Simultaneous determination of doxifluridine and 5-fluorouracil in monkey serum by high performance liquid chromatography with tandem mass spectrometry

A reverse-phase high performance liquid chromatography method with electrospray ionization and detection by mass spectrometry is described for the simultaneous determination of doxifluridine and its active metabolite 5-fluorouracil in monkey serum. A liquid/liquid extraction with ethyl acetate (90%) and isopropyl alcohol (10%) was used to extract simultaneously doxifluridine and 5-FU which have considerable difference in the polarity. Optimum chromatographic separation was achieved on a Agilent Zorbax C(18) (100 mm x 2.1mm, 3.5 microm) column with a mobile phase of methanol-water (20:80, v/v). The flow rate was 0.2 mL/min with total cycle time of 5 min. The lower limit of quantification (LLOQ) was validated at 10.0 ng/mL of serum for both doxifluridine and 5-FU. Accuracy and precision of quality control (QC) samples for both compounds met FDA Guidance criteria of +/-15% with average QC accuracy of 95.5-105.0% and coefficients of variation of 1.1-9.5% in the 10-2000 ng/mL concentration range. This method demonstrated adequate sensitivity, specificity, accuracy, precision, stability to support the analysis of monkey serum samples.     

Gain in 1q is a common abnormality in phyllodes tumours of the breast.

We studied DNA copy number changes by CGH and allelic imbalance (AI) on 3p by LOH analysis on 22 phyllodes tumours (PT) of the breast in order to gain insight into the genetic basis of tumour progression in PT. Copy number changes were observed in 14 cases (63%). Gain in 1q with 1q21-23 as the minimal overlapping area was seen in 12 cases (55%). The gain was observed both in benign and malignant tumours. Our study did not reveal any DNA copy number changes or allelic loss on 3p. The results suggest that DNA copy number changes are not associated with the histological grade or clinical behaviour of PT and the chromosomal changes on 3p appear to be rare. Colour figure can be viewed on http://www.esacp.org/acp/2003/25-2/jee.htm     

Rapid increase in endothelial nitric oxide production by bradykinin is mediated by protein kinase A signaling pathway

Bradykinin (BK) acutely increases endothelial nitric oxide (NO) production by activating endothelial NO synthase (eNOS), and this increase is in part correlated with enhanced phosphorylation/dephosphorylation of eNOS by several protein kinases and phosphatases. However, the signaling mechanisms producing this increase are still controversial. In an attempt to delineate the acute effect of BK on endothelial NO production, confluent bovine aortic endothelial cells were incubated with BK, and NO production was measured by NO-specific chemiluminescence. Significant increase in NO levels was detected as early as 1 min after BK treatment, with concomitant increase in the phosphorylation of Ser(1179) (bovine sequence) site of eNOS (eNOS-Ser(1179)). This acute effect of BK on both increases was blocked only by treatment of protein kinase A inhibitor H-89, but not by the inhibitors of calmodulin-dependent kinase II and protein kinase B, suggesting that the rapid increase in NO production by BK is mediated by the PKA-dependent phosphorylation of eNOS-Ser(1179).     

Effect of dietary pectin on the production of immunoglobulins and cytokines by mesenteric lymph node lymphocytes in mouse colitis induced with dextran sulfate sodium

The present study explores the dietary effect of pectin on the MLN lymphocyte functions of mice with dextran sulfate sodium (DS)-induced colitis. We found that the immunoglobulin (Ig)A level in mesenteric lymph node (MLN) lymphocytes was high, while the IgE level was lower, in mice fed with pectin than in those fed with cellulose. Interestingly, the fecal IgA concentration of the pectin-fed mice was significantly higher than that of the cellulose-fed mice. The concentrations of interferon-gamma and interleukin (IL)-2 treated with concanavalin A (ConA) were significantly higher in the pectin-fed group than in the cellulose-fed group. Although dietary pectin did not affect the IL-4 and IL-10 levels, the activation-induced IL-4 and IL-10 secretion was lower in MLN cells of the pectin-fed mice than of the cellulose-fed mice following DS-induced colitis. Based on these findings, we propose that the effect of dietary pectin on mice with DS-induced colitis is mediated by the manipulation of Th1 cells. Furthermore, the inhibitory effect of IL-4 and IL-10 by dietary pectin may play an important role in promoting a change in Th1/Th2 balance toward Th1-dominant immunity.     

Multiple Forms of Phospholipase D following Germination and during Leaf Development of Castor Bean

Multiple molecular forms of phospholipase D (PLD; EC 3.1.4.4) were identified and partially characterized in endosperm of germinated seeds and leaves of castor bean (Ricinus communis L. var Hale). The different PLD forms were resolved by nondenaturing polyacrylamide gel electrophoresis, isoelectric focusing, and size-exclusion chromatography. PLD was detected with both a PLD activity assay and immunoblots with PLD-specific antibodies. There were three major forms of PLD, designated types 1, 2, and 3, based on their mobility during nondenaturing polyacrylamide gel electrophoresis. Molecular masses of the PLD variants were estimated at 330, 230, and 270 kD for the types 1, 2, and 3, respectively. Isoelectric points of the native type 1, 2, and 3 PLDs were approximately 6.2, 4.9, and 4.8. Under the in vitro assay conditions used, the three forms of PLD exhibited the same substrate specificity, hydrolyzing phosphatidylcholine (PC), phosphatidylethanolamine (PE), and phosphatidylglycerol (PG) but not phosphatidylserine (PS) and phosphatidylinositol (PI). The three forms of PLD differed in their substrate preferences, and the order of activities was: PLD 1, PE > PG = PC; PLD 2, PE > PG > PC; PLD 3, PE = PG = PC. The Km values of PLDs 1, 2, and 3 for PC were 1.92, 2.62, and 5.18 mM, respectively. These PLDs were expressed differentially following seed germination and during leaf development. Type 1 was found in the early stages of seedling growth and in young leaves, type 2 was present in all the tissues and growth stages examined, and type 3 was expressed in senescent tissues. The PLDs shifted from largely cytosolic to predominantly membrane-associated forms during leaf development. The present studies demonstrate the structural heterogeneity of plant PLD and growth stage-specific expression of different molecular forms. The possible role for the occurrence of multiple molecular forms of PLD in cellular metabolism is discussed.     

Dysfunction of rat liver mitochondria by selenite: induction of mitochondrial permeability transition through thiol-oxidation

Selenium is an essential trace element in mammals and is thought to play a chemopreventive role in human cancer, possibly by inducing tumor cell apoptosis. Mitochondria play a pivotal role in the induction of apoptosis in many cell types. The effects of selenite on mitochondrial function were therefore investigated. Selenite induced the oxidation and cross-linking of protein thiol groups, mitochondrial permeability transition (MPT), a decrease in the mitochondrial membrane potential, and the release of cytochrome c in mitochondria isolated from rat liver. Induction of the MPT by selenite was prevented by cyclosporin A, EGTA, or N-ethylmaleimide. These results thus indicate that selenite induces the MPT as a result of direct modification of protein thiol groups, resulting in the release of cytochrome c and a loss of mitochondrial membrane potential.