Unidentified factors

Schuetz JD, Connelly MC, Sun D, Pai-bir SG, Flynn PM, Srinivas RV et al. MRP4 A previously unidentified factor in resistance to nucleoside-based antiviral drugs. Nature Med 1999 5(9) 1048—1051. 

Lucerne is one of the most widely grown forage crops on a worldwide basis and is used commonly in livestock diets. It is a good source of many nutrients and in the past the inclusion of lucerne meal was considered to be essential in diets for a wide range of animals as a source of unidentified factors. Currently lucerne meal is used in poultry diets as a source of pigments to provide a yellow colour in egg yolks, shanks and skin (e.g. Karadas et al, 2006). 

It is more likely that p53 influences repair in a regulatory capacity. One link between p53 and NER was made with the observation that the p5 3-regulated Gadd45 binds to PCNA, a component of both replication and repair [206]. Overexpression of Gadd45 provided a small level of protection from cisplatin [207], whereas Gadd45 antisense DNA sensitized human colon carcinoma cells to cisplatin, an effect which was associated with a decrease in repair [201], It was hypothesized that the Gadd45 protein could interact directly with the repair proteins because it stimulated repair synthesis in nuclear extracts [206] however, this result could not be reproduced under a variety of experimental conditions [208][209], Thus, it seems likely that there are still some as yet unidentified factors which link p53 and the excision repair pathway. 

Catalytic activity varies tremendously among heme proteins, partly due to exposure/or accessibility of the hematin stmcture and partly due to other unidentified factors. 

Sewage Sludge Strain. The sludge strain PS of M. ruminantium is similar nutritionally to the rumen strain but is less exacting in its requirements and can be grown easily in a chemically defined medium—i.e., the medium shown in Table II but with 3.8 mM (NH4)2S04 added and with rumen fiuid and volatile acids other than acetate deleted. This strain does not require 2-methylbutyric acid, amino acids, or the unidentified factor required by the rumen strain. In fact, it biosynthesizes this growth factor. However, it does require acetate and ammonia. 

The authors acknowledge the excellent technical assistance of Melvin R. Crabill and Kenneth Holmer in various aspects of this work. Strain PS, M. ruminantium, was obtained through the courtesy of Paul H. Smith, University of Florida, Barry McBride kindly supplied hot 80% ethanol extracted-Dowex 50-treated extracts of strains MOH, PS and Methano-sarcina for assay of unidentified factor required by strain Ml. This research was supported in part by PHS research grant EC00289 and U.S. Department of Agriculture Hatch funds 35-331. 

Exactly which reaction predominates is presently unknown. All those listed may occur to some extent and may be dependent upon reaction temperature, removal of gaseous products through sparging, or other as yet unidentified factors. Plutonium... 

Kashin-Beck Disease, A type of severe arthritis is described in parts of China and neighboring areas of Russia where soil selenium is particularly low. However, trials of selenium supplementation were not conclusive and other unidentified factors may be present. 

Amino acid substitutions in these regions have been shown to affect PrP-res formation in scrapie-infected cells (Kaneko et al, 1997b). The authors of the study proposed the existence of an unidentified factor, protein X, to explain the inhibition of PrP-res formation by point mutations in these regions. However, it also seems possible that the mutations affect the direct binding and/or conversion of PrP to PrP . The ability of such mutants to inhibit PrP formation in trans may be due to an ability to bind wild-type PrP-res, and, without converting themselves, to block the binding and conversion of wild-type PrP (see Section VII, C) (Priola etal., 1994 Horiuchi et al, 2000). 

The vitamin B -group VII. Replacement of vitamin Bj for some microorganisms by -alanine and an unidentified factor from casein. J. biol. Chem. 158, 497 (1945). 

In conclusion, undifferentiated cell cultures of Papaver species do not produce morphinan alkaloids. On differentiation laticifers are formed this is probably an important factor for the production of morphinan alkaloids, but other, still unidentified, factors also play a role. On the other hand, differentiation is not necessary for the production of sanguinarine (see Section VI,F). 

Permeability coefficients may be affected by chemical properties other than log and MW. For example, steric interactions, limitations of MW as a representation of molecular size, and unidentified factors that cause some compounds to act as penetration enhancers may affect permeability coefficients but would not be conveyed entirely by log and MW. Equation 15.7 will not account for these additional influences on permeability coefficients. However, the error in Equation 15.8 may be reduced compared with Equation 15.7, because Equation 15.8 is based on the animal-to-human ratio of permeabihty values. Equation 15.7 implicitly assumes that permeability coefficients are affected by log and MW only, which is a more restrictive assumption than the assumption built into Equation 15.8 that all unexplored factors have quantitatively the same effect in all species. That is, with the same amount of data, analysis with Equation 15.8 is preferable to analysis with Equation 15.7 as long as these additional factors influence permeability coefficients the same way in both human and animal skins. 

Evidence for the Presence of Unidentified Factors Essential for Life... 

The extraction conditions used can affect the yield of PAs, their relative proportions, and the ratio of the tertiary alkaloid to PANO. For aU extraction methods higher proportions of PANOs are obtained by extracting at room temperature than by methods that involved heating. Prolonged Soxhlet extraction causes a marked loss of PAs and a decrease of the proportion of PANO. An unidentified factor present in the plant material is suspected of being responsible for this loss. The best yields are obtained by relatively short treatments with acidified water or methanol, or their mixtures, at elevated temperature. The choice between water and methanol can be influenced by the sample. Some starchy products can swell and form a gel in hot water but methanol extracts more chlorophyll from green plants and lipid from e.g., animal feed samples. 

The wax moth, Galleria mellonella, in addition to requiring fat in the diet, requires at least thiamine and nicotinic acid, and the rice moth, Gorcyra cephalonica requires thiamine, riboflavin, and pyridoxine in addition to unidentified factors. 

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