A case of ileal caecum intussusception mimicking rectal prolapse in a 4-month-old female infant.

INTRODUCTION AND IMPORTANCE: Ilea caecum Intussusception protruding to the level of anus is a rare manifestation and potentially serious condition in infants. CASE PRESENTATION: A four-month-old infant presented with a one-day history of non-projectile vomiting, three episodes, food contents, worsened by feeding, accompanied by intermittent low-grade fever, and one instance of passing black tarry stool. After outpatient treatment, the infant showed improvement for three days, but later the mother noticed a protruding, self-reducing anal mass, hence the suspected rectal prolapse, which was then Referred for further management. CLINICAL DISCUSSION: Intussusception, the most frequent surgical emergency in infants and young children aged 3 to 6 months, is primarily idiopathic, with the ileocecal region being the most commonly affected (90 % of cases). However, when the intussusceptum advances to the anus, it's rare, often leading to misdiagnosis and mismanagement. CONCLUSION: Intussusception of the colon should be added to the differential diagnosis of symptoms and the clinical picture of rectal prolapse.

A glycan gate controls opening of the SARS-CoV-2 spike protein

SARS-CoV-2 infection is controlled by the opening of the spike protein receptor binding domain (RBD), which transitions from a glycan-shielded "down" to an exposed "up" state in order to bind the human ACE2 receptor and infect cells. While snapshots of the "up" and "down" states have been obtained by cryoEM and cryoET, details of the RBD opening transition evade experimental characterization. Here, over 130 s of weighted ensemble (WE) simulations of the fully glycosylated spike ectodomain allow us to characterize more than 300 continuous, kinetically unbiased RBD opening pathways. Together with ManifoldEM analysis of cryo-EM data and biolayer interferometry experiments, we reveal a gating role for the N-glycan at position N343, which facilitates RBD opening. Residues D405, R408, and D427 also participate. The atomic-level characterization of the glycosylated spike activation mechanism provided herein achieves a new high-water mark for ensemble pathway simulations and offers a foundation for understanding the fundamental mechanisms of SARS-CoV-2 viral entry and infection.