Optical properties of individual CdS/CdSe/CdS nanocrystals: spherical quantum wells as single-photon sources

We have synthesized CdS(1.3 nm)/CdSe(1.7 nm)/CdS(3.4 nm) spherical quantum wells (SQWs) with a diameter of 13 nm and demonstrated the first photon-antibunching from their emission, labelling them as single-photon sources. Antibunching survives even at high excitation intensities, ruling-out strong emission from the bi-exciton. For the largest intensities, antibunching coupled to spectral measurements reveal the signature of a blue-shifted emission, associated to an irreversible photo-aging effect. A statistical analysis over 26 SQWs demonstrates a moderate correlation between the energy of the main and the blue-shifted emission. Intensity-timetraces recorded on 28 single SQWs show weak blinking, with a median time spent in the bright state of 89%. Their emission decay reveals a complex dynamic with either three or four exponential components. We assigned three of them to the neutral and singly-charged excitons and the slowest to defect emission. While SQWs have been initially designed for laser-oriented applications, we demonstrate that they can serve as efficient single-photon sources.

Émergence de variants E484 K suite à une monothérapie bamlanivimab chez des patients COVID-19 à haut risque d’évolution vers une forme sévère

Introduction

En France, une Autorisation d’Utilisation Temporaire de cohorte (ATUc) a été délivrée le 27/02/2021 pour l’utilisation du bamlanivimab en monothérapie dans le traitement précoce (< 5 jours du début des symptômes) de patients adultes avec un COVID-19 léger à modéré confirmé par PCR et à haut risque d’évolution vers une forme sévère. Les patients concernés étaient les patients de > 80 ans ou les patients de < 80 ans immunodéprimés (transplantation, chimiothérapie, traitement immunosuppresseur). Le risque d’émergence de variants potentiellement résistants à un monothérapie par anticorps monoclonal anti-Spike, en particulier les variants E484 K, avait été pris en compte lors de l’ATUc. Cependant, le bénéfice potentiel de ces traitements chez les patients à haut risque a été considéré comme supérieur au risque. Ici nous décrivons 6 patients ayant reçu de ce traitement, leur évolution et l’émergence de mutations de résistance sous pression de sélection.

Matériels et méthodes

Il s’agit d’une étude unicentrique en centre hospitalier universitaire. Le bamlanivimab a été administré à une dose unique de 700 mg en injection IV d’une heure chez 6 patients qui ont accepté d’utiliser le traitement dans le cadre de l’ATUc. Le suivi virologique des patients a consisté en un test RT-qPCR itératif réalisé le jour de la perfusion ou la veille, à J3 ± 1, à J5 ± 1, à J7 ± 1 puis tous les 3 jours jusqu’à ce que la PCR soit négative. La sélection de mutation de résistance a été vérifiée par séquençage du génome complet du SARS-CoV-2 chez tous les patients.

Résultats

Les six hommes traités avaient un âge médian de 65 ans (extrêmes 35-97), plus de 3 comorbidités à haut risque d’évolution vers une forme sévère et 5 étaient infectés par un variant UK (N501Y.V1, B.1.1.7). Le traitement a été administré dans les 4 jours suivant l’apparition des symptômes (médiane 2 jours). Les 6 patients ont eu une évolution clinique favorable, deux ont eu besoin d’oxygène au débit maximal de 4 L/min. Aucun patient n’a eu besoin d’oxygénothérapie haut débit, d’une ventilation non invasive ou d’une ventilation invasive. À J20 après l’administration, un seul présentait une PCR nasopharyngée négative et 5 présentaient l’apparition d’une mutation E484 K à différents moments après l’administration (J6, J7, J12, J14 et J26).

Conclusion

Chez ces patients à très haut risque d’évolution vers une forme sévère, la sélection de la mutation E484 K après administration de bamlanivimab en monothérapie était très fréquente et bien plus importante qu’observée dans les premiers essais cliniques. Ceci peut être expliqué en partie par l’infection par un variant UK pour 5/6 patients décrits ici. L’émergence de résistance lors des bithérapies devra être suivi attentivement, notamment avec l’émergence des nouveaux variants.

[Neonatal asphyxia: neurologic outcome]

AIM

The neonatal asphyxia is recognized as an important cause of morbidity and mortality during the pediatric age. The objective of this study was to evaluate the correlation between some neonatal variables and neurological outcome at two years of life in infants with asphyxia, in order to produce a correct prognosis and to grant a rapid and targeted therapy.

METHODS

We have recruited 63 patients whose history and neuroimages suggested a neonatal asphyxia, and we have analysed their clinical- instrumental parameters every three months until two years of life. A correlation study was carried out in order to find a statistical significance indicated by p-value < 0,05. The correlation was made by means of Chi-square and ANOVA (analysis of variance) test.

RESULTS

Only one patient developed isolated epilepsy, 17 developed CP associated to epilepsy (14 of them were term infants, 3 were preterm); 25 patients, 13 term and 12 preterm, developed only CP; 20 patients, 11 preterm and 9 term infants, developed a psychomotor delay. The most severe clinical picture (CP associated with epilepsy) appeared in 12 infants of adequate weight and in 5 LBW children; the CP appeared in 14 NW patients, 5 LBW, 4 VLBW and 2 ELBW. Psychomotor delay was developed by 8 NW children, 2 LBW and 10 ELBW. Most patients with severe CP presented severe neurological symptoms at birth. Moderate CP involved those who had a mild neurological or systemic symptoms. Furthermore an association emerged between early epilepsy and CP onset and their severity.

CONCLUSION

Neonatal seizures are not related to an increased risk to develop epilepsy. Epilepsy alone is a rare event and it usually complicates CP picture. Most subject with both epilepsy and CP are term infants with adequate weight. Preterm VLBW infants have a greater risk to develop a psychomotor delay. Clinical conditions at birth are related to CP severity (several neonatal neurological signs are the greater risk factors). Severely pathological neonatal EEG (background activity) is related to CP severity and an early symptomatic epilepsy onset is related with both epilepsy and CP severity.

Ethanolic extract of roots from Arctium lappa L. accelerates the healing of acetic acid-induced gastric ulcer in rats: Involvement of the antioxidant system

We evaluate the curative efficacy of the ethanolic extract (EET) of roots from Arctium lappa (bardana) in healing of chronic gastric ulcers induced by 80% acetic acid in rats and additionally studies the possible mechanisms underlying this action. Oral administration of EET (1, 3, 10 and 30mg/kg) reduced the gastric lesion area in 29.2%, 41.4%, 59.3% and 38.5%, respectively, and at 10mg/kg promoted significant regeneration of the gastric mucosa, which was confirmed by proliferating cell nuclear antigen immunohistochemistry. EET (10mg/kg) treatment did not increase the gastric mucus content but restored the superoxide dismutase activity, prevented the reduction of glutathione levels, reduced lipid hydroperoxides levels, inhibited the myeloperoxidase activity and reduced the microvascular permeability. In addition, EET reduced the free radical generation and increased scavenging of 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals in vitro. Furthermore, intraduodenal EET (10 and 30mg/kg) decreased volume and acidity of gastric secretion. Total phenolic compounds were high in EET (Folin-Ciocalteau assay) and the analysis by liquid chromatography-mass spectrometry revealed that the main compounds present in EET were a serie of hydroxycinnamoylquinic acid isomers. In conclusion, these data reveal that EET promotes regeneration of damaged gastric mucosa, probably through its antisecretory and antioxidative mechanisms.

[Procedural pain perception of preterm newborn in neonatal intensive care unit: assessment and non-pharmacological approaches]

AIM

The aim of this study was to evaluate the reaction to the procedural pain of preterm newborn and to demonstrate the different effectiveness of the two analgesic and not pharmacological techniques of recent clinical acquisition, the use of glucose solution and the sensorial saturation, in order to identify an optimal strategy for the prevention and pain treatment.

METHODS

We take a sample of 28 preterm newborns of 30-35 weeks. The subjects are divided in two randomized groups following the kind of analgesia used during the hematic sample from heel: the first group (group A) included 14 subjects, who received glucose solution associated to no nutritive suction; the second group (group B) included 14 subjects who received the sensorial saturation. The symptoms associated with pain at the moment of venous sample are measured through premature infant pain profile (PIPP) scale.

RESULTS

Results show that the score was lower in the group treated with sensorial saturation (media 6.52; P<0.001) than in the group treated with glucose (media 13.80; P<0.05).

CONCLUSION

The use of "care" techniques (in our case sensorial saturation) ameliorates the quality of life in NICU and reduces the pain threshold perceived by newborn, reducing therefore the exposition to the pain stimulus and the possibility that some consequences due to an inadequate pain treatment in neonatal age could develop.

Antiulcerogenic activity of hydroalcoholic extract of Achillea millefolium L.: involvement of the antioxidant system

Achillea millefolium L. is a member of the Asteraceae family that is commonly referred to as "yarrow" and has been used in folk medicine against several disturbances including skin inflammations, spasmodic and gastrointestinal disorders, as well as hepato-biliary complaints.

AIM OF THE STUDY

In the present study, we evaluated the efficacy of a hydroalcoholic extract from the Achillea millefolium (HE) for gastroprotective properties and additional mechanism(s) involved in this activity.

MATERIAL AND METHODS

Rats were treated with HE and subsequently exposed to both acute gastric lesions induced by ethanol P.A. and chronic gastric ulcers induced by 80% acetic acid. Following treatment, glutathione (GSH) levels and superoxide dismutase (SOD) activity were measured. The activity of myeloperoxidase (MPO) and histological and immunohistochemical analysis were performed in animals with acetic acid-induced gastric ulcers.

RESULTS

Oral administration of HE (30, 100 and 300mg/kg) inhibited ethanol-induced gastric lesions by 35, 56 and 81%, respectively. Oral treatment with HE (1 and 10mg/kg) reduced the chronic gastric ulcers induced by acetic acid by 43 and 65%, respectively, and promoted significant regeneration of the gastric mucosa after ulcer induction denoting increased cell proliferation, which was confirmed by PCNA immunohistochemistry. HE treatment prevented the reduction of GSH levels and SOD activity after acetic acid-induced gastric lesions. In addition, HE (10mg/kg) inhibited the MPO activity in acetic acid-induced gastric ulcers.

CONCLUSIONS

The results of the present study indicate that the antioxidant properties of HE may contribute to the gastroprotective activity of this extract.