Multiblock copolymers, composed of different combinations and number of blocks, offer appreciable opportunities for new advanced materials. However, exploring this parameter space using traditional block copolymer synthetic techniques, such as living polymerization of sequential blocks, is time-consuming and requires stringent conditions. Using thiol addition across norbornene chemistry, we demonstrate a simple synthetic approach to multiblock copolymers that produces either random or alternating architectures, depending on the choice of reactants. Past reports have highlighted the challenges associated with using thiol−ene chemistry for polymer−polymer conjugation; however, using norbornene as the "ene" yielded multiblock copolymers at least four or five blocks. Preparation of new multiblock copolymers containing two or three block chemistries highlights the versatility of this new approach. These materials were thermally stable and showed microphase separation according to characterization by DSC, SAXS, and AFM. This chemical platform offers a facile and efficient route to exploring the many possibilities of multiblock copolymers.

Variants and homologs of bovine pancreatic ribonuclease (RNase A) can exhibit cytotoxic activity. This toxicity relies on cellular internalization of the enzyme. Residues Glu49 and Asp53 form an anionic patch on the surface of RNase A. We find that replacing these two residues with arginine does not affect catalytic activity or affinity for the cytosolic ribonuclease inhibitor (RI) protein. This 'arginine graft' does, however, increase toxicity towards human cancer cells. Appending a nonaarginine domain to this cationic variant results in an additional increase in cytotoxicity, providing one of the most cytotoxic known variants of RNase A. These findings correlate the potency of a ribonuclease with its deliverance of ribonucleolytic activity to the cytosol, and indicate a rational means to enhance the efficacy of ribonucleases and other cytotoxic proteins.

It is unclear if there is an association between COVID‐19 and cryptococcosis. Therefore, this study aimed to describe the clinical features, risk factors, and outcomes associated with cryptococcosis in hospitalised patients with COVID‐19. The objectives of this study were to determine the incidence of and examine factors associated with cryptococcosis after a diagnosis of COVID‐19. We used TriNetX to identify and sort patients 18 years and older hospitalised with COVID‐19 into two cohorts based on the presence or absence of a diagnosis of cryptococcosis following diagnosis of COVID‐19. Outcomes of interest included the incidence of cryptococcosis following the diagnosis of COVID‐19 as well as the proportion of patients in each group who had underlying comorbidities, received immunomodulatory therapy, required ICU admission or mechanical ventilation (MV), or died. Propensity score matching was used to adjust for confounding. Among 212,479 hospitalised patients with COVID‐19, 65 developed cryptococcosis. The incidence of cryptococcosis following COVID‐19 was 0.022%. Patients with cryptococcosis were more likely to be male and have underlying comorbidities. Among cases, 32% were people with HIV. Patients with cryptococcosis were more likely to have received tocilizumab (p < .0001) or baricitinib (p < .0001), but not dexamethasone (p = .0840). ICU admission (38% vs 29%), MV (23% vs 11%), and mortality (36% vs 14%) were significantly higher among patients with cryptococcosis. Mortality remained elevated after adjusted propensity score matching. Cryptococcosis occurred most often in hospitalised patients with COVID‐19 who had traditional risk factors, comparable to findings in patients without COVID‐19. Cryptococcosis was associated with increased ICU admission, MV, and mortality.

SARS-CoV-2 may activate both innate and adaptive immune responses ultimately leading to a dysregulated immune response prompting the use of immunomodulatory therapy. Although viral pneumonia increases the risk of invasive fungal infections, it remains unclear whether SARS-CoV-2 infection, immunomodulatory therapy, or a combination of both are responsible for the increased recognition of opportunistic infections in COVID-19 patients. Cases of cryptococcosis have previously been reported following treatment with corticosteroids, interleukin (IL)-6 inhibitors, and Janus kinase (JAK) inhibitors, for patients with autoimmune diseases, but their effect on the immunologic response in patients with COVID-19 remains unknown. Herein, we present the case of a patient with COVID-19 who received high-dose corticosteroids and was later found to have cryptococcosis despite no traditional risk factors. As our case and previous cases of cryptococcosis in patients with COVID-19 demonstrate, clinicians must be suspicious of cryptococcosis in COVID-19 patients who clinically deteriorate following treatment with immunomodulatory therapies.

Haloalkane dehalogenase (HD) catalyzes the hydrolysis of haloalkanes via a covalent enzyme–substrate intermediate. Fusing a target protein to an HD variant that cannot hydrolyze the intermediate enables labeling of the target protein with a haloalkane in cellulo. The utility of extant probes is hampered, however, by background fluorescence as well as limited membrane permeability. Here, we report on the synthesis and use of a fluorogenic affinity label that, after unmasking by an intracellular esterase, labels an HD variant in cellulo. Labeling is rapid and specific, as expected from the reliance upon enzymic catalysts and the high membrane permeance of the probe both before and after unmasking. Most notably, even high concentrations of the fluorogenic affinity label cause minimal background fluorescence without a need to wash the cells. We envision that such fluorogenic affinity labels, which enlist catalysis by two cellular enzymes, will find utility in pulse–chase experiments, high-content screening, and numerous other protocols.