Epidemiology of transient ischemic attack in the normandy stroke population-based study.

INTRODUCTION: Transient ischemic attack (TIA) is a frequent neurological emergency which management and definition have changed radically over the last 15 years. However, recent epidemiological studies of TIA are scarce. We report here on the impact of the shift from a time-based to a tissue-based definition of TIA on its incidence and risk of recurrence in a new population-based cohort with a high rate of patients investigated by MRI. MATERIALS AND METHODS: We prospectively included all TIAs that occurred between May 2017 and May 2021 from the Normandy Stroke Study, a population-based registry using multiple overlapping sources for exhaustive case identification in Caen la Mer area. TIAs were classified as either time-based (symptoms <24 h) or tissue-based (<24 h and no lesion on brain imaging). Attack and incidence rates were calculated, as was the 90-day ischemic stroke rate. RESULTS: Five hundred and sixty-seven TIAs (549 single patients) were included, with 80.6% having a brain MRI. Four hundred and ten (72.3%) met the definition of tissue-based TIA. The age standardized attack (to the 2013 European population) rate was 39.5 (95% CI 35.7-43.5) and the age-standardized incidence rate (first ever cerebrovascular event) was 29.7 (95% CI 27.3-34.2). The overall recurrent stroke rate at 90 days was 2.7%, with no difference between patients with or without ischemic lesions on MRI. CONCLUSION: We found that the use of the tissue-based definition of TIA resulted in a 27.5% reduction in incidence as compared to the time-based definition, but had no impact on the 90-day stroke rate. The burden of TIA remains high, and is likely to increase as the population ages.

Incidence and Outcomes of Acute Cerebrovascular Events: Methodology of the Population-Based Normandy Stroke Study.

BACKGROUND: The number of strokes has been steadily increasing due to the aging of the population, and its management has changed dramatically in recent years. Nevertheless, there are few unbiased epidemiological studies to investigate the incidence of strokes and their long-term prognosis. METHODS: The Normandy Stroke Study (NSS) is a prospective population-based study of all strokes and transient ischemic attacks in a large urban, suburban, and rural area in the Northwest of France. It was designed to meet the current gold standard in stroke epidemiological study by using multiple overlapping sources for case identification. It also aimed to assess the impact of socioeconomic disparities and long-term prognosis of stroke through an additional follow-up up to 3 years after the event to better understand the functional and cognitive prognostic of stroke as well as the quality of life in patients after stroke. CONCLUSION: NSS will provide important data on the epidemiology and long-term consequences of stroke at the population level and will help care providers adapt resource allocation.

In vitro selection of RNA aptamers derived from a genomic human library against the TAR RNA element of HIV-1.

The transactivating responsive (TAR) element is a RNA hairpin located in the 5' untranslated region of HIV-1 mRNA. It is essential for full-length transcription of the retroviral genome and therefore for HIV-1 replication. Hairpin aptamers that generate highly stable and specific complexes with TAR were previously identified, thus decreasing the level of TAR-dependent expression in cultured cells [Kolb, G., et al. (2006) RNA Biol. 3, 150-156]. We performed genomic SELEX against TAR using a human RNA library to identify human transcripts that might interact with the retroviral genome through loop-loop interactions and potentially contribute to the regulation of TAR-mediated processes. We identified a genomic aptamer termed a1 that folds as a hairpin with an apical loop complementary to five nucleotides of the TAR hexanucleotide loop. Surface plasmon resonance experiments performed on a truncated or mutated version of the a1 aptamer, in the presence of the Rop protein of Escherichia coli, indicate the formation of a highly stable a1-TAR kissing complex. The 5' ACCCAG loop of a1 constitutes a new motif of interaction with the TAR loop.

Aptamers targeting RNA molecules.

Oligonucleotides complementary to RNA sequences interact poorly with folded target regions. In vitro selection of oligonucleotides carried out against RNA structures have led to aptamers that frequently differ from antisense sequences, but rather take advantage of non-double-stranded peculiarities of the target. Studies along this line provide information about tertiary RNA architectures as well as their interaction with ligand of interest. We describe here a genomic SELEX approach and its application to the recognition of stem-loop structures prone to the formation of kissing complexes. We also provide technical details for running a procedure termed 2D-SELEX that takes advantage of both in vitro selection and dynamic combinatorial chemistry. This allows selecting aptamer derivatives containing modified nucleotides that cannot be incorporated by polymerases. Last we present in vitro transcription conditions under which large amounts of RNA, suitable for NMR structural studies, can be obtained. These different aspects of the SELEX technology have been applied to the trans-activating responsive element of the human immunodeficiency virus type 1, which is crucial for the transcription of the retroviral genome.