Resting cultures

Pressmar, J., Brinkmeier, H., Seewald, M.J., Naumann, T., and Rudel, R., 1994, Intracellular Ca2+ concentrations are not elevated in resting cultured muscle from Duchenne (DMD) patients and in MDX mouse muscle fibres, Pflugers Arch, 426, pp 499-505. 

H37. Huang, Y.-P., Miescher, P. A., and Zubler, R. H. The interleukin-2 defect in vitro in systemic lupus erthematosus is reversible in rested cultured T cells. / Immunol. 137, 2545-2548 (1986). H38. Hume, D. A., and Denkins, Y. M. Activation of macrophages to express cytocidal activity correltes with inhibition of their responsiveness to macrophage colony-stimulating factor (CSF-1) Involvement of a pertussis toxin-sensitive reaction. Immunol. Cell. Biol. 67, 243-249... 

Because of the way that resting cultures, spore cultures, and immobilized cultures are set up for use in biotransformation, the number of cells per unit volume of such preparations can be adjusted by appropriate dilution to any required level. In each case the optimum number of cells per unit volume in such preparations will need to be established empirically for a particular biotransformation. 

An example illustrating both problems, and some suitable solutions, is provided by the Baeyer-Villiger mono-oxygenase-dependent biotransformation of bicyclo(3.2.0.)hept-2-en-6-one to synthetically useful lactones by a resting culture of the cyclopentanol-grown bacterium Pseudomonas sp. NCIMB 9872 (Figure 2.10). 

The biosynthesis of ochratoxin A was, therefore, reduced to a study of the origin of the isocoumarin acid, 7 this investigation was carried out by Steyn et al. (1970). Sodium [1- " C]acetate was added to resting cultures of A. ochraceus. On acid hydrolysis of the labeled ochratoxin A, the isocoumarin acid 7 was found to contain all the activity. Kuhn-Roth oxidation of compound 7 gave acetic acid which contained 20% of the total activity. Schmidt... 

The origin of the carboxy group at C(8) was established by Steyn et al. (1970) through addition of DL-[m /zj /- C]methionine to a resting culture of A. ochraceus. The resulting radioactive ochratoxin A was hydrolyzed and the isocoumarin acid, 7, was converted into the acid azide, 10. Schmidt decarboxylation of 10 yielded active carbon dioxide, whereas the amine (11) contained no activity. 

World production of unsaturated polyester resins in 1997 was of the order of 1.7 X 10 tonnes, with the USA accounting for about 45% and Western Europe 27%. Over 75% is used in reinforced plastics, with the rest being used for such diverse applications as car repair putties, cultured marble , wood substitution and surface coatings. The pattern of consumption in 1993 of reinforced polyesters in the USA was reported as ... 

This has been despite the fact that the UK has developed with a culture that is indifferent to engineering, the respectable professions being those such as law or medicine offering more money and prestige. This deeply rooted attitude was supported by an education system in which on the whole applied science - engineering - was not studied in schools or universities. This contrasts with the rest of world, where such studies were an important part of the curricula of many schools and universities as early as the eighteenth century. Engineering was not considered suitable for those with the ability to enter a university, where arts and sciences were studied. 

The culture can be used directly for the conversion of phenylpyruvic add to resting cells L-phenylalanine. Therefore, a batch process with resting cells can be carried out, with some glucose added for maintenance (fed-batch fermentation). Another approach is to harvest the cells from the fermentation broth and to use them in a separate bioreactor in higher concentrations than the ones obtained in the cell cultivation. An advantage of the last method can be that the concentration of compounds other than L-phenylalanine is lower, so that downstream processing may be cheaper. 

Research in this area advanced in the 1970 s as several groups reported the isolation of potent toxins from P. brevis cell cultures (2-7). To date, the structures of at least eight active neurotoxins have been elucidated (PbTx-1 through PbTx-8) (8). Early studies of toxic fractions indicated diverse pathophysiological effects in vivo as well as in a number of nerve and muscle tissue preparations (reviewed in 9-11). The site of action of two major brevetoxins, PbTx-2 and PbTx-3, has been shown to be the voltage-sensitive sodium channel (8,12). These compounds bind to a specific receptor site on the channel complex where they cause persistent activation, increased Na flux, and subsequent depolarization of excitable cells at resting... 

In 1995, HlV-1 latency was first documented in HIV-1-infected patients when ex vivo T cell cultures were found to contain a subpopulation of cells that produced infectious virions when stimulated with T cell activators (Chun et al. 1995 Finzi et al. 1997). Latently infected T cells are rare, to the order of one in a million resting... 

These results led us to reexamine the published work on nitrosation in the presence of bacteria (Table II) In two of the studies (, 10) the amount of NDMA formed is actually less than the amount that can be predicted from theoretical consideration of the uncatalyzed chemical reaction alone (15) In another study (12), the yield of NDMA is again slightly lower than the predicted chemical yield at the final pH (6 0) of the growing culture The work by Kunisaki and Hayashl (13), on the other hand, does indicate that resting cells of E. coli B catalyze... 

While no book on the subject could be exhaustive, The Bathhouse at Midnight does describe and assess all the literary sources of magic, witchcraft, astrology, alchemy, and divination from Kiev Rus and Imperial Russia, and to some extent Ukraine and Belorussia. Where possible, Ryan identifies the sources of the texts (usually Greek, Arabic, or West European) and makes parallels to other cultures, ranging from classical antiquity to Finnic. He finds that Russia shares most of its magic and divination with the rest of Europe... 

Initial scale-up of microbial biotransformation is conveniently run with multiple flasks without extensive reaction optimization. A typical flask fermentation is performed at 28 °C, 250 rpm with 100 mL culture in a 500 mL Erlenmeyer flask, although other settings will work fine too. Three parameters need to be investigated before scale-up the time for adding the substrate, the optimal substrate concentration and the time course of product formation. Optimization of other factors, such as medium composition and pH, growing cells versus resting cells [74], is helpful, if the timeline allows and if there is a sufficient amount of the substrate to support the screening. 

The thermophilic enzyme DszD from Paenibacillus All-2 has been cloned into E. coli and characterized [172], The sequence of this enzyme showed 30% similarity to the major flavin reductase of Vibrio fischeri. The optimum activity was reported to be at 45°C in resting cell cultures and 55°C in cell-free extracts. 

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