No abstract

Coronaviruses are a large group of RNA viruses, the most notable representatives of which are SARS-CoV, MERS-CoV and SARS-CoV-2. Human coronavirus infections were first documented in the 1960s, when members causing seasonal common colds were successfully replicated in human embryonal trachea and kidney cell cultures and classified based on electron microscopy. The history of coronaviruses stretched far back to that point, however, with some representatives causing disease in animals identified several decades prior and evolutionary data pointing towards the origin of this viral group more than 55 million years ago. In the short time period of research since they were discovered, coronaviruses have shown significant diversity, genetic peculiarities and varying tropism, resulting in the three identified causative agents of severe disease in humans—SARS, MERS and the most recent one, COVID-19, which has surpassed the previous two due to causing a pandemic resulting in significant healthcare, social and political consequences. Coronaviruses are likely to have caused pandemics long before, such as the so-called Asian or Russian influenza. Despite being epitheliotropic viruses and predominantly affecting the respiratory system, these entities affect multiple systems and organs, including the kidneys. In the kidneys, they actively replicate in glomerular podocytes and epithelial cells of the tubules, resulting in acute kidney injury, seen in a significant percentage of severe and fatal cases. Furthermore, the endothelial affinity of the viruses, resulting in endotheliitis, increases the likelihood of thrombotic microangiopathy, damaging the kidneys in a two-hit mechanism. As such, recently, COVAN has been a suggested nomenclature change indicating renal involvement in coronavirus infections and its long-lasting consequences.

Liquid biopsies have emerged as a minimally invasive cancer detection and monitoring method, which could identify cancer-related alterations in nucleosome or histone levels and modifications in blood, saliva, and urine. Histones, the core component of the nucleosome, are essential for chromatin compaction and gene expression modulation. Increasing evidence suggests that circulating histones and histone complexes, originating from cell death or immune cell activation, could act as promising biomarkers for cancer detection and management. In this review, we provide an overview of circulating histones as a powerful liquid biopsy approach and methods for their detection. We highlight current knowledge on circulating histones in hematologic malignancies and solid cancer, with a focus on their role in cancer dissemination, monitoring, and tumorigenesis. Last, we describe recently developed strategies to identify cancer tissue-of-origin in blood plasma based on nucleosome positioning, inferred from nucleosomal DNA fragmentation footprint, which is independent of the genetic landscape.

SARS-CoV-2, a member of the betacoronavirus group and causative agent of COVID-19, is a virus affecting multiple systems, not only the respiratory. One of the systems affected by the virus is the central nervous system, with neuropathological studies reporting a wide set of morphological phenomena—neuroinflammation, vascular and blood-brain barrier alterations, neurodegeneration, and accelerated aging, while contradicting data is present on the direct neuroinvasive potential of the virus and active viral replication within neurons. The depicted changes, other than an acute effect (which may contribute to the death of the patient) also have chronic sequelae in the context of post-COVID syndrome cognitive impediments, sleep, and mood disorders. The following chapter describe the basic neuropathological aspects of SARS-CoV-2 as based on the present evidence in scientific literature and propose the term COVEP—COVID-associated encephalopathy—to unite the undisputed effects of the infection on nervous system morphology and function.

Apelin, a peptide initially isolated from bovine stomach extract, is an endogenous ligand for the Apelin Receptor (APLNR). Subsequently, a second peptide, ELABELA, that can bind to the receptor has been identified. The Apelin receptor and its endogenous ligands are widely distributed in mammalian organs. A growing body of evidence suggests that this system participates in various signaling cascades that can regulate cell proliferation, blood pressure, fluid homeostasis, feeding behavior, and pituitary hormone release. Additional research has been done to elucidate the system’s potential role in neurogenesis, the pathophysiology of Glioblastoma multiforme, and the protective effects of apelin peptides on some neurological and psychiatric disorders-ischemic stroke, epilepsy, Parkinson’s, and Alzheimer’s disease. This review discusses the current knowledge on the apelinergic system’s involvement in brain physiology in health and disease.