Synthesis of 2'-deuterio and 3'-deuterio cytidine 5'-diphosphate

2'-2H- and 3'-2H-CDP were synthesized from 5'-MMT-3'-O-TBDMS and 2',5'-O-diTBDMS cytidine derivatives, respectively, by oxidation followed by acidic removal of 5'-protection, reduction with [NaBD(OAc)3] and finally displacement of a tosyl group by pyrophosphate.     

固定化酵母生物合成胞二磷酸胆碱(CDPC)

对固定化酵母生物合成胞二磷酸胆碱反应液浓度进行了研究。通过几组实验,找到了反应液中底物的最佳浓度;磷酸胆碱75μmol/mL,胞苷酸（CMP）10μmol/mL,葡萄糖400μmol/mL,硫酸镁和硫酸锰分别为10μmol/mL和1μmol/mL。可以不使用还原剂。     

Effect of cytidine diphosphate choline (CDP-choline) on ischemia-induced alterations of brain lipid in the gerbil

Brain ischemia was produced in gerbils (Meriones unguiculatus) by the bilateral ligation of the carotid arteries. Definite changes in the energy status of brain demonstrated that carotid occlusion was effective. Five minutes before ligation, an intraventricular injection of either saline or cytidine diphosphate choline (CDP-choline, 0.6 mol/brain, 3l) was given to groups of animals. Control animals, with and without CDP-choline, together with the ischemic groups, were decapitated directly into liquid nitrogen; 10 min after arterial ligation. Brain free fatty acids, neutral lipids and phospholipids, which were labeled in vivo by the intraventricular injection of [1-¹⁴C] arachidonic acid (0.4–0.6 Ci, 6–9 nmol) 2 hr prior to ligation, were extracted, purified, and separated by thin-layer chromatographic procedures. The CDP-choline treatment noticeably corrected the increase of total and individual fatty acids due to ischemia and the increase of their radioactivity content. The changes in neutral lipids, particularly in the diacyl glycerol fraction, were also corrected by the injection of the nucleotide. CDP-choline partially reversed the decrease of brain phosphatidylcholine and of its labeling, which was due to ischemia. All the data indicate that the prior injection of CDP-choline stimulates the choline phosphotransferase reaction of brain towards synthesis of phosphatidylcholine and prevents the release of free fatty acids, particularly of arachidonic acid, associated with ischemia.     

Effect of polyamines on synthesis and degradation of guanosine 5'-diphosphate 3'-diphosphate

The effect of polyamines on the in vitro and in vivo synthesis and degradation on guanosine 5'-diphosphate 3'-diphosphate (ppGpp) has been studied in Escherichia coli. The presence of 2 mM spermidine lowered the optimal Mg2+ concentration for ppGpp formation from 17 mM to 11 mM. The formation of ppGpp in the presence of 2 mM spermidine and 11 mM Mg2+ was about 15% greater than that in the presence of 17 mM Mg2+. At a concentration of less than 11 mM Mg2+, spermidine was found to stimulate ppGpp formation greatly. Putrescine did not cause any effect. When a polyamine-requiring mutant of E. coli (EWH319) was starved for an amino acid by the addition of valine, spermidine stimulated ppGpp formation. The degradation of ppGpp was not influenced significantly by polyamines.     

Effects of analogues of ethanolamine and choline on phospholipid metabolism in rat hepatocytes

1. Analogues of ethanolamine and choline were incubated with different labelled precursors of phospholipids and isolated hepatocytes and the effects on phospholipid synthesis were studied. 2. 2-Aminopropan-1-ol and 2-aminobutan-1-ol were the most efficient inhibitors of [(14)C]ethanolamine incorporation into phospholipids, whereas the incorporation of [(3)H]choline was inhibited most extensively by NN-diethylethanolamine and NN-dimethylethanolamine. 3. When the analogues were incubated with [(3)H]glycerol and hepatocytes, the appearance of (3)H in unnatural phospholipids indicated that they were incorporated, at least in part, via CDP-derivatives. The distribution of [(3)H]glycerol among molecular species of phospholipids containing 2-aminopropan-1-ol and 1-aminopropan-2-ol was the same as in phosphatidylethanolamine. In other phospholipid analogues the distribution of (3)H was more similar to that in phosphatidylcholine. 4. NN-Diethylethanolamine stimulated both the conversion of phosphatidylethanolamine into phosphatidylcholine and the incorporation of [Me-(14)C]methionine into phospholipids. Other N-alkyl- or NN-dialkyl-ethanolamines also stimulated [(14)C]methionine incorporation, but inhibited the conversion of phosphatidylethanolamine into phosphatidylcholine. This indicates that phosphatidyl-NN-diethylethanolamine is a poor methyl acceptor, in contrast with other N-alkylated phosphatidylethanolamines. 5. These results on the regulation of phospholipid metabolism in intact cells are discussed with respect to the possible control points. They also provide guidelines for future experiments on the manipulation of phospholipid polar-headgroup composition in primary cultures of hepatocytes.     

Effects of orally administered bovine lactoperoxidase on dextran sulfate sodium-induced colitis in mice

The effect of lactoperoxidase (LPO) on dextran sulfate sodium-induced colitis was examined in mice. After 9 d of colitis induction, weight loss, colon shortening, and the histological score were significantly suppressed in mice orally administered LPO (62.5 mg/body/d) as compared to a group administered bovine serum albumin. These results suggest that LPO exhibits anti-inflammatory effects in the gastrointestinal tract.     

Effects of cytidine 5'-diphosphocholine on plasma homocysteine levels in rat

We have investigated the effects of cytidine 5'-diphosphocholine (CDP-choline) on total plasma homocysteine concentration in male Sprague-Dawley rats of 2 months of age (young rats) or 15 months of age (old rats). Oral administration of 0.35 or 1 g/kg of CDP-choline to young rats significantly increased homocysteine, by 19 and 47%, respectively (P<0.05) in plasma obtained 25 min after treatment. This effect was transient for the administration of 0.35 g/kg and increased up to 64% (P<0.05) after 150 min for the administration of 1 g/kg. However, treatment through a supplemented diet resulting in an average daily intake of 0.35 g/kg of CDP-choline for up to 60 days did not significantly alter homocysteine concentration. Old rats showed a significantly (P<0.05) lower homocysteine level (25%) than control young animals, even after 60 days of treatment with the supplemented diet. Thus, when rats are used in experimental studies on the beneficial effects of CDP-choline, it has to be considered that administration of high doses of CDP-choline will not affect the plasma levels of the risk factor homocysteine as long as the compound is not administered as a single bolus.     

5-Caffeoylquinic acid and caffeic acid orally administered suppress P-selectin expression on mouse platelets

Caffeic acid and 5-caffeoylquinic acid are naturally occurring phenolic acid and its quinic acid ester found in plants. In this article, potential effects of 5-caffeoylquinic acid and caffeic acid on P-selectin expression were investigated due to its significant involvement in platelet activation. First, the effects of 5-caffeoylquinic acid and caffeic acid on cyclooxygenase (COX) enzymes were determined due to their profound involvement in regulating P-selectin expression on platelets. At the concentration of 0.05 microM, 5-caffeoylquinic acid and caffeic acid were both able to inhibit COX-I enzyme activity by 60% (P<.013) and 57% (P<.017), respectively. At the same concentration, 5-caffeoylquinic acid and caffeic acid were also able to inhibit COX-II enzyme activity by 59% (P<.012) and 56% (P<.015), respectively. As expected, 5-caffeoylquinic acid and caffeic acid were correspondingly able to inhibit P-selectin expression on the platelets by 33% (P<.011) and 35% (P<.018), at the concentration of 0.05 microM. In animal studies, 5-caffeoylquinic acid and caffeic acid orally administered to mice were detected as intact forms in the plasma. Also, P-selectin expression was respectively reduced by 21% (P<.016) and 44% (P<.019) in the plasma samples from mice orally administered 5-caffeoylquinic acid (400 microg per 30 g body weight) and caffeic acid (50 microg per 30 g body weight). These data suggest that both 5-caffeoylquinic acid and caffeic acid orally administered can be absorbed and suppress P-selectin expression on mouse platelets.     

Selective inhibition of tRNATyr transcription by guanosine 3'-diphosphate 5'-diphosphate.

Guanosine 3'-diphosphate 5'-diphosphate (ppGpp) selectively reduces the synthesis of su+III tRNA from omega 80 psu+III DNA relative to the synthesis of omega 80 RNA in a system in vitro containing DNA and Escherichia coli RNA polymerase holoenzyme as the sole macromolecular components. The response of su+III tRNA synthesis to increasing salt and to temperature in the presence of ppGpp suggests that the nucleotide may reduce the affinity of the enzyme for su+III promoters. The Ki for the selective inhibition of tRNA synthesis by ppGpp is 4 muM in contrast to the value of 150 muM for the inhibition of rRNA synthesis.     

Effects of chronic amiodarone treatment on cat myocardial phospholipid content and on in vitro phospholipid catabolism

Amiodarone is used extensively for the chronic treatment of life-threatening arrhythmias caused by ischemic heart disease. However, chronic therapy with this agent results in phospholipidosis in various tissues and it has been suggested that the inhibition of lysosomal phospholipase A by this drug contributes to this abnormality. Exogenous amiodarone has been shown to inhibit purified rat liver lysosomal phospholipase A₁, as well as acid phospholipase activities of alveolar macrophage homogenates and those of snake venom phospholipase A₂ and bacterial phospholipase C. The effects of drug treatment on heart have not been explored. The results described here demonstrate that amiodarone also significantly increases (37%, p < 0.001) phospholipid content in cat hearts. This increase is proportionately distributed to all major phospholipid classes, with the exception of sphingomyelin which appears to increase more than the others. In addition, the data also show that following amiodarone treatment, the endogenous drug levels in the heart were sufficient to reduce in vitro losses of membrane phospholipid at 37°C by inhibiting a variety of endogenous phospholipases at physiological (7.4), ischemic (6.2) and acidic (5.0) pH values. This protection is more pronounced at acidic pH values than at physiological pH. Endogenous amiodarone also affects myocardial phospholipase activities towards exogenous phosphatidylcholine and again the extent of inhibition is more at acidic pH. These results suggest that amiodarone induces phospholipidosis in the heart by inhibiting phospholipid catabolism and that its antiarrhythmic properties may reside in its ability to modulate alkaline, neutral and acid phospholipase activities in ischemia. To what extent amiodarone metabolites (desethylamiodarone and bis-desethylamiodarone) are involved in these actions remains to be determined.