Structure of a DNA G-quadruplex that Modulates SP1 Binding Sites Architecture in HIV-1 Promoter.

Nucleic acid sequences containing guanine tracts are able to form non-canonical DNA or RNA structures known as G-quadruplexes (or G4s). These structures, based on the stacking of G-tetrads, are involved in various biological processes such as gene expression regulation. Here, we investigated a G4 forming sequence, HIVpro2, derived from the HIV-1 promoter.

Structural Perspective into the Interaction of an Oncogenesis-Relevant pre-miRNA G-Quadruplex Ligand Carrier with the Protein Nucleolin.

The structural determinants of the interaction of the G-quadruplex (G4) motif found in precursor miRNA 149 (rG4) with the acridine orange derivative C , a G4 ligand stabilizer possessing anticancer activity, and the protein nucleolin (overexpressed in cancer cells) were investigated by Nuclear Magnetic Resonance (NMR) spectroscopy. For the rG4/C complex, the results revealed a strong stabilizing interaction between the aromatic core and the iodinated ring of the C ligand with the rG4 structure. The NMR study revealed also different interaction patterns between nucleolin and rG4 and nucleolin and rG4/C complex.

Guidelines for G-quadruplexes: I. In vitro characterization.

Besides the well-known DNA double-helix, non-canonical nucleic acid structures regulate crucial biological activities. Among these oddities, guanine-rich DNA sequences can form unusual four-stranded secondary structures called G-quadruplexes (G4s). G4-prone sequences have been found in the genomes of most species, and G4s play important roles in essential processes such as transcription, replication, genome integrity and epigenetic regulation.

RNA G-quadruplex forming regions from SARS-2, SARS-1 and MERS coronoviruses.

COVID-19 (Corona Virus Disease 2019), SARS (Severe Acute Respiratory Syndrome) and MERS (Middle East Respiratory Syndrome) are infectious diseases each caused by coronavirus outbreaks. Small molecules and other therapeutics are rapidly being developed to treat these diseases, but the threat of new variants and outbreaks argue for the identification of additional viral targets. Here we identify regions in each of the three coronavirus genomes that are able to form G-quadruplex (G4) structures.

Deciphering RNA G-quadruplex function during the early steps of HIV-1 infection.

G-quadruplexes (G4s) are four-stranded nucleic acid structures formed by the stacking of G-tetrads. Here we investigated their formation and function during HIV-1 infection. Using bioinformatics and biophysics analyses we first searched for evolutionary conserved G4-forming sequences in HIV-1 genome.

Schistosomiasis and Recurrent Arthritis: A Systematic Review of the Literature.

Background: Schistosomiasis is an endemic parasitic infection found in many tropical countries and is highly prevalent in sub-Saharan Africa. It can follow different and atypical clinical patterns. In these unusual cases, diagnosis may be difficult, as symptoms are unspecific.

Replication stress impairs chromosome segregation and preimplantation development in human embryos.

Human cleavage-stage embryos frequently acquire chromosomal aneuploidies during mitosis due to unknown mechanisms. Here, we show that S phase at the 1-cell stage shows replication fork stalling, low fork speed, and DNA synthesis extending into G2 phase. DNA damage foci consistent with collapsed replication forks, DSBs, and incomplete replication form in G2 in an ATR- and MRE11-dependent manner, followed by spontaneous chromosome breakage and segmental aneuploidies.

G-quadruplex structure of the C. elegans telomeric repeat: a two tetrads basket type conformation stabilized by a non-canonical C-T base-pair.

The Caenorhabditis elegans model has greatly contributed to the understanding of the role of G-quadruplexes in genomic instability. The GGCTTA repeats of the C. elegans telomeres resemble the GGGTTA repeats of the human telomeres.

High Salt Levels Reduced Dissimilarities in Root-Associated Microbiomes of Two Barley Genotypes.

Plants harbor in and at their roots bacterial microbiomes that contribute to their health and fitness. The microbiome composition is controlled by the environment and plant genotype. Previously, it was shown that the plant genotype-dependent dissimilarity of root microbiome composition of different species becomes smaller under drought stress.

Early combination therapy with hydroxychloroquine and azithromycin reduces mortality in 10,429 COVID-19 outpatients.

We evaluated the age-specific mortality of unselected adult outpatients infected with SARS-CoV-2 treated early in a dedicated COVID-19 day hospital and we assessed whether the use of hydroxychloroquine (HCQ) + azithromycin (AZ) was associated with improved survival in this cohort. A retrospective monocentric cohort study was conducted in the day hospital of our center from March to December 2020 in adults with PCR-proven infection who were treated as outpatients with a standardized protocol. The primary endpoint was 6-week mortality, and secondary endpoints were transfer to the intensive care unit and hospitalization rate.

The beginning and the end: flanking nucleotides induce a parallel G-quadruplex topology.

Genomic sequences susceptible to form G-quadruplexes (G4s) are always flanked by other nucleotides, but G4 formation in vitro is generally studied with short synthetic DNA or RNA oligonucleotides, for which bases adjacent to the G4 core are often omitted. Herein, we systematically studied the effects of flanking nucleotides on structural polymorphism of 371 different oligodeoxynucleotides that adopt intramolecular G4 structures. We found out that the addition of nucleotides favors the formation of a parallel fold, defined as the 'flanking effect' in this work.

Gold(III) porphyrins: Synthesis and interaction with G-quadruplex DNA.

G-quadruplex nucleic acids (G4s) are RNA and DNA secondary structures involved in the regulation of multiple key biological processes. They can be found in telomeres, oncogene promoters, RNAs, but also in viral genomes. Due to their unique structural features, very distinct from the canonical duplexes or single-strands, G4s represent promising pharmacological targets for small molecules, namely G4-ligands.

SARS-CoV-2 Persistent Viral Shedding in the Context of Hydroxychloroquine-Azithromycin Treatment.

SARS-CoV-2 nasopharyngeal shedding contributes to the spread of the COVID-19 epidemic. Among 3271 COVID-19 patients treated at the Hospital University Institute Méditerranée Infection, Marseille, France from 3 March to 27 April 2020, tested at least twice by qRT-PCR, the median SARS-CoV-2 nasopharyngeal shedding duration was 6 days (range 2-54 days). Compared with short shedders (qRT-PCR positivity < 10 days), 34 (1.

High-flow oxygen therapy in elderly patients infected with SARS-CoV2 with a contraindication for transfer to an intensive care unit: A preliminary report.

Objectives: In a conventional hospital ward, we used high-flow nasal oxygen (HFNO) to treat elderly COVID-19 patients noneligible for intensive care unit transfer.

Methods: This study was conducted in the Institut Hospitalo-Universitaire Méditerranée Infection, Assistance Publique-Hôpitaux de Marseille (AP-HM), France. We used high-flow nasal oxygen (HFNO) in our conventional infectious disease ward from 15 September 2020 for elderly patients noneligible for intensive care unit transfer.

Thermal and pH Stabilities of i-DNA: Confronting in vitro Experiments with Models and In-Cell NMR Data.

Recent studies indicate that i-DNA, a four-stranded cytosine-rich DNA also known as the i-motif, is actually formed in vivo; however, a systematic study on sequence effects on stability has been missing. Herein, an unprecedented number of different sequences (271) bearing four runs of 3-6 cytosines with different spacer lengths has been tested. While i-DNA stability is nearly independent on total spacer length, the central spacer plays a special role on stability.

Asymptomatic hypoxia in COVID-19 is associated with poor outcome.

Objectives: Describe and evaluate the outcome of a coronavirus disease-2019 (COVID-19) patient without shortness of breath.

Design And Methods: We retrospectively collected data from COVID-19 patients diagnosed and cared for in Marseille, France. We selected data from patients who at admission, had a low dose CT scanner, dyspnea status, and oxygen saturation available.

Dengue Virus Type 1 Infection in Traveler Returning from Benin to France, 2019.

We investigated a case of dengue virus type 1 infection acquired in Benin. Phylogenetic analysis revealed the strain belongs to genotype V but clusters with Asian, rather than with known African, strains. Our finding suggests the introduction of Asian dengue virus in West Africa.

Campylobacter jejuni infection associated with miscarriage, a case report and literature review.

Campylobacter jejuni is recognized as a cause of miscarriage in animals, but rarely in humans. We describe here a case of spontaneous miscarriage at 12 weeks of gestation associated with Campylobacter jejuni bacteremia following digestive disorders. The patient was treated with azithromycin with good clinical evolution and underwent uterine aspiration during hospitalization.

Child with liver transplant recovers from COVID-19 infection. A case report.

We present the case of a 55-month-old girl who recovered from coronavirus disease 2019 (COVID-19) infection 5 months after undergoing liver transplantation; she had a co-infection with Epstein-Barr virus (EBV). To the best of our knowledge, this is the first case report of a COVID-19 infection in a pediatric patient with liver transplantation. Additionally, this is also the first report of confirmed co-infection between COVID-19 and EBV.

Early treatment of COVID-19 patients with hydroxychloroquine and azithromycin: A retrospective analysis of 1061 cases in Marseille, France.

Background: In France, the combination hydroxychloroquine (HCQ) and azithromycin (AZ) is used in the treatment of COVID-19.

Methods: We retrospectively report on 1061 SARS-CoV-2 positive tested patients treated for at least three days with the following regimen: HCQ (200 mg three times daily for ten days) + AZ (500 mg on day 1 followed by 250 mg daily for the next four days). Outcomes were death, clinical worsening (transfer to ICU, and >10 day hospitalization) and viral shedding persistence (>10 days).

Clinical and microbiological effect of a combination of hydroxychloroquine and azithromycin in 80 COVID-19 patients with at least a six-day follow up: A pilot observational study.

Background: We need an effective treatment to cure COVID-19 patients and to decrease virus carriage duration.

Methods: We conducted an uncontrolled, non-comparative, observational study in a cohort of 80 relatively mildly infected inpatients treated with a combination of hydroxychloroquine and azithromycin over a period of at least three days, with three main measurements: clinical outcome, contagiousness as assessed by PCR and culture, and length of stay in infectious disease unit (IDU).

Results: All patients improved clinically except one 86 year-old patient who died, and one 74 year-old patient still in intensive care.