Hyperactive immature state and differential CXCR2 expression of neutrophils in severe COVID-19

Neutrophils are vital in defence against pathogens, but excessive neutrophil activity can lead to tissue damage and promote acute respiratory distress syndrome. COVID-19 is associated with systemic expansion of immature neutrophils, but the functional consequences of this shift to immaturity are not understood. We used flow cytometry to investigate activity and phenotypic diversity of circulating neutrophils in acute and convalescent COVID-19 patients. First, we demonstrate hyperactivation of immature CD10^- subpopulations in severe disease, with elevated markers of secondary granule release. Partially activated immature neutrophils were detectable 12 wk post-hospitalisation, indicating long term myeloid dysregulation in convalescent COVID-19 patients. Second, we demonstrate that neutrophils from moderately ill patients down-regulate the chemokine receptor CXCR2, whereas neutrophils from severely ill individuals fail to do so, suggesting an altered ability for organ trafficking and a potential mechanism for induction of disease tolerance. CD10^- and CXCR2^hi neutrophil subpopulations were enriched in severe disease and may represent prognostic biomarkers for the identification of individuals at high risk of progressing to severe COVID-19.

Complications of Radiotherapy and Radiosurgery in the Brain and Spine

Radiation therapy is an integral part of the standard of care for many patients with brain and spine tumors. Stereotactic radiation surgery is increasingly being used as an adjuvant therapy as well as a sole treatment. However, despite newer and more focused techniques, radiation therapy still causes significant neurotoxicity. In this article, we reviewed the scientific literature, presented cases of patients who had developed different complications related to conventional radiation therapy or radiosurgery (gamma knife), demonstrated the imaging findings, and discussed the relevant clinical information for the correct diagnoses. Radiation therapy can cause injury in different ways: directly damaging the structures included in the radiation portal, indirectly affecting the blood vessels, and increasing the chance of tumor development. We also divided radiation complications according to the time of occurrence: acute (0 to 4 weeks), early delayed (4 weeks to months), and late delayed (months to years). With the increasing application of radiation therapy for the treatment of CNS tumors, it is important for the neuroradiologist to recognize the many possible complications of radiation therapy. Although this may cause significant diagnostic challenges, understanding the pathophysiology, time course of onset, and imaging features may help institute early therapy and prevent possible deleterious outcomes.

Learning Objectives

To recognize the main complications of radiation therapy and stereotactic radiosurgery in the brain and spine, and to highlight the imaging findings to improve the diagnostic process and treatment planning.

CT Angiography of the Head in Extracorporeal Membrane Oxygenation

Extracorporeal membrane oxygenation is an artificial cardiopulmonary bypass technique used to support patients with severe pulmonary failure or both pulmonary and cardiac failure. The hemodynamic changes produced by extracorporeal membrane oxygenation affect the appearance of CTA of the head images, often confounding interpretation if the correct history and understanding of extracorporeal membrane oxygenation are not known. This technical report describes the principles of extracorporeal membrane oxygenation, techniques to optimize intracranial CTA imaging, and pitfalls.

Integrin clustering mechanisms explored with a soluble αIIbβ3 ectodomain construct

The purpose of this study was to test the hypothesis that residues critical for ligand- and temperature-induced clustering of integrin alphaIIbbeta3 are present on its extracellular domain. Sucrose density gradient sedimentation was used to examine the effects of ligand-mimetic peptides and physiological temperature on the oligomeric state of a soluble recombinant ectodomain variant of the alphaIIbbeta3 integrin, alphaIIbDelta962beta3Delta692, and its full-length counterpart. Both the ectodomain construct, isolated from High Five insect cell culture supernatants, and alphaIIbbeta3, isolated from human blood platelets, exhibited similar weight-average sedimentation coefficients at 23 degrees C, in the absence and presence of the ligand-mimetic peptide eptifibatide. These observations indicate that alphaIIbbeta3's ectodomain exhibits a similar extended conformation in both its free and ligand-bound states. Oligomerization was examined by incubation of both alphaIIbDelta962beta3Delta692 and full-length receptors at 37 degrees C, in the presence or absence of ligand-mimetic. Minimal oligomerization was observed with alphaIIbDelta962beta3Delta692. In contrast, full-length alphaIIbbeta3 exhibited substantial temperature-induced increases in its distribution of sedimenting species, indicative of thermal aggregation. These observations suggest that optimum oligomerization requires the participation of the integrin's transmembrane and cytoplasmic regions. In vivo, clustering of ligand-bound integrins may enhance signaling by increasing the local concentration of intracellular integrin-associated proteins.

Dangers of defibrillation: injuries to emergency personnel during patient resuscitation

There have been no studies of the nature of defibrillatory shocks or risks to persons, providing them other than one individual case report and a number of incidental accounts. In this study, the severity and nature of injuries to prehospital emergency personnel in King County, Washington are reported. In addition, the types of injuries occurring to defibrillator operators throughout the United States, as voluntarily reported to the Food and Drug Administration (FDA), are described. In King County, prehospital emergency personnel reported eight accidental shocks. One individual was admitted to the hospital for 3 days and required lidocaine for premature ventricular contractions. Most injuries were the result of accidental contact with the patient rather than equipment failure, but the most serious case was caused by equipment failure. There were 13 injuries reported to the FDA over a 3 1/2-year period, and most injuries involved a mild shock or burn. Three patients were admitted to the hospital for observation. Two cases involved equipment failure. The rate of injury for paramedics was 1 per 1,700 defibrillatory shocks, and the rate of injury for emergency medical technician-defibrillator personnel was 1 per 1,000 defibrillatory shocks. These rates probably overestimate the real risk. Emphasis on safety and incorporation of safety procedures into resuscitation protocols can make the rate of injury even lower.

The great Australian drought: 1982-1983*

The development of drought over eastern Australia from April 1982 to February 1983 is described. National wheat production for the 1982-1983 season was 63 per cent of the average for the previous five years, while for New South Wales and Victoria production was 29 and 16 per cent respectively. Production of other grains was similarly reduced. Net value of rural production was reduced from over $4,000 million to $2,300 million nationally, the percentage reduction being much larger in drought-affected States. Methods of assessing drought severity are discussed and it is concluded that the 1982-1983 drought must be regarded as one of the most severe in the last 100 years. Impact of drought is also discussed, including that on wheat production and sheep and cattle populations since 1885. It is suggested that the limits of grain growing areas, and of sheep and cattle populations, beyond which environmental degradation may occur, have been exceeded during that period. The view is expressed that more attention should be given to the development of strategies to ameliorate drought impacts.

In vitro activation of bacteriophage P2 late gene expression by extracts from phage P4-infected cells

We have used a cell-free, DNA-dependent protein-synthesizing system to study the stimulation of phage P2 late gene expression by satellite phage P4. An activity is present in extracts prepared from P4-infected cells, which, when added to the in vitro system with P2 DNA template, stimulates the synthesis of a number of P2 proteins. These stimulated proteins include the major P2 capsid protein (N gene product) and a major component of the P2 phage tail (FII gene product). Extracts prepared from P4-infected cells are also able to stimulate the synthesis from P4 DNA of two low-molecular-weight proteins (18,500 and 17,000 Mr). The stimulating activity has no effect on the synthesis of proteins from lambda plac5 template. Extracts prepared from cells infected with P4 alpha amber mutants lack this stimulating activity.

Cerebellar macroneurons in microexplant cell culture. Methodology, basic electrophysiology, and morphology after horseradish peroxidase injection

Cerebellar macroneurons, including Purkinje cells, survive and differentiate in long-term monolayer cultures, which are prepared by a partial dissociation procedure we refer to as a microexplant technique. Intracellular recording demonstrated that these neurons were functional, showing spontaneous spiking activity and electrical excitability, and both spontaneous and evoked synaptic activity. In order to further characterize cell types, light and electron microscopic studies were performed after intracellular iontophoresis of horseradish peroxidase. Purkinje neurons were identified by their form of dendritic arborization and numerous dendritic spines. Cortical granule cells and macroneurons derived from the deep nuclei could also be demonstrated.

Kainic acid sensitivity of mammalian Purkinje cells in monolayer cultures

Purkinje cells from fetal mouse cerebellum were studied in a monolayer culture system. These neurons, labeled by intracellular iontophoresis of HRP, showed one or more thick, spine-covered dendrites and an axon whose swellings contacted other neuronal processes and Purkinje cell somata. In short-term experiments, kainic acid was cytotoxic to Purkinje neurons and not to granule cells in monolayer cultures of fetal rat cerebellum.

A transcribing activity induced by satellite phage P4

Satellite bacteriophage P4 induces a new transcribing enzyme that synthesizes polyriboguanylic acid in the presence of the poly(dG).poly(dC) homopolymer pair. This transcribing activity was partially purified and shown to be distinct from the host RNA polymerase. Analysis of conditional lethal mutants suggests that this new enzyme is necessary for replication of phage DNA.