Coronavirus disease 2019 (COVID-19) is a newly emerged disease with various clinical manifestations and imaging features. The diagnosis of COVID-19 depends on a positive nucleic acid amplification test by real-time reverse transcription-polymerase chain reaction (RT-PCR) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, the clinical manifestations and imaging features of COVID-19 are non-specific, and nucleic acid test for SARS-CoV-2 can have false-negative results. It is presently believed that detection of specific antibodies to SARS-CoV-2 is an effective screening and diagnostic indicator for SARS-CoV-2 infection. Thus, a combination of nucleic acid and specific antibody tests for SARS-CoV-2 will be more effective to diagnose COVID-19, especially to exclude suspected cases.

Aims: To identify subgroups of patients with squamous cell carcinoma (SCC) of the larynx, characterized by the specific deregulation mechanism of the epidermal growth factor receptor (EGFR) gene, and to evaluate EGFR protein expression levels and correlate these with biological and clinicopathological parameters.

Materials and methods: Using tissue microarray technology, 50 formalin-fixed, paraffin-embedded primary laryngeal SCCs were cored and re-embedded into one block. Immunohistochemistry and chromogenic in situ hybridization were performed.

Results: Epidermal growth factor receptor protein over-expression was observed in 27/50 (54 per cent) cases and was statistically associated with tumour grade (p=0.028). Epidermal growth factor receptor gene alterations were identified in 5/50 (10 per cent) cases, which demonstrated amplification (n=4) and deletion (n=1). Chromosome 7 instability was detected in 8/50 (16 per cent) cases.

Conclusions: Epidermal growth factor receptor over-expression is a frequent event in SCCs, but it does not predict a specific molecular mechanism of gene deregulation for targeted therapeutic strategies via monoclonal antibodies.

Template-directed polymer assembly is a likely feature of prebiotic chemistry, but the product blocks further synthesis, preventing amplification and Darwinian selection. Nucleic acids are unusual because charge repulsion between opposing phosphates permits salt-dependent association and dissociation. It was postulated (Lathe, R. (2004). Fast tidal cycling and the origin of life. Icarus168, 18–22) that tides at ocean shores provide the driving force for amplification: evaporative concentration promoted association/assembly on drying, while charge repulsion on tidal dilution drove dissociation. This permits exponential amplification by a process termed here the tidal chain reaction (TCR). The process is not strictly contingent upon tidal ebb and flow: circadian dews and rainfalls can produce identical cycling. Ionic strength-dependent association and dissociation of nucleic acids and possible prebiotic precursors are reviewed. Polymer scavenging, chain assembly by the recruitment of pre-formed fragments, is proposed as the primary mechanism of reiterative chain assembly. Parameters determining prebiotic polymer structure and amplification by TCR are discussed, with the suggestion that Darwinian selection may have operated on families of related polymers rather than on individual molecules.