Recombinant bacterial cells as efficient biocatalysts for the production of nucleosides

The preparation of nucleosides as well as their base-modified analogues using purified nucleoside phosphorylase enzymes or, more conveniently, using whole bacterial cells is described. The development of genetically modified strains of Escherichia coli, able to over-produce Uridine-phosphorylase and Purine-nucleoside-phosphorylase in the same cells, improves the specific biocatalytic activity and the consequent industrial scale approach

Expression of phage P4 integrase is negatively regulated by both Int and Vis

Phage P4 int gene encodes the integrase responsible for phage integration into and excision from the Escherichia coli chromosome. Here, the data showing that P4 int expression is regulated in a complex manner at different levels are presented. First of all, the Pint promoter is regulated negatively by both Int and Vis, the P4 excisionase. The N-terminal portion of Int appears to be sufficient for such a negative autoregulation, suggesting that the Int N terminus is implicated in DNA binding. Second, full-length transcripts covering the entire int gene could be detected only upon P4 infection, whereas in P4 lysogens only short 59-end covering transcripts were detectable. On the other hand, transcripts covering the 59-end of int were also very abundant upon infection. It thus appears that premature transcription termination and/or mRNA degradation play a role in Int-negative regulation both on the basal prophage transcription and upon infection. Finally,comparison between Pint\u2013lacZ transcriptional and translational fusions suggests that Vis regulates Int expression post-transcriptionally. The findings that Vis is also an RNA-binding protein and that Int may be translated from two different start codons have implications on possible regulation models of Int expression

Isolated olfactory cleft involvement in SARS-CoV-2 infection: prevalence and clinical correlates

Purpose: Smell alterations are a symptom of COVID-19 and have been associated with olfactory cleft mucosal thickening (OCMT). Although their pathogenesis is unclear, evidences link them to viral neuroinvasive potential. This study aims at estimating the prevalence of OCMT in CT scans of COVID-19 patients and investigating its clinical correlates. Methods: In a single-institution retrospective cross-sectional study, we included all patients hospitalized for COVID-19 undergoing head CT scan for any reason. Exclusion criteria were history of recent head trauma or chronic rhinosinusitis; opacification > 2 mm in any sinonasal space other than the olfactory cleft; CT performed during/after invasive ventilation or feeding via nasogastric tube. We recorded the prevalence of OCMT and related it to age, sex, need for invasive ventilation during hospital stay, outcome, length of hospital stay, diffusion of lung SARS-CoV-19 lesions and outcome. Results: 63 eligible patients were identified (39 male, 24 female; median age 77.82 \ub1 17.77 years). OCMT was identified in 16 patients (25.4%; 95% CI 15.3-37.9%). Patients with OCMT had longer hospital stays (median 16 \ub1 4 vs. 9 \ub1 14.5 days, p = .009, Mann-Whitney U test) and required invasive ventilation more frequently than patients without mucosal thickening (OR 4.89, 95% CI 0.96-24.89, p = .063, Fisher's test). No other difference was observed. Conclusion: OCMT affects nearly one in four patients hospitalized for COVID-19. It is associated with a worse disease course irrespective of age, sex and diffusion of lung lesions, although with no direct effect on survival