Arachidonic acid modulates [14C]stearic acid incorporation into phosphatidylinositol,in human neuroblastoma cells

In the human neuroblastoma cell line SK-N-BE(2), arachidonic acid (AA), supplied in the medium at micromolar concentrations, markedly ehnanced [¹⁴C]stearic acid (SA) (but not [¹⁴C]palmitic acid or [¹⁴C]oleic acid) incorporation into phosphatidylinositol (PtdIns). AA failed to stimulate [¹⁴C]SA incorporation into PtdIns precursors, namely phosphatidic acid and cytidinediphosphodiacylglycerol; furthermore, enhanced [¹⁴C]SA incorporation, brought about by exogenously administered AA, was not restricted to PtdIns tetraenoic species. When cells were pulsed for 1 h with [¹⁴C]SA (either in the presence or absence of AA) and then reincubated in AA- and [¹⁴C]SA-free medium, a marked loss of radioactivity from PtdIns was observed, that however was restricted to molecular species other than tetraenoic. These results are discussed in the light of possible mechanisms through which PtdIns achieves the 1-stearoyl-2-arachidonoyl configuration.     

Effects of the Calcium Antagonist Felodipine on Resting and Stress Testing Blood Pressure in Essential Hypertension

The current study analyzed the effects of different doses of the calcium channel blocker felodipine on cardiovascular response to a set of standardized laboratory tasks. We randomly allocated 21 essential hypertensive patients to receive extended release felodipine 5 mg, felodipine 10 mg and placebo, each given once daily for 2 weeks, according to a double-blind 3-period design. At the end of each treatment period, patients were examined at resting baseline and while performing a mental arithmetic test, a handgrip test and a cycle ergometry test. Compared to placebo, the average fall in resting blood pressure (BP) was of 7.9 ± 5.6/6.1 ± 4.5 mm Hg with felodipine 5 mg (p < 0.01) and of 15.1 ± 5.8/13.9 ± 4.5 mm Hg with felodipine 10 mg (p < 0.001). During mental arithmetic, BP decrease was 11.6 ± 8.1/9 ± 5 mm Hg with felodipine 5 mg (p < 0.01) and 20.4 ± 8.1/15.3 ± 5 mm Hg with felodipine 10 mg (p < 0.001). During handgrip test, BP was significantly reduced after both felodipine doses by 11.7 ± 9.3/9.5 ± 6.5 mm Hg (p < 0.05) and 22.1 ± 9.3/22.4 ± 6.5 mm Hg (p < 0.001), respectively. During cycle ergometry, systolic BP was significantly reduced after felodipine 10 mg by 20.1 ± 9.4 mm Hg (p < 0.001), whereas the fall induced by felodipine 5 mg (7.7 ± 9.4 mm Hg) was not statistically significant (p > 0.05); diastolic BP was significantly reduced by both felodipine doses [average fall of 6.6 ± 5.8 mm Hg (p < 0.05) after felodipine 5 mg and of 12.7 ± 5.8 mm Hg (p < 0.001) after felodipine 10 mg]. There was no treatment effect on the magnitude of systolic BP reactivity from baseline during either mental arithmetic, handgrip test or cycle ergometry (all, p > 0.05). Heart rate values were significantly higher after both felodipine doses than after placebo, either at rest or during stress testing (all, p < 0.05). These data suggest that felodipine, especially at higher doses, may be effective in lowering BP not only at rest but also during exposure to commonly recurring stressful situations.     

Quercetin potentiates the effect of adriamycin in a multidrug-resistant MCF-7 human breast-cancer cell line: P-glycoprotein as a possible target

This study demonstrates that the flavonoid quercetin (Q), a plant-derived compound with low toxicity in vivo, greatly potentiates the growth-inhibitory activity of Adriamycin (ADR) on MCF-7 ADR-resistant human breast cancer cells. The effect of Q was dose-dependent at concentrations ranging between 1 and 10 M. Since ADR resistance in these cells is associated with the expression of high levels of P-glycoprotein (Pgp), we evaluated the effect of Q and related flavonoids of Pgp activity in cytofluorographic efflux experiments with the fluorescent dye rhodamine 123 (Rh 123). Our results indicate that Q and 3-OMe Q (3,4,7-trimethoxyquercetin) but not the 3-rhamnosylglucoside of Q (rutin) inhibit the Pgp pump-efflux activity in a dose-related manner. Moreover, 10 M Q reduces the expression of the immunoreactive Pgp in MCF-7 ADR-resistant cells as evaluated by cytofluorimetric assay. In conclusion, these findings provide a further biological basis for the potential therapeutic application of Q as an anticancer drug either alone or in combination with ADR in multidrug-resistant breast tumor cells.This work was partially supported by grants from MURST (60% and 40%) and CNR (Special Projects: A.C.R.O. 94.01098.PF 39); R. DeVincenzo and G. Ferrandina are recipients of fellowships from the Italian Association for Cancer Research (AIRC); M. Cianfriglia was partly supported by the AIDS research project (contract 720/P)     

Postzygotic instability of the myotonic dystrophy p[AGC]n repeat supported by larger expansions in muscle and reduced amplifications in sperm

We have analysed the [AGC] expansion in leucocytes, muscle and sperm from 17 individuals affected by myotonic dystrophy (DM). Skeletal muscle showed a larger repeat number than leucocytes in the same patient. A similar degree of expansion was detected in differently affected muscles of a single patient. The germline mutation ( 350 repeats) was expanded in somatic cells of the progeny in all patients examined. Our results provide evidence of an early postzygotic instability of the [AGC] repeat in DM.     

Preparation and local anaesthetic activity of benzotriazinone and benzoyltriazole derivatives

Two sets of benzotriazinone and benzoyltriazole derivatives were prepared and tested for local anaesthetic activity in comparison with lidocaine. Several of the prepared compounds exhibited a fairly good activity comparable or superior to that of lidocaine. The presence of a benzotriazinone or a benzoyltriazole moiety as an aromatic system was quite profitable for both the intensity and duration of activity. The acute toxicity in mice of the four most potent compounds of the series was also assessed. Compound 1b, which has an anaesthetic activity comparable to that of lidocaine, was also characterized by a more favourable therapeutic index. All compounds were tested in vitro to evaluate their negative chronotropic action in isolated rat right atria.     

Quercetin inhibits the growth of a multidrug-resistant estrogen-receptor-negative MCF-7 human breast-cancer cell line expressing type II estrogen-binding sites

Summary It has been demonstrated that the flavonoid quercetin (3,3,4,5,7-pentahydroxyflavone; Q) inhibits the growth of several cancer cell lines. There is evidence suggesting that the antiproliferative activity of this substance is mediated by the so-called type II estrogen-binding, site (type II EBS). We looked for the presence of type II EBS and the effect of Q on the proliferation of an Adriamycinresistant estrogen-receptor-negative human breast-cancer cell line (MCF-7 ADRr). By whole-cell assay using estradiol labelled with 6,7-tritium ([³H]-E2) as a tracer, we demonstrated that MCF-7 ADRr cells contain type II EBSs. Competition analysis revealed that diethylstilbestrol (DES) and Q competed with similar potency for [³H]-Es binding to type II EBSs. The antiestrogen tamoxifen (TAM) competed for type II EBSs, albeit to a lesser extent than either DES or Q. Growth experiments demonstrated that Q and DES exerted a dose-dependent inhibition of cell proliferation in the range of concentrations between 10 nM and 10 m, whereas TAM was less effective. Q could also inhibit colony formation in a clonogenic assay. Our results indicate that multidrug-resistant estrogen-receptor-negative MCF-7 cells express, type II EBSs and are sensitive to the inhibitory effect of Q. This substance could be the parent compound of a novel class of anticancer agents.