Aims: Radiolabeled antisense oligonucleotide to target the mRNA of the hmdr1 gene for diagnostic purposes is a new concept for evaluating the chemoresistance of tumors in vivo. Methods and Results: An 18 mer complementary to the zone which contains the translation initiation codon of the hmdr1 gene was modified using one phosphoramidate group and one. dimethoxytrityle group at the 5' and 3'ends. It permitted probe radiolabeling by I-125 Chemical modifications made to the antisense probe ensured the stability in biological media tested by incubation with human serum at 37degreesC from 5 minutes to 24 hours. These modifications did not interfere with recognition of the target. Retention of the antisense probe followed the expression level of the target transcript in in vitro and in vivo studies. In vitro, after a 2-hour incubation in the presence of K562 - sensitive (S) and- resistant (R) cell lines, uptake was respectively 4.27 +/- 0.96% ID/mg protein and 7.78 +/- 0.46% ID/mg protein (p<0.001). In vivo, the ratios between radioactivity found in the tumor and that found in the striated muscle and in the blood were, respectively, 20 and 3 for IGR OV1 resistant tumor and 1 and 0.3 for the sensitive one. Conclusion: In our study, resistant cell lines and tumor showed greater retention of the specific probe than the sensistive ones. This constitutes a further advance towards non invasive imaging of resistant genes involved in chemoresistance. These results are encouraging: the current trend in innovative cancer therapy is moving towards targeting the genes of interest.

The current trend in innovative cancer therapy is moving towards targeting the genes of interest by means of oligonucleotides developed for therapeutic or diagnostic use. These new approaches are of particular interest in oncology, and it would therefore be extremely useful to characterise all the biological tools currently available in this field. The chemoresistance profiles of four human cancer cell lines were determined by identifying of the operating conditions needed to characterise the presence of hmdr1, mrp and lrp mRNA by gene amplification.

In the pathogenesis of acne inflammation, Propionibacterium acnes seems to play an important initiating role by producing low-molecular-weight chemotactic factors , resulting in the accumulation of neutrophils at the site of acne comedones. The role of reactive oxygen species (ROS) generated by neutrophils has been shown in mediating tissue damage. The aim of this study was to investigate the possible role of ROS generated by neutrophils in mediating acne inflammation. We attempted to analyze the production of hydrogen peroxide by neutrophils from patients with comedonal type of acne, patients with papulopustular type of acne, and healthy controls , using a two-dimensional flow cytometric assay. Neutrophils from patients with papulopustular type of acne produced a statistically greater amount of hydrogen peroxide than those from patients with comedonal type of acne after stimulation with Staphylococcus aureus (p < 0.01 ). No statistical difference was observed between the comedonal type of acne and healthy controls. In addition, amount of hydrogen peroxide generated by neutrophils from patients with papulopustular type of acne was significantly decreased after the treatment with oral administration of standard doses of minocycline (p < 0.01 ). Our results seem to suggest that ROS generated by neutrophils contribute to the damage of follicular epithlium leading to the extrusion of follicular contents into the dermis, and subsequently resulting in a variety of inflammatory processes.

The association of verapamil with halothane causes ischaemic-like myocardial dysfunction. Using an isolated rat heart model perfused with a radiolabelled fatty acid (123I-labelled iodohexadecenoic acid) as a sensitive marker of ischaemia this study investigated whether or not this dysfunction is of ischaemic origin. Hearts were perfused with a control solution or with solutions containing either 1% of halothane or 150 ng ml-1 of verapamil or the association of 0.75% halothane + 120 ng ml-1 verapamil. The ischaemic group was perfused at a reduced perfusion rate (-50%). Intracellular fate of IHA was assessed, and its esterification ratio computed. Ischaemia and the drugs induced a similar depression of haemodynamics. The esterification ratio in the ischaemic group was significantly higher (0.723 +/- 0.04) than in controls (0.0526 +/- 0.03) and than in the treated groups: halothane (0.533 +/- 0.06), verapamil (0.411 +/- 0.027) or the association halothane+verapamil (0.408 +/- 0.05), suggesting a non-ischaemic origin for the dysfunction caused by halothane-verapamil.

The study of myocardial metabolism by external detection is now achieved with iodinated fatty acids (IFAs). I-123-Iodohexadecenoic acid (IHA) is injected as a bolus into isolated and perfused rat hearts. The myocardial time-activity curve is recorded with a detection system and a mathematical compartmental analysis of the external detection curve provides data on the intracellular fate of the labeled FA (esterification ratio, lipolysis, iodide release). Studies have been performed on rat hearts under various physiological conditions (influence of 36 hour fasting, of the presence of glucose or POCA, an inhibitor of FA oxidation). The time-activity curves are modified under these various conditions and the rate constants obtained from the mathematical analysis demonstrate a decrease of the esterification ratio with 36 hour fasting or without glucose, and an increase of this ratio with POCA. It was also necessary to demonstrate that these data on metabolism were reliable values. The data have been validated by an intracellular analysis of the fate of IHA in the myocardium and confirm the suitability of our mathematical model applied to the external detection curves obtained with IHA for the study of myocardial metabolism.

In order to study myocardial metabolism by external detection, quantitative information on the metabolism of a gamma-emitting iodinated fatty acid (IHA) was obtained from time-activity curves of radioactivity in different compartments. A 4-compartment mathematical model was then developed; compartments 0, 1, 2, and 3 correspond respectively to vascular IHA, intracellular IHA, esterified forms, and iodide resulting from mitochondrial oxidation of IHA. We applied this model to a study of the influence of an inhibitor of fatty acid oxidation, POCA (2-[5(4 chlorophenyl) pentyl]-oxirane-2-carboxylate). Isolated rat hearts were perfused for 20 min with Krebs liquid containing increasing concentrations of POCA. IHA was then injected as a bolus at the entrance of the coronary network. The level of cardiac radioactivity was recorded for 30 min and the division into the 4 compartments was simulated at different concentrations of POCA. The drug appeared to increase the myocardial retention of IHA and slow down the speed of degradation and storage; the variations were dose-dependent. These results correspond to those obtained by intracellular analysis. The proposed method, which is reliable and sensitive, is an interesting experiment for pharmacological studies of cardiac metabolism.