Des aptamères pour améliorer l’encapsulation et la libération contrôlée des liposomes

Mémoire par articleHypothèse : L’incorporation dans des liposomes d’aptamères spécifiques à un principe actif permet d’obtenir une encapsulation active du principe actif et de modifier les profils de libération sans diminuer l’efficacité thérapeutique. Méthode : Une série d’aptamères d’affinité variable a été incorporée dans la préparation de liposomes cationiques. Ces lipoplexes ainsi formés ont été caractérisés en taille par diffusion dynamique de la lumière et par la mesure du potentiel de surface zêta. Ils ont été optimisés en matière de complexation maximale des aptamères, puis incubés avec la doxorubicine, choisie comme principe actif modèle. L’efficacité d’encapsulation de la doxorubicine a été comparée avec et sans aptamères, et contre la méthode d’encapsulation active offerte commercialement. Les meilleures formulations ont été étudiées sur le plan de la cinétique de libération et l’efficacité de celles-ci a été évaluée pour leur cytotoxicité sur des cellules cancéreuses de type HeLa. Résultats : Les vecteurs cationiques optimisés permettent la complexation d’au moins 94% des aptamères. Trois des quatre aptamères ont démontré de l’encapsulation active de la doxorubicine, avec des efficacités d’encapsulation allant jusqu’à 85%. De ces trois formulations, différents profils de libération ont été obtenus, permettant tous une libération plus importante qu’une formulation ressemblant aux liposomes commerciaux de doxorubicine (Doxil®). L’efficacité des trois formulations testées sur les cellules HeLa s'est avérée équivalente ou supérieure au standard similaire du Doxil®.Hypothesis : Incorporation in some liposomes of specific aptamers for a drug allowed the obtaining of active encapsulation of that drug and allowed the modification of their drug release profiles, without negatively impacting its therapeutic efficacy. Methods : A series of aptamers of various affinity were incorporated in the preparation of cationic liposomes. The resulting lipoplexes were characterized for their size by dynamic light scattering method and their surface potential were analysed by zeta potential measurement. Lipoplexes were optimized in terms of highest aptamer complexation and they were incubated with doxorubicin, a model drug that was chosen. The encapsulation efficiency of doxorubicin was compared with and without the presence of aptamers, and with the commercially available active loading method. The best formulations were studied for their doxorubicin’s release kinetic, with the different aptamers, and they were tested for their cytotoxicity on HeLa cancer cells. Results : Cationic liposomes were optimized to allow a minimum aptamer complexation of 94%. Three out of the four tested aptamers were able to demonstrate active loading capabilities, with up to 85% encapsulation efficiencies. Out of these three formulations, very different release profiles were found, all allowing more initial content release of the commercially-like available doxorubicin’s liposomes (Doxil®). The efficacy of those three formulations on HeLa cancer cells demonstrated equivalent or higher cytotoxicity than the similar standard of Doxil®

Fatty acid profile in cord blood of neonates born to optimally controlled gestational diabetes mellitus

OBJECTIVE: To evaluate the fatty acid profile of cord blood phospholipids (PL), cholesteryl esters (CE), triglycerides (TG) and non-esterified fatty acids (NEFA) in neonates born to mothers with gestational diabetes mellitus (GDM) compared to non-diabetic mothers. METHODS: The offspring of 30 pregnant women (15 non-diabetic controls, 15 with diet- or insulin-controlled GDM) were recruited before delivery. Cord blood was collected. After lipid extraction, PL, CE, TG and NEFA were separated by thin layer chromatography and analysed by gas chromatography. RESULTS: In GDM vs. control mothers, maternal glycated haemoglobin (A1C, mean±SD) was not different between groups: 5.3±0.5% vs. 5.3±0.3% (p=0.757), respectively. Cord plasma fatty acids were not different in TG, CE and NEFA between GDM and non-diabetic mothers. However, in PL, levels of palmitate, palmitoleate, oleate, vaccinate and di-homo-gamma-linolenate were significantly lower, with a trend for lower arachidonate (p=0.078), in neonates born to GDM mothers compared to controls. CONCLUSION: In contrast to other studies on cord blood docosahexaenoic acid (DHA) levels in GDM mothers, we did not found lower levels of DHA in cord PL, CE, TG or NEFA in neonates born to GDM compared to non-diabetic mothers

Enhanced Immunogenicity, Mortality Protection, and Reduced Viral Brain Invasion by Alum Adjuvant with an H5N1 Split-Virion Vaccine in the Ferret

Pre-pandemic development of an inactivated, split-virion avian influenza vaccine is challenged by the lack of pre-existing immunity and the reduced immunogenicity of some H5 hemagglutinins compared to that of seasonal influenza vaccines. Identification of an acceptable effective adjuvant is needed to improve immunogenicity of a split-virion avian influenza vaccine.No serum antibodies were detected after vaccination with unadjuvanted vaccine, whereas alum-adjuvanted vaccination induced a robust antibody response. Survival after unadjuvanted dose regimens of 30 µg, 7.5 µg and 1.9 µg (21-day intervals) was 64%, 43%, and 43%, respectively, yet survivors experienced weight loss, fever and thrombocytopenia. Survival after unadjuvanted dose regimen of 22.5 µg (28-day intervals) was 0%, suggesting important differences in intervals in this model. In contrast to unadjuvanted survivors, either dose of alum-adjuvanted vaccine resulted in 93% survival with minimal morbidity and without fever or weight loss. The rarity of brain inflammation in alum-adjuvanted survivors, compared to high levels in unadjuvanted vaccine survivors, suggested that improved protection associated with the alum adjuvant was due to markedly reduced early viral invasion of the ferret brain.Alum adjuvant significantly improves efficacy of an H5N1 split-virion vaccine in the ferret model as measured by immunogenicity, mortality, morbidity, and brain invasion

Twenty-seven-year time trends in dementia incidence in Europe and the United States: The Alzheimer Cohorts Consortium

OBJECTIVE: To determine changes in the incidence of dementia between 1988 and 2015. METHODS: This analysis was performed in aggregated data from individuals >65 years of age in 7 population-based cohort studies in the United States and Europe from the Alzheimer Cohort Consortium. First, we calculated age- and sex-specific incidence rates for all-cause dementia, and then defined nonoverlapping 5-year epochs within each study to determine trends in incidence. Estimates of change per 10-year interval were pooled and results are presented combined and stratified by sex. RESULTS: Of 49,202 individuals, 4,253 (8.6%) developed dementia. The incidence rate of dementia increased with age, similarly for women and men, ranging from about 4 per 1,000 person-years in individuals aged 65-69 years to 65 per 1,000 person-years for those aged 85-89 years. The incidence rate of dementia declined by 13% per calendar decade (95% confidence interval [CI], 7%-19%), consistently across studies, and somewhat more pronouncedly in men than in women (24% [95% CI 14%-32%] vs 8% [0%-15%]). CONCLUSION: The incidence rate of dementia in Europe and North America has declined by 13% per decade over the past 25 years, consistently across studies. Incidence is similar for men and women, although declines were somewhat more profound in men. These observations call for sustained efforts to finding the causes for this decline, as well as determining their validity in geographically and ethnically diverse populations

Neurite Growth and Electrical Activity in PC-12 Cells: Effects of H3 Receptor-Inspired Electromagnetic Fields and Inherent Schumann Frequencies

Cells are continually exposed to a range of electromagnetic fields (EMFs), including those from the Schumann resonance to radio waves. The effects of EMFs on cells are diverse and vary based on the specific EMF type. Recent research suggests potential therapeutic applications of EMFs for various diseases. In this study, we explored the impact of a physiologically patterned EMF, inspired by the H3 receptor associated with wakefulness, on PC-12 cells in vitro. Our hypothesis posited that the application of this EMF to differentiated PC-12 cells could enhance firing patterns at specific frequencies. Cell electrophysiology was assessed using a novel device, allowing the computation of spectral power density (SPD) scores for frequencies between 1 Hz and 128 Hz. T-tests comparing SPD at certain frequencies (e.g., 29 Hz, 30 Hz, and 79 Hz) between the H3-EMF and control groups showed a significantly higher SPD in the H3 group (p < 0.050). Moreover, at 7.8 Hz and 71 Hz, a significant correlation was observed between predicted and percentages of cells with neurites (R = 0.542). Key findings indicate the efficacy of the new electrophysiology measure for assessing PC-12 cell activity, a significant increase in cellular activity with the H3-receptor-inspired EMF at specific frequencies, and the influence of 7.8 Hz and 71 Hz frequencies on neurite growth. The overall findings support the idea that the electrical frequency profiles of developing cell systems can serve as an indicator of their progression and eventual cellular outcomes

Neurovirulence of H5N1 infection in ferrets is mediated by multifocal replication in distinct permissive neuronal cell regions.

Highly pathogenic avian influenza A (HPAI), subtype H5N1, remains an emergent threat to the human population. While respiratory disease is a hallmark of influenza infection, H5N1 has a high incidence of neurological sequelae in many animal species and sporadically in humans. We elucidate the temporal/spatial infection of H5N1 in the brain of ferrets following a low dose, intranasal infection of two HPAI strains of varying neurovirulence and lethality. A/Vietnam/1203/2004 (VN1203) induced mortality in 100% of infected ferrets while A/Hong Kong/483/1997 (HK483) induced lethality in only 20% of ferrets, with death occurring significantly later following infection. Neurological signs were prominent in VN1203 infection, but not HK483, with seizures observed three days post challenge and torticollis or paresis at later time points. VN1203 and HK483 replication kinetics were similar in primary differentiated ferret nasal turbinate cells, and similar viral titers were measured in the nasal turbinates of infected ferrets. Pulmonary viral titers were not different between strains and pathological findings in the lungs were similar in severity. VN1203 replicated to high titers in the olfactory bulb, cerebral cortex, and brain stem; whereas HK483 was not recovered in these tissues. VN1203 was identified adjacent to and within the olfactory nerve tract, and multifocal infection was observed throughout the frontal cortex and cerebrum. VN1203 was also detected throughout the cerebellum, specifically in Purkinje cells and regions that coordinate voluntary movements. These findings suggest the increased lethality of VN1203 in ferrets is due to increased replication in brain regions important in higher order function and explains the neurological signs observed during H5N1 neurovirulence