Effects of the variation of fundamental constants on Pop III stellar evolution

A variation of the fundamental constants is expected to affect the thermonuclear rates important for stellar nucleosynthesis. In particular, because of the very small resonant energies of Be8 and C12, the triple $\alpha$ process is extremely sensitive to any such variations. Using a microscopic model for these nuclei, we derive the sensitivity of the Hoyle state to the nucleon-nucleon potential allowing for a change in the magnitude of the nuclear interaction. We follow the evolution of 15 and 60 solar mass, zero metallicity stellar models, up to the end of core helium burning. These stars are assumed to be representative of the first, Population III stars. We derive limits on the variation of the magnitude of the nuclear interaction and model dependent limits on the variation of the fine structure constant based on the calculated oxygen and carbon abundances resulting from helium burning. The requirement that some C12 and O16 be present are the end of the helium burning phase allows for permille limits on the change of the nuclear interaction and limits of order 10^{-5} on the fine structure constant relevant at a cosmological redshift of z ~ 15-20.Comment: 14 pages, 12 figure

Principles and applications of CRISPR toolkit in virus manipulation, diagnosis, and virus-host interactions

Viruses are one of the most important concerns for human health, and overcoming viral infections is a worldwide challenge. However, researchers have been trying to manipulate viral genomes to overcome various disorders, including cancer, for vaccine development purposes. CRISPR (clustered regularly interspaced short palindromic repeats) is becoming one of the most functional and widely used tools for RNA and DNA manipulation in multiple organisms. This approach has provided an unprecedented opportunity for creating simple, inexpensive, specific, targeted, accurate, and practical manipulations of viruses, such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), human immunodeficiency virus-1 (HIV-1), and vaccinia virus. Furthermore, this method can be used to make an effective and precise diagnosis of viral infections. Nevertheless, a valid and scientifically designed CRISPR system is critical to make more effective and accurate changes in viruses. In this review, we have focused on the best and the most effective ways to design sgRNA, gene knock-in(s), and gene knock-out(s) for virus-targeted manipulation. Furthermore, we have emphasized the application of CRISPR technology in virus diagnosis and in finding significant genes involved in virus-host interactions

HSP90 inhibitor, celastrol, arrests human monocytic leukemia cell U937 at G0/G1 in thiol-containing agents reversible way

<p>Abstract</p> <p>Background</p> <p>Because some of heat shock protein 90's (HSP90) clients are key cell cycle regulators, HSP90 inhibition can affect the cell cycle. Recently, celastrol is identified both as a novel inhibitor of HSP90 and as a potential anti-tumor agent. However, this agent's effects on the cell cycle are rarely investigated. In this study, we observed the effects of celastrol on the human monocytic leukemia cell line U937 cell cycle.</p> <p>Results</p> <p>Celastrol affected the proliferation of U937 in a dose-dependent way, arresting the cell cycle at G0/G1 with 400 nM doses and triggering cell death with doses above 1000 nM. Cell cycle arrest was accompanied by inhibition of HSP90 ATPase activity and elevation in HSP70 levels (a biochemical hallmark of HSP90 inhibition), a reduction in Cyclin D1, Cdk4 and Cdk6 levels, and a disruption of the HSP90/Cdc37/Cdk4 complex. The observed effects of celastrol on the U937 cell cycle were thiol-related, firstly because the effects could be countered by pre-loading thiol-containing agents and secondly because celastrol and thiol-containing agents could react with each other to form new compounds.</p> <p>Conclusions</p> <p>Our results disclose a novel action of celastrol-- causing cell cycle arrest at G0/G1 phase based upon thiol-related HSP90 inhibition. Our work suggests celastrol's potential in tumor and monocyte-related disease management.</p

Les progéniteurs endothéliaux circulants, utilisation potentielle en thérapie cellulaire de l'ischémie

La découverte de précurseurs circulants des cellules endothéliales (PEC) chez l'homme adulte a révolutionné le concept d'angiogenèse post-natale. De nombreux travaux sont venus confirmer l'existence des PEC, leur origine médullaire et leur aptitude à s'intégrer dans des structures vasculaires dans des sites de néoangiogenèse. Ils suggèrent que les PEC sont naturellement impliqués dans la prévention de l'ischémie en participant directement à l'angiogenèse de réparation. De par leur tropisme pour les sites de néoangiogenèse, les PEC constituent un outil thérapeutique dans la prévention ou la régression de l'ischémie, et une alternative à l'injection locale de facteurs proangiogéniques tels que le VEGF, qui comporte des risques. L'utilité de la transplantation autologue de cellules d'origine médullaire a été confirmée récemment par les premières études cliniques, qui montrent que des cellules mononucléées médullaires injectées à des patients souffrant d'ischémie des membres inférieurs ou cardiaque améliorent la reperfusion des tissus ischémiques. Cependant il s'agit d'études pionnières, réalisées sur un faible nombre de patients, elles utilisent des populations de cellules peu purifiées et ces essais ne sont pas randomisés. Elles posent cependant des questions importantes, notamment sur l'opportunité de purifier les cellules injectées, et sur la nature des cellules médullaires réellement impliquées dans la régénération vasculaire. Des études supplémentaires sont cependant nécessaires pour améliorer le produit de thérapie cellulaire. Il faudrait utiliser des populations de cellules plus homogènes, valider sur le long terme le bénéfice du traitement et explorer de façon extensive tous les effets secondaires possibles

Microenvironnement hématopoïétique du foie foetal (caractérisation et relation avec les cellules souches mésenchymateuses)

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF

Les progéniteurs endothéliaux et hépatiques (leurs intéractions et leurs potentiels thérapeutiques)

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF

Modèle de différenciation de cellules endothéliales à partir des cellules souches embryonnaires humaines

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF