Butyrate, labelled

Figure 5. Fluorescence spectra of pyrene tagged novolac and free pyrene butyric acid (PBA) in diglyme. Spectra are labeled with percent of monomer units tagged. The pyrene concentration in solution is 1 x 10 bM, except in the inset where different pyrene concentrations are compared along with the spectra of a film containing the tagged polymer.

Attempts to label dangerous substances with either characteristic or outright unpleasant odors have not been successful with children, the primary victims of accidental poisonings by toxic household products. Children tolerate odors that adults find unpleasant, such as that of butyric acid. The range between the most pleasant and unpleasant odors is much narrower for children around 4years of age than for adults, and also much narrower than for taste stimuli. This means that olfactory cues are not suited to produce aversive responses in children (Engen, 1974b, Cain, 1978). 

Natural esters are widely used by the aroma and fragrance industries because of their fruity or floral taste/odor. Many of them are alkyl esters of formic, acetic, propionic, and butyric acids. The development of an efficient biotechnological process, compatible with the natural label for the products but offering costs comparable to the costs of chemical processes, has been achieved, representing the first application of gas/solid technology on an industrial scale [51]. 

The total yield of 201 was increased and the synthesis time reduced by extracting [nC]butyric acid from its lithium salt by dry 0.1% HCl/He gas mixture and carrying out its pyrolysis at 530 °C over glass beads (equation 104). The relative reactivity of 201 to primary, secondary and tertiary alcohols (equation 105a, b, c) has been found to be as 1 0.4 0.1, respectively. Several bioactive compounds have been labelled with [nC]propyl ketene, such as carbohydrate compounds193 and IV-butyl compounds, for instance /V- 11 C]butyryl THPO, 202, and some phorbol esters192, 203, 204 and 205. 

Labelling of Cells. For labelling experiments, Dulbecco s modified Eagle s medium was used, except it contained only 1% glucose. Cells were seeded at 1 to 2 x 10 > cells/75 cm2 flask in medium at 37° and allowed to attach for 20-24 hours. The medium was then replaced with fresh medium containing sodium butyrate,... 

Labelled Fucolipids. Figure 3 shows fluorograms which were obtained from cells labelled with DiG -fucose with and without butyrate treatment. Fucolipids were not found in fetal cells and, therefore, are not shown here. Figure 3A, track 2, shows fucolipid patterns of SW-480 cells without butyrate. Although... 

Labelled Neutral Glycolipids. Neutral glycolipids were labelled with -galactose. As was seen with the ganglioside, the butyrate affected the neutral glycolipid patterns but the most marked alterations appeared to be due to changes in the lipid moeities. 

When cells were cultured in labelled fucose or galactose in the presence or absence of butyrate, alterations in the labelled glycolipids were observed. Treatment of all of the cell lines with butyrate did not markedly affect the incorporation of l hJ galactose in ganglioside per milligram of cell protein. 

Gangliosides were labelled with galactose. In the fetal cell lines (FHS) and SKCO-1 there was no marked difference between treated and untreated cells. In HT-29, SW-480, and Sw-620 cell lines, the amounts of Gm3 appeared to remain the same, but the distribution of Gm3 components was affected by butyrate. These changes, might be due to alterations in the lipid moieties or, alternatively, there might be an acetylation Of a hydroxyl group in the carbohydrate moiety, since it has been shown that the butyrate increases the amount of acetylated histones. 

When HeLa cells were.cultured in medium supplemented with 5 mM sodium butyrate, their content of GM3 increased (Fig.2a). Increases varied from 3.5 to 5-fold depending on the experiment (4,8,12,13). When the butyrate was removed and the cells were cultured in normal medium for 24 h, the GM3 levels returned to those found in untreated cells (Fig. 2a). Similar results were observed when N-[acetyl-3H]-D-mannosamine, a precursor of sialic acid, was also included in the culture medium. In the butyrate-treated cells, radioactivity associated with GM3 increased 6.5-fold and 24 h after butyrate was removed, the amount of labeling returned to control values (Fig. 2b). We also were able to label the GM3 by means of a cell surface labeling technique. Control and butyrate-treated cells were exposed to 10 mM sodium periodate and the oxidized sialyl residues were reduced with NaBSfy. There was 5.5-fold more 3h associated with the GM3 recovered from the butyrate-... 

HeLa cells were cultured in medium containing N[acetyl-3H]-D-mannosamine (50 pCit mL) for 24 hr with (solid bars) and without (open bars) 5 mM sodium butyrate. In addition, butyrate-treated cells were cultured an additional 24 hr in fresh medium (without label and butyrate) (hatched bars). The cells were harvested and analyzed for GM3 content and radioactivity. (Data from Refs. 8, Vi.)... 

Exposure of HeLa cells to butyrate had no effect on the activity of GM3-sialidase when GM3 specifically labeled in the sialic acid residue was used as substrate (Fig. 3a). We were unable to detect any "ecto"-sialidase activity in either control or butyrate-treated cells (14) although others have postulated that such an enzyme is important in regulating plasma membrane gangliosides (15,16). In contrast, the activity of the specific sialyl transferase involved in GM3 biosynthesis increased over 20-fold following butyrate treatment (Fig. 3b). The effect was specific as activities of the other glycosphingolipid transferases that could be measured in HeLa cells were not altered in butyrate-treated cells (4,8,17). 

HeLa cells were cultured for 24 hr with (open bars) and without (closed bars) 5 mM sodium butyrate, harvested, and assayed for indicated enzyme activity. A GM3-sialidase activity assayed with GM3 specifically labeled with [,iC]- N-acetylneuraminic acid as substrate ("14JJ. B Sialyltrasferase activity assayed with CMP-[, acetylneuraminic acid and lactosylceramide as substrates, and synthesis of labeled GM3 determined (17). Data... 

Figure 5. Effect of labeled and unlabeled choleragen concentrations on n5I-choleragen binding to control and butyrate-treated HeLa cells...

The assembly of the carbon skeletons of these unusual hydrocarbons was first studied in Carpophilus freemani Dobson, through careful GC-MS and Nuclear Magnetic Resonance (NMR) studies of the incorporation of 2H or 13C-labeled precursors (Petroski et al., 1994). Assembly of the carbon skeleton of the aggregation pheromone of C. freemani, (2 , 4 , 6ii)-5-ethyl-3-methyl-2,4,6-nonatriene, involves initiation with acetate elongation with first propionate (to provide the methyl branch), then butyrate (to provide the ethyl branch) and chain termination with a second butyrate (Figure 6.7). At some point, loss of C02 from one of the butyrate units occurs to yield the appropriate hydrocarbon, but Petroski et al. (1994) were unable to determine which of the butyrate units loses its carboxyl group. Bartelt and Weisleder (1996) studied the biosynthesis of 15 additional methyl- and/or ethyl-branched, tri- and tetraenes in the related... 

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