Vitamin D3 derivatives inhibit the differentiation of Friend erythroleukemia cells

A number of vitamin D3 metabolites inhibit benzodiazepine- and dimethyl sulfoxide-induced differentiation of Friend erythroleukemia cells. The inhibition is dose dependent and occurs at nM concentrations. The order of potency of these compounds is 1,25-dihydroxycholecalciferol greater than 1,25,26-trihydroxycholecalciferol greater than 1,24R,25-trihydroxycholecalciferol greater than 1 alpha-hydroxycholecalciferol greater than 24R,25-dihydroxycholecalciferol greater than 25S,26-dihydroxycholecalciferol. The inhibition is maximal when the vitamin D3 analogs are added together with the inducer, and becomes progressively decreased with delayed addition. These results suggest that the vitamin D3 metabolites may play a regulatory role in erythropoiesis.     

Pharmacokinetics of intravenous bepridil in patients with coronary disease

The pharmacokinetics of intravenous bepridil (1-[2-(N-benzylanilino)-1-(isobutoxymethyl)ethyl]pyrrolidine ) were studied in 16 patients undergoing cardiac catheterization for evaluation of coronary disease, all with normal base-line hemodynamic and renal functions. Ten patients received 3 mg/kg and six patients received 4 mg/kg of bepridil infused over a period of 30 min. Plasma bepridil concentrations were measured by HPLC and analyzed by model-dependent and model-independent methods. The mean (+/- SD) maximum plasma bepridil concentrations at the end of the infusion were 2047 +/- 820 ng/mL (3 mg/kg) and 2478 +/- 1426 ng/mL (4 mg/kg). Postinfusion bepridil concentrations were best described by a two-compartment open model. The model-dependent harmonic mean distribution and elimination half-lives were 1.7 h (range: 1.1-2.2 h) and 19.7 h (range: 8.0-61.9 h), respectively. The harmonic mean elimination half-life from model-independent analysis was 14.9 h (range: 7.4-64.0 h). The arithmetic means of other model-independent kinetic parameters were systemic clearance, 0.524 +/- 0.215 L X kg-1 X h-1; Vd, 15.3 +/- 10.9 L/kg; and Vdss, 10.1 +/- 6.0 L/kg. Model-dependent and model-independent estimates of half-life and clearance agreed reasonably well. Bepridil was well tolerated, effecting little or no change in central hemodynamics or EKG intervals. The extensive distribution and relatively slow clearance of bepridil account for its long elimination half-life. Intravenous bepridil appears to be a safe calcium (II) antagonist that is suitable for once-a-day dosing.     

Anthracycline-based combined chemotherapy in the mouse model.

Our research was aimed at establishing if and how selenium (Se) ion, N-acetylcysteine (NAC), sodium salt of monoketocholic acid (MKH) and superoxide-dismutase (SOD), administered in the experimental animal model, could affect the possible cytotoxicity associated with anthracycline-based combined chemotherapy with doxorubicin, vincristine and prednisolone (DVP). The following biochemical parameters were investigated: the extent of lipid peroxidation (LPx), and the activity of peroxidase (Px), catalase (CAT), glutathione-peroxidase (GSHPx), and xanthine-oxidase (XOD). A statistical increase in LPx activity was obtained by SOD, MKH, DVPSe and DVPMKH. All chemotherapeutic agents reduced Px activity in a statistically significant manner. There was no statistical significance for the results regarding the effects of the administered substances on GSHPx activity. The results for DVP, SOD, MKH, DVPSOD, DVPSe and DVPMKH showed reduced XOD activity which was statistically significant, which was lowest in the case of MKH, while NAC and Se reduced the activity of this enzyme but statistically non significant. NAC, Se, DVP, MKH and DVPMKH caused a reduction in CAT activity, while DVPSOD and DVPSe caused an increase of the latter.     

Derivatives of condensed thienopyrimidines: Synthesis and anticonvulsant and tranquilizer activity of hydrochlorides of pyrano[4′,3′:4,5]thieno[3,2-e]imidazo[1,2-a]pyrimidines

New methods for the synthesis of 4-substituted 6,7-dihydro-7,7-dimethyl-5-oxo-9H-pyrano-[4′,3′: 4,5]-thieno[3,2-e]imidazo[1,2-a]pyrimidines and their hydrochlorides are developed. The anticonvulsant and tranquilizer properties of newly synthesized compounds have been studied. __________ Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 41, No. 11, pp. 22–24, November, 2007.     

Autophagy-mediated chemosensitizing effect of the plant alkaloid voacamine on multidrug resistant cells.

In our previous studies, voacamine, a bisindolic alkaloid extracted from Peschiera fuchsiaefolia, was examined for its possible capability of enhancing the cytotoxic effect of doxorubicin (DOX) on multidrug resistant (MDR) human osteosarcoma cells (U-2 OS-R). Voacamine induced in resistant cells a significant increase of drug retention and intranuclear location which became comparable to those observed in the parental sensitive counterparts (U-2 OS-WT). In the present study, the cell survival analysis and the electron microscopic observations confirmed the evident cytotoxicity of DOX on MDR cells after pre-treatment with the plant extract. Moreover, an increase of the reactivity of P-glycoprotein (P-gp) with the monoclonal antibody UIC2, which recognizes an epitope of the drug transporter in its functional conformation, was revealed, demonstrating that voacamine is a substrate of P-gp, thus acting as a competitive antagonist of the cytotoxic agent. Moreover, to investigate if the enhancement of the cytotoxic effect induced by voacamine could be due to an apoptotic process, we carried out the analysis of cell morphology after Hoechst staining and the quantification of apoptosis by Annexin V-FITC assay. These evaluations showed a very low rate of apoptosis in U-2 OS-R cells treated with voacamine and DOX given in association. In addition, the combined treatment induced ultrastructural modifications suggestive of autophagic cell death. In particular, transmission electron microscopy observations revealed the presence of numerous lysosomes and the formation of a large number of autophagosomes containing residual digested material. In conclusion, these findings seem to indicate that voacamine is capable of enhancing the cytotoxic effect of DOX on MDR cells by favouring a lethal autophagic process.     

The effects of severe visual challenges on steering performance in visually healthy young drivers.

PURPOSE: Two experiments explored the extent to which induced blur, reduced luminance, and reduced visual fields affect drivers' steering performance in a driving simulator. METHODS: In experiment 1, ten young participants (M = 21.2 years) drove at approximately 89 km/h (55 mph) along a curvy roadway while being exposed to blur (0 to + 10 D), luminance (0.003 to 16.7 cd/m), and visual field (1.7 and 150 degrees) manipulations. In experiment 2, a new group of ten young participants (M = 18.5 years) drove while exposed to seven visual field sizes (1.7 to 150 degrees). RESULTS: Steering was sensitive to a reduced field size but not to the blur and luminance challenges. Acuity, on the other hand, was sensitive to the blur and luminance challenges but not to reduced field size. DISCUSSION: In healthy young drivers, steering performance is remarkably robust to severe blur and to extremely low luminances. These results support a key element of the selective degradation hypothesis advanced by Leibowitz and colleagues--that steering abilities are preserved at night even when the ability to recognize objects and hazards is not. Additional research should address the other element of this hypothesis--that drivers fail to appreciate the extent to which their visual abilities are degraded at night.