Cell cycle-dependent cytotoxicity and induction of apoptosis by liposomal N4-hexadecyl-1-beta-D-arabinofuranosylcytosine.

The clonogenic growth inhibition, the cell cycle dependence of N4-hexadecyl-1-beta-D-arabinofuranosylcytosine (NHAC) cytotoxicity and the capability to induce apoptosis in ara-C-sensitive and -resistant HL-60 cells were investigated and compared with arabinofuranosylcytosine (ara-C). In the clonogenic assay with sensitive HL-60 cells, ara-C was slightly more effective than a liposomal preparation of NHAC, whereas in the resistant cells, NHAC revealed its potency to overcome ara-C resistance, resulting in a 23-fold lower 50% inhibitory concentration compared with ara-C. Cell cycle dependent cytotoxicity and induction of apoptosis were studied by flow cytometry, using the bromodeoxyuridine-propidium iodide and terminal transferase method respectively. In contrast to ara-C, NHAC exerted no phase-specific toxicity at low concentrations (< 40 microM). At higher concentrations the S-phase-specific toxicity increased, probably resulting from ara-C formed from NHAC. NHAC induced apoptosis at higher drug concentrations than ara-C, however apoptosis appeared not to be limited to the S-phase cells. Apoptosis occurred in both cell lines within 2-4 h after drug exposure. These results give further evidence that NHAC exerts its cytotoxicity by different mechanisms of action than ara-C and might therefore be active in ara-C-resistant tumours

Comparative pharmacokinetic and cytotoxic analysis of three different formulations of mitoxantrone in mice.

Two liposomal formulations of mitoxantrone (MTO) were compared with the aqueous solution (free MTO) in terms of their pharmacokinetic behaviour in ICR mice and cytotoxic activity in a nude mouse xenograft model. The three different formulations of MTO [free MTO, phosphatidic acid (PA)-MTO liposomes, pH-MTO liposomes] were administered intravenously (three mice per formulation and time point) at a dose of 4.7 micromol kg(-1) for free MTO, 6.1 micromol kg(-1) for PA-MTO and 4.5 micromol kg(-1) for pH-MTO. The concentrations of MTO were determined using high-performance liquid chromatography (HPLC) in blood, liver, heart, spleen and kidneys of the mice. Additionally, the toxicity and anti-tumour activity of MTO was evaluated in a xenograft model using a human LXFL 529/6 large-cell lung carcinoma. The dose administered was 90% of the maximum tolerated dose (MTD) of the corresponding formulation (8.1 micromol kg(-1) for free MTO, 12.1 micromol kg(-1) for PA-MTO and pH-MTO). The pharmacokinetic behaviour of PA-MTO in blood was faster than that of free MTO, but the cytotoxic effect was improved. In contrast, pH-MTO showed a tenfold increased area under the curve (AUC) in blood compared with free MTO, without improvement of the cytotoxic effect. This discrepancy between the pharmacokinetic and cytotoxic results could be explained by the fact that MTO in pH-MTO liposomes remains mainly in the vascular space, whereas MTO in PA-MTO liposomes is rapidly distributed into deep compartments, even more so than free MTO

Cytotoxic targeting of F9 teratocarcinoma tumours with anti-ED-B fibronectin scFv antibody modified liposomes

We prepared small unilamellar liposomes derivatised with single chain antibody fragments specific for the ED-B domain of B-fibronectin. This extracellular matrix associated protein is expressed around newly forming blood vessels in the vicinity of many types of tumours. The single chain antibody fragments were functionalised by introduction of C-terminal cysteines and linked to liposomes via maleimide groups located at the terminal ends of poly(ethylene glycol) modified phospholipids. The properties of these anti-ED-B single chain antibody fragments-liposomes were analysed in vitro on ED-B fibronectin expressing Caco-2 cells and in vivo by studying their biodistribution and their therapeutic potential in mice bearing subcutanous F9 teratocarcinoma tumours. Radioactively labelled (114mIndium) single chain antibody fragments-liposomes accumulated in the tumours at 2–3-fold higher concentrations during the first 2 h after i.v. injection compared to unmodified liposomes. After 6–24 h both liposome types were found in similar amounts (8–10% injected dose g−1) in the tumours. Animals treated i.v. with single chain antibody fragments-liposomes containing the new cytotoxic agent 2′-deoxy-5-fluorouridylyl-N4-octadecyl-1-β-D-arabinofuranosylcytosine (30 mg kg-1 per dose, five times every 24 h) showed a reduction of tumour growth by 62–90% determined on days 5 and 8, respectively, compared to animals receiving control liposomes. Histological analysis revealed a marked reduction of F9 tumour cells and excessive deposition of fibronectin in the extracellular matrix after treatment with single chain antibody fragments-2-dioxy-5-fluorouridylyl-N4-octadecyl-1-β-D-arabinofuranosylcytosine-liposomes. Single chain antibody fragments-liposomes targeted to ED-B fibronectin positive tumours therefore represent a promising and versatile novel drug delivery system for the treatment of tumours

The genetic susceptibility to type 2 diabetes may be modulated by obesity status: implications for association studies

<p>Abstract</p> <p>Background</p> <p>Considering that a portion of the heterogeneity amongst previous replication studies may be due to a variable proportion of obese subjects in case-control designs, we assessed the association of genetic variants with type 2 diabetes (T2D) in large groups of obese and non-obese subjects.</p> <p>Methods</p> <p>We genotyped <it>RETN</it>, <it>KCNJ11</it>, <it>HNF4A</it>, <it>HNF1A</it>, <it>GCK</it>, <it>SLC30A8</it>, <it>ENPP1</it>, <it>ADIPOQ</it>, <it>PPARG</it>, and <it>TCF7L2 </it>polymorphisms in 1,283 normoglycemic (NG) and 1,581 T2D obese individuals as well as in 3,189 NG and 1,244 T2D non-obese subjects of European descent, allowing us to examine T2D risk over a wide range of BMI.</p> <p>Results</p> <p>Amongst non-obese individuals, we observed significant T2D associations with <it>HNF1A </it>I27L [odds ratio (OR) = 1.14, <it>P </it>= 0.04], <it>GCK </it>-30G>A (OR = 1.23, <it>P </it>= 0.01), <it>SLC30A8 </it>R325W (OR = 0.87, <it>P </it>= 0.04), and <it>TCF7L2 </it>rs7903146 (OR = 1.89, <it>P </it>= 4.5 × 10^-23), and non-significant associations with <it>PPARG </it>Pro12Ala (OR = 0.85, <it>P </it>= 0.14), <it>ADIPOQ </it>-11,377C>G (OR = 1.00, <it>P </it>= 0.97) and <it>ENPP1 </it>K121Q (OR = 0.99, <it>P </it>= 0.94). In obese subjects, associations with T2D were detected with <it>PPARG </it>Pro12Ala (OR = 0.73, <it>P </it>= 0.004), <it>ADIPOQ </it>-11,377C>G (OR = 1.26, <it>P </it>= 0.02), <it>ENPP1 </it>K121Q (OR = 1.30, <it>P </it>= 0.003) and <it>TCF7L2 </it>rs7903146 (OR = 1.30, <it>P </it>= 1.1 × 10^-4), and non-significant associations with <it>HNF1A </it>I27L (OR = 0.96, <it>P </it>= 0.53), <it>GCK </it>-30G>A (OR = 1.15, <it>P </it>= 0.12) and <it>SLC30A8 </it>R325W (OR = 0.95, <it>P </it>= 0.44). However, a genotypic heterogeneity was only found for <it>TCF7L2 </it>rs7903146 (<it>P </it>= 3.2 × 10^-5) and <it>ENPP1 </it>K121Q (<it>P </it>= 0.02). No association with T2D was found for <it>KCNJ11</it>, <it>RETN</it>, and <it>HNF4A </it>polymorphisms in non-obese or in obese individuals.</p> <p>Conclusion</p> <p>Genetic variants modulating insulin action may have an increased effect on T2D susceptibility in the presence of obesity, whereas genetic variants acting on insulin secretion may have a greater impact on T2D susceptibility in non-obese individuals.</p

Research achievements in plant resistance to insect pests of cool season food legumes

Plant resistance to at least 17 field and storage insect pests of cool season food legumes has been identified. For the most part, this resistance was located in the primary gene pools of grain legumes via conventional laboratory, greenhouse, and field screening methods. The use of analytical techniques (i.e., capillary gas chromatography) to characterize plant chemicals that mediate the host selection behavior of pest insects offers promise as a new, more rapid way to differentiate between insect-resistant and susceptible plant material. Examples of research achievements in mechanisms of resistance and host-plant resistance within the context of integrated control programs are discussed. Accelerating the development and subsequent releases of insect-resistant cultivars to pulse farmers requires more involvement from interdisciplinary teams of plant breeders, entomologists, plant pathologists, plant chemists, molecular biologists, and other scientist

Cellular pharmacology of a liposomal preparation of N4-hexadecyl-1-beta-D-arabinofuranosylcytosine, a lipophilic derivative of 1-beta-D-arabinofuranosylcytosine

The in vitro deamination, cytotoxicity, cellular drug uptake, distribution and cellular pharmacology in HL-60 cells of N4-hexadecyl-1-beta-D-arabinofuranosylcytosine (NHAC), a lipophilic derivative of arabinofuranosylcytosine (ara-C), were studied. Compared with ara-C, NHAC in liposomal formulations was highly resistant to deamination, resulting in levels of formation of arabinofuranosyluracil 42 and ten times lower in plasma and liver microsomes respectively. The cytotoxicity of NHAC was independent of both the nucleoside transporter mechanism and the deoxycytidine (dCyd) kinase activity as demonstrated by co-incubating NHAC with dipyridamole and/or dCyd. In ara C-resistant HL-60 cells NHAC was still cytotoxic, requiring drug concentration only 1.6 times higher than sensitive cells. Uptake of NHAC was six times higher and was not inhibited by dipyridamole. The pharmacokinetics of NHAC revealed that its intracellular half-life is 4.8 times longer than that of ara-C. Ara-CTP formation and incorporation into DNA was up to 25-50 times lower than that of ara-C and contributed only marginally to the cytotoxic effects of NHAC. These results indicate that, because of the significantly increased stability, the transporter-independent uptake and the dCyd-kinase-independent cytotoxicity, NHAC might be active in ara-C-resistant cells