Local and systemic responses to SARS-CoV-2 infection in children and adults

It is not fully understood why COVID-19 is typically milder in children1-3. Here, to examine the differences between children and adults in their response to SARS-CoV-2 infection, we analysed paediatric and adult patients with COVID-19 as well as healthy control individuals (total n = 93) using single-cell multi-omic profiling of matched nasal, tracheal, bronchial and blood samples. In the airways of healthy paediatric individuals, we observed cells that were already in an interferon-activated state, which after SARS-CoV-2 infection was further induced especially in airway immune cells. We postulate that higher paediatric innate interferon responses restrict viral replication and disease progression. The systemic response in children was characterized by increases in naive lymphocytes and a depletion of natural killer cells, whereas, in adults, cytotoxic T cells and interferon-stimulated subpopulations were significantly increased. We provide evidence that dendritic cells initiate interferon signalling in early infection, and identify epithelial cell states associated with COVID-19 and age. Our matching nasal and blood data show a strong interferon response in the airways with the induction of systemic interferon-stimulated populations, which were substantially reduced in paediatric patients. Together, we provide several mechanisms that explain the milder clinical syndrome observed in children.

Attentional salience and the neural substrates of response inhibition in borderline personality disorder

BACKGROUND

Impulsivity is a central symptom of borderline personality disorder (BPD) and its neural basis may be instantiated in a frontoparietal network involved in response inhibition. However, research has yet to determine whether neural activation differences in BPD associated with response inhibition are attributed to attentional saliency, which is subserved by a partially overlapping network of brain regions.

METHODS

Patients with BPD (n = 45) and 29 healthy controls (HCs; n = 29) underwent functional magnetic resonance imaging while completing a novel go/no-go task with infrequent odd-ball trials to control for attentional saliency. Contrasts reflecting a combination of response inhibition and attentional saliency (no-go > go), saliency processing alone (oddball > go), and response inhibition controlling for attentional saliency (no-go > oddball) were compared between BPD and HC.

RESULTS

Compared to HC, BPD showed less activation in the combined no-go > go contrast in the right posterior inferior and middle-frontal gyri, and less activation for oddball > go in left-hemispheric inferior frontal junction, frontal pole, superior parietal lobe, and supramarginal gyri. Crucially, BPD and HC showed no activation differences for the no-go > oddball contrast. In BPD, higher vlPFC activation for no-go > go was correlated with greater self-rated BPD symptoms, whereas lower vlPFC activation for oddball > go was associated with greater self-rated attentional impulsivity.

CONCLUSIONS

Patients with BPD show frontoparietal disruptions related to the combination of response inhibition and attentional saliency or saliency alone, but no specific response inhibition neural activation difference when attentional saliency is controlled. The findings suggest a neural dysfunction in BPD underlying attention to salient or infrequent stimuli, which is supported by a negative correlation with self-rated impulsiveness.

Using non-nutritive sucking to support feeding development for premature infants: A commentary on approaches and current practice

Non-nutritive sucking is often used with premature infants by either using a pacifier or an expressed breast nipple to support the introduction and development of early oral feeding. The pattern of non-nutritive sucking is distinct in that it involves two sucks per second in contrast to nutritive sucking which is one suck per second. Although some literature has identified that non-nutritive sucking has some benefit for the premature infant's feeding development, it is not entirely clear why such an approach is helpful as neurologically, activation of non-nutritive and nutritive skills are different. A summary is presented of the main approaches that use non-nutritive sucking with reference to the literature. This paper also considers other factors and beneficial approaches to managing the introduction of infant feeding. These are: the infant's toleration of enteral feeds pre oral trials, overall development and gestational age when introducing oral experiences, developing swallowing skills before sucking, physiological stability, health status, as well as the development and interpretation of infant oral readiness signs and early communication.

Blood flow in the common carotid artery in term and preterm infants: reproducibility and relation to cardiac output

AIM

To assess the reproducibility of, and determine normative data for, flow volume measurements from the right common carotid artery (CCA) and its relation to left ventricular output (LVO) in stable term and preterm babies using Doppler ultrasound.

METHODS

Right CCA flow volume was measured using a near focus, high frequency transducer by obtaining intensity weighted mean velocity and right CCA diameter. LVO was determined using standard Doppler techniques. Reproducibility studies were performed on 30 newborn infants by two observers. Normative data were obtained from 40 spontaneously breathing preterm babies and 21 term babies.

RESULTS

The intraobserver coefficient of variation for CCA flow measurements was 10.5% for observer 1 and 15.4% for observer 2, whereas the interobserver coefficient of variation was 16.4%. In term and preterm infants, right CCA flow was about 20 ml/kg/min, accounting for 11% of cardiac output. Among the preterm infants, there was a positive correlation of right CCA flow with gestation (r = 0.61, p<0.001), weight (r = 0.64, p<0.001), and LVO (r = 0.59, p<0.001). Right CCA diameter also increased with weight (r = 0.63, p<0.001) and gestation (r = 0.58, p<0.001). The proportion of LVO distributed to the right CCA did not increase with gestation, nor did the right CCA flow per kg body weight.

CONCLUSIONS

It is possible to perform reproducible measurements of flow volume in the CCA of newborn infants. In stable, spontaneously breathing babies, both cardiac output and carotid flow increased with gestation and body weight. The proportion of cardiac output distributed to the right CCA remained relatively constant across gestation.

Intracellular stability of the gene encoding influenza virus haemagglutinin

The intracellular stability of the genome of noninfectious uv-irradiated influenza virus (A/WSN:H1N1) in dividing MDCK cells was investigated using marker rescue techniques. The haemagglutinin gene could still be rescued by infection with A/X49 (H3N2) at 5 weeks postinoculation; its half-life was 13 days.

Intracellular stability of the interfering activity of a defective interfering influenza virus in the absence of virus multiplication

Half-lives of the interfering activity of a human defective interfering (DI) influenza virus and of viral RNA in MDCK cells inoculated with noninfectious DI virus were 25 and 17 days, respectively, and of viral RNA in cells inoculated with noninfectious uv-irradiated standard virus was 21 days. In neither case was there evidence of virus replication (de novo synthesis of viral proteins, haemagglutinin, or infectivity). The half-life in BHK cells was shorter, although still considerable, showing evidence of a host contribution to stability. Implications of the putative persistence of influenza virus genes in vivo to the natural history of the virus are discussed.