Aptamers: a novel targeted theranostic platform for pancreatic ductal adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is an extremely challenging disease with a high mortality rate and a short overall survival time. The poor prognosis can be explained by aggressive tumor growth, late diagnosis, and therapy resistance. Consistent efforts have been made focusing on early tumor detection and novel drug development. Various strategies aim at increasing target specificity or local enrichment of chemotherapeutics as well as imaging agents in tumor tissue. Aptamers have the potential to provide early detection and permit anti-cancer therapy with significantly reduced side effects. These molecules are in-vitro selected single-stranded oligonucleotides that form stable three-dimensional structures. They are capable of binding to a variety of molecular targets with high affinity and specificity. Several properties such as high binding affinity, the in vitro chemical process of selection, a variety of chemical modifications of molecular platforms for diverse function, non-immunoreactivity, modification of bioavailability, and manipulation of pharmacokinetics make aptamers attractive targets compared to conventional cell-specific ligands. To explore the potential of aptamers for early diagnosis and targeted therapy of PDAC - as single agents and in combination with radiotherapy - we summarize the generation process of aptamers and their application as biosensors, biomarker detection tools, targeted imaging tracers, and drug-delivery carriers. We are furthermore discussing the current implementation aptamers in clinical trials, their limitations and possible future utilization.

[Are there any advantages in immediate assisted fertilization compared with differed fertilization?]. / La fécondation assistée immédiate (FAI) présente-t-elle des avantages par rapport à la fécondation différée (FAD)?

OBJECTIVES: To demonstrate a difference between the two assisted fertilization procedures. Can either of these procedures be preferred on the basis of preoperative parameters or criteria? A protocol was created to facilitate the patient's decision, as the results of IAF are better that those of DAF. METHODS: We have performed 39 in vitro fertilizations after testicular or epididymal sperm extraction since December 1995. We performed deferred assisted fertilization (DAF) in 19 patients with normal hormone assessment and normal testicular volume or after vasectomy and immediate assisted fertilization (IAF) for 20 patients with an abnormal assessment. RESULTS: The two groups, IAF and DAF, were homogeneous and did not present any differences in terms of age, aetiology of sterility, risk factors or preoperative hormonal parameters. Direct examination of sperm samples, the site of sampling and histological examination did not demonstrate any significant difference between the two groups. ICSI (IntraCytoplasmic Sperm Injection) was performed for 16 couples by IAF and for 14 couples by DAF. We obtained 6 pregnancies (37.5%) in the IAF group and 2 pregnancies (14.3%) in the DAF group. The two groups were identical in terms of the number of oocytes taken and embryos transferred. CONCLUSION: No significant difference was observed between the immediate and deferred fertilization techniques in terms of predictive factors, histology and quality of the direct examination, but the pregnancy rate was higher for IAF. We therefore think that this method should be preferred as the first-line procedure.