit volume on the Sauter mean diameter of the oil drops was determined in an airlift system with motionless mixers. A mathematical expression to predict the Sauter mean diameter was developed using regression techniques. From this equation another equation, which will predict the surface area of oil in terms of the same variables, was derived. The effects of water air surface tension and power per unit volume on the gas hold-up were obtained using similar techniques. The results show that the interfacial tension and the surface tension are important variables when hydrocarbon fermentations are carried out in airlift systems.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260200403
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  • 4
    Electronic Resource
    Electronic Resource
    Continuous culture of Candida lipolytica on n-hexadecane (1978)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 20 (1978), S. 1833-1848 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Candida lipolytica was grown continuously on n-hexadecane as the main source of carbon. A transient continuous-culture experiment was also conducted to investigate hydrocarbon-limited growth; the hydrocarbon feed flow rate was stopped for several hours and then resumed at a reduced steady-state flow rate. Interfacial tension, Sauter mean diameter, pseudosolubility, fraction of cells in the aqueous phase, oil-phase volume fraction, and cell concentration were measured to characterize the system. The microorganisms appear to utilize both the submicron drops and the microscopic drops. The effects of interfacial tension, pseudosolubility, and unoccupied interfacial area on the kinetics of hydrocarbon fermentation are discussed here. A conceptual model for hydrocarbon uptake is presented and discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260201111
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  • 5
    Electronic Resource
    Electronic Resource
    Heat transfer simulation in solid substrate fermentation (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 35 (1990), S. 802-808 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A mathematical model was developed and tested to simulate the generation and transfer of heat in solid substrate fermentation (SSF). The experimental studies were realized in a 1-L static bioreactor packed with cassava wet meal and inoculated with Aspergillus niger. A simplified pseudohomogeneous monodimensional dynamic model was used for the energy balance. Kinetic equations taking into account biomass formation (logistic), sugar consumption (with maintenance), and carbon dioxide formation were used. Model verification was achieved by comparison of calculated and experimental temperatures. Heat transfer was evaluated by the estimation of Biot and Peclet heat dimensionless numbers 5-10 and 2550-2750, respectively. It was shown that conduction through the fermentation fixed bed was the main heat transfer resistance. This model intends to reach a better understanding of transport phenomena in SSF, a fact which could be used to evaluate various alternatives for temperature control of SSF, i.e., changing air flow rates and increasing water content. Dimensionless numbers could be used as scale-up criteria of large fermentors, since in those ratios are described the operating conditions, geometry, and size of the bioreactor. It could lead to improved solid reactor systems. The model can be used as a basis for automatic control of SSF for the production of valuable metabolites in static fermentors.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260350808
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  • 6
    Electronic Resource
    Electronic Resource
    Formation of Hydrido-η3-Allyl Complexes of IrIII by Sequential Olefinic C—H Bond Activation and C—C Coupling of Alkenyl and Olefin Ligands (1997)
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 3 (1997), S. 860-873 
    Details
    ISSN: 0947-6539
    Keywords: alkene complexes ; allyl complexes ; C-H activation ; C-C coupling ; iridium ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The bis(ethene) complex [Tp*Ir-(C2H4)2] (1*) (Tp* = tris(3,5-dimethyl-1-pyrazol-1-yl)hydroborato) undergoes thermal rearrangement to the hydrido-allyl complex [Tp*IrH(π3-C3H4Me)] (6*), through the intermediacy of the hydrido-vinyl complex [Tp*IrH(C2H3)(C2H4)] (2*). The overall conversion of 1* into 6* corresponds formally to the dimerisation of ethene by an unprecedented pathway that involves sequential C-H bond activation of a coordinated olefin molecule and C-C bond formation by coupling of the resulting vinyl and ethene moieties. Similar transformations have been observed for monosubstituted olefins like propene and 1-butene, while the internal alkene cis-2-butene experiences allylic activation of an sp3 C-H bond, which provides an alternative route to 6*. The extension of these investigations to the analogous complexes of the unsubstituted tris(pyrazolyl)hydroborato ligand Tp is also reported. Mechanistic studies on the formation of the C-C bond by coupling of the vinyl and the olefin ligands suggest the participation of a vinylidene complex (formed by α-H abstraction from the vinyl group), which then rearranges to an allene species. Evidence for the involvement of these and other key reaction intermediates is provided.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chem.19970030606
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  • 7
    Electronic Resource
    Electronic Resource
    Stereoselective cyclooxygenase inhibition in cellular models by the enantiomers of ketoprofen (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 589-595 
    Details
    ISSN: 0899-0042
    Keywords: NSAIDs ; enantioselectivity ; prostaglandin E2 ; thromboxane B2 ; HUVEC ; PMN ; keratinocytes ; P388D1 ; platelets ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The pharmacological activity of rac-ketoprofen and its enantiomers was investigated in vitro using different cellular models. The effect of these compounds on arachidonic acid metabolism was assessed by measuring the inhibition of prostanoid generation under the action of several agonists. Thus, we have evaluated the inhibition of (1) thromboxane B2 synthesis in rabbit platelets and human polymorphonuclear leukocytes (PMNs), (2) prostaglandin E2 synthesis in three cultured cells, namely human umbilical vein endothelial cells (HUVEC), human keratinocytes, and mouse macrophage-like P388D1 cells. The IC50 values found for (+)-(S)-ketoprofen were in the range between 0.1 nM and 0.8 μM, being slightly lower in all models than those found for rac-ketoprofen (0.4 nM-3 μM). On the other hand, (-)-(R)-ketoprofen showed inhibition of cyclooxygenase only at concentrations two or three orders of magnitude higher than those required for the (+)-(S) enantiomer. These results, obtained with cell types of relevance for inflammatory processes and with compounds of high optical purity, demonstrate that the prostanoid biosynthesis inhibition caused by the drug rac-ketoprofen is exclusively due to its dextrorotatory enantiomer. © 1993 Wiley-Liss, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050805
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  • 8
    Electronic Resource
    Electronic Resource
    Stereoselective metabolic pathways of ketoprofen in the rat: Incorporation into triacylglycerols and enantiomeric inversion (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 8 (1996), S. 163-172 
    Details
    ISSN: 0899-0042
    Keywords: arylpropionic acid ; ketoprofen ; enantiomer ; stereoselectivity ; Coenzyme A thioester ; hybrid triacylglycerols ; inversion ; adipose tissue ; hepatocytes ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The enantiomeric bioinversion of ketoprofen (KP) enantiomers and their incorporation into triacylglycerols were investigated in the rat (1) in vitro, using liver homogenates, subcellular fractions, and hepatocytes, and (2) in vivo, in different tissue samples after oral administration of the radiolabelled compounds. In liver homogenates or subcellular fractions, the enantiomer (S)-ketoprofen (S-KP) was recovered unchanged, whereas (R)-ketoprofen (R-KP) was partially converted into its Coenzyme A (CoA) thioester and inverted to S-KP. Both processes occurred mainly in the mitochondrial fraction. This supports the mechanism of inversion via stereoselective formation of CoA thioesters of R-KP, already described for other non-steroidal anti-inflammatory drugs. Incorporation into triacylglycerols was detected after incubation with intact hepatocytes in the presence of added glycerol. The process was stereoselective for R-KP vs. S-KP (covalently bound radioactivity 26,742 ± 4,665 dpm/106 cells vs. 6,644 ± 3,179 dpm/106 cells, respectively). However, no incorporation was found in liver samples after oral administration of either R-KP or S-KP. On the contrary, in adipose tissue samples a significant and stereoselective formation of hybrid triacylglycerols was observed: 11,076 ± 2,790 dpm.g-1 for R-KP vs. 660 ± 268 dpm.g-1 for S-KP. The incorporated R/S ratio, higher in adipose tissue (R/S = 17) than in hepatocytes (R/S = 4), indicates that fat may be the main tissue store for the xenobiotic R-KP in rats. © 1996 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Metabolic depletion inhibits the uptake of nontransferrin-bound iron by K562 cells (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 177 (1998), S. 585-592 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effect of metabolic inhibitors on nontransferrin bound iron transport by K562 cells was investigated. Incubation with 1 μM rotenone, 10 μM antimycin, or 0.5 mM 2,4-dinitrophenol effectively reduced ATP levels by ∼50%. Both the rate and extent of Fe+3 uptake were impaired in ATP-depleted cells, which display a reduced Vmax for uptake. K562 cell ferrireductase activity was also lowered by metabolic inhibitors, suggesting that the apparent energy requirements for transport reside in the reduction of Fe+3 to Fe+2. However, ATP depletion was found to inhibit the rate and extent of Fe+2 uptake as well. Thus, the transbilayer passage of Fe+2 and/or Fe+3 appears to be an energy-requiring process. These features possibly reflect properties of the transport mechanism associated with a recently identified K562 cell transport protein, called SFT for “Stimulator of Fe Transport,” since exogenous expression of its activity is also affected by ATP depletion. J Cell Physiol 177:585-592, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Tumor necrosis factor and interleukin 1 inhibit parathyroid hormone-responsive adenylate cyclase in clonal osteoblast-like cell by down-regulating parathyroid hormone receptors (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 153 (1992), S. 206-213 
    Details
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effects of the monokines tumor necrosis factor α (TNF) and interleukin 1 (IL 1) on parathyroid hormone (PTH)-responsive adenylate cyclase were examined in clonal rat osteosarcoma cells (UMR-106) with the osteoblast phenotype. Recombinant TNF and IL 1 incubated with UMR-106 cells for 48 hr each produced concentration-dependent inhibition of PTH-sensitive adeylate cyclase, with maximal inhibition of PTH response (40% for TNF. 24% for IL 1) occuring at 10-8 M of either monikine. Both monokines also decreased adenylate cyclase stimulation by the tumor-derived PTH-related Protein (PTHrP). In contrast, TNF and IL 1 had little or no inhibitory effect on receptor-mediated stimulation of adenylate cyclase by isoproterenol and nonreceptors-mediated enzyme activation by cholera toxin forskolin; both monokines increased prostaglandin E2 stimulation of adenylate cyclase. Binding of the radiodinated agonistt mono-[125I]-[Nle3, 18, Tyr34]bPTH-(1-34)NH2 to UMR-106 cells in the presence of increasing concentrations of unlabeled [Nle8,18, Tyr34]bPTH-(1-34)NH2 revealed a decline in PTH receptor density (Bmax) without change in receptor binding affinity (dissociation constant, Kd) after treatment with TNF or IL 1. Pertusis toxin increased PTH-sensitive adenylate cyclase activity but did not attenuate monokine-induced inhibiton of PTH response. In time course studies, brief (1hr) exposure of cells to TNF or IL 1 during early culture was sufficient to decrease PTH response but only after exposed cells were subsequently allowed to grow for prolonged periods. Inhibition of PTH response by monokines was blocked by cycloheximide. The results and indicate that TNF and IL 1 impair responsiveness to PTH (and PTHrP) by a time protein synthesis-dependent down-regulation of PTH receptors linked to adenylate cyclase. © 1992 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1041530125
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