P29-A135 Impact of COVID-19 on corneal donation and transplantation in Hong Kong

PURPOSE

With many health and policy issues arising from COVID-19, the Hospital Authority Eye Bank of Hong Kong encountered challenges related to ocular donor suitability and availability. This review aims to analyse the impact of a global pandemic on corneal donation and transplantation in 2020 and 2021, compared to the pre-COVID period in 2019.

METHODS

This cohort study evaluated data collected from the Hospital Authority Eye Bank from January 2019 to December 2021. The number of corneas harvested, including voluntary donations initiated by the deceased's relatives and approached cases by Eye Donation Coordinators, tissue distributed, transplanted and disposed, the reason for disposal as well as the usage of the transplanted corneas in 2020 and 2021 were compared to the pre-COVID period of 2019.

RESULTS

The number of corneas harvested dropped by 17.6% in 2020 compared to the pre-COVID period of 2019, and rose almost back to baseline in 2021. However, despite having near-normal number of harvested corneas in 2021, the number of corneal transplants using fresh corneas were still reduced by 30% in 2020 and 27% 2021. The observation can be explained by the seven-fold increment in disposal due to suboptimal quality from a cancer donor in 2021. The proportion of corneas used for optical, therapeutic and tectonic purposes remained stable throughout the three years.

CONCLUSION

COVID-19 yielded brief periods of service interruption and reduced number of eligible donors, leading to a noticeable rise in solicitation from cancer donors in 2021. The pandemic resulted in a longer corneal transplant waiting time. Nevertheless, The proportion of different corneal transplantation remained stable, with even the development in new techniques such as Descemet's Membrane Endothelial Keratoplasty and enhancement in services such as provision of ultra-fresh Keratolimbal allografts despite the limitations in the COVID-19 era.

The NF-κB multidimer system model: A knowledge base to explore diverse biological contexts

The nuclear factor κB (NF-κB) system is critical for various biological functions in numerous cell types, including the inflammatory response, cell proliferation, survival, differentiation, and pathogenic responses. Each cell type is characterized by a subset of 15 NF-κB dimers whose activity is regulated in a stimulus-responsive manner. Numerous studies have produced different mathematical models that account for cell type-specific NF-κB activities. However, whereas the concentrations or abundances of NF-κB subunits may differ between cell types, the biochemical interactions that constitute the NF-κB signaling system do not. Here, we synthesized a consensus mathematical model of the NF-κB multidimer system, which could account for the cell type-specific repertoires of NF-κB dimers and their cell type-specific activation and cross-talk. Our review demonstrates that these distinct cell type-specific properties of NF-κB signaling can be explained largely as emergent effects of the cell type-specific expression of NF-κB monomers. The consensus systems model represents a knowledge base that may be used to gain insights into the control and function of NF-κB in diverse physiological and pathological scenarios and that describes a path for generating similar regulatory knowledge bases for other pleiotropic signaling systems.

Investigation of healthcare-associated SARS-CoV-2 infection: Learning outcomes from an investigative process in the initial phase of the pandemic

Background

Healthcare-associated (HCA) SARS-CoV-2 infection is a significant contributor to the spread of the 2020 pandemic. Timely review of HCA cases is essential to identify learning to inform infection prevention and control (IPC) policies and organisational response.

Aim

To identify key areas for improvement through rapid investigation of HCA SARS-CoV-2 cases and to implement change.

Methods

Cases were identified based on date of first positive SARS-CoV-2 PCR sample in relation to date of hospital admission. Cases were reviewed using a structured gap analysis tool to identify key learning points. These were discussed in weekly multidisciplinary meetings to gain consensus on learning outcomes, level of harm incurred by the patient and required actions. Learning was then promptly fed back to individual teams and the organisation.

Findings

Of the 489 SARS-CoV-2 cases admitted between 10^th March and 23^rd June 2020, 114 suspected HCA cases (23.3%) were reviewed; 58/489 (11.8%) were ultimately deemed to be HCA. Five themes were identified: individual patient vulnerability, communication, IPC implementation, policy issues and organisational response. Adaptations to policies based on these reviews were completed within the course of the initial phase of the pandemic.

Conclusion

This approach enabled timely learning and implementation of control measures and policy development.

Experiments from unfinished Registered Reports in the Reproducibility Project: Cancer Biology

As part of the Reproducibility Project: Cancer Biology, we published Registered Reports that described how we intended to replicate selected experiments from 29 high-impact preclinical cancer biology papers published between 2010 and 2012. Replication experiments were completed and Replication Studies reporting the results were submitted for 18 papers, of which 17 were accepted and published by eLife with the rejected paper posted as a preprint. Here, we report the status and outcomes obtained for the remaining 11 papers. Four papers initiated experimental work but were stopped without any experimental outcomes. Two papers resulted in incomplete outcomes due to unanticipated challenges when conducting the experiments. For the remaining five papers only some of the experiments were completed with the other experiments incomplete due to mundane technical or unanticipated methodological challenges. The experiments from these papers, along with the other experiments attempted as part of the Reproducibility Project: Cancer Biology, provides evidence about the challenges of repeating preclinical cancer biology experiments and the replicability of the completed experiments.

Replication study: androgen receptor splice variants determine taxane sensitivity in prostate cancer

In 2015, as part of the Prostate Cancer Foundation–Movember Foundation Reproducibility Initiative, we published a Registered Report (Shan et al., 2015) that described how we intended to replicate selected experiments from the paper “Androgen Receptor Splice Variants Determine Taxane Sensitivity in Prostate Cancer” (Thadani-Mulero et al., 2014). Here we report the results of those experiments. Growth of tumor xenografts from two prostate cancer xenograft lines, LuCaP 86.2, which expresses wild-type androgen receptor (AR) and AR variant 567, and LuCaP 23.1, which expresses wild-type AR and AR variant 7, were not affected by docetaxel treatment. The LuCaP 23.1 tumor xenografts grew slower than in the original study. This result is different from the original study, which reported significant reduction of tumor growth in the LuCaP 86.2. Furthermore, we were unable to detect ARv7 in the LuCaP 23.1, although we used the antibody as stated in the original study and ensured that it was detecting ARv7 via a known positive control (22rv1, Hörnberg et al., 2011). Finally, we report a meta-analysis of the result.

IκBβ enhances the generation of the low-affinity NFκB/RelA homodimer

The NFκB family of dimeric transcription factors regulate inflammatory and immune responses. While the dynamic control of NFκB dimer activity via the IκB-NFκB signalling module is well understood, there is little information on how specific dimer repertoires are generated from Rel family polypeptides. Here we report the iterative construction-guided by in vitro and in vivo experimentation-of a mathematical model of the Rel-NFκB generation module. Our study reveals that IκBβ has essential functions within the Rel-NFκB generation module, specifically for the RelA:RelA homodimer, which controls a subset of NFκB target genes. Our findings revise the current dogma of the three classical, functionally related IκB proteins by distinguishing between a positive 'licensing' factor (IκBβ) that contributes to determining the available NFκB dimer repertoire in a cell's steady state, and negative feedback regulators (IκBα and -ɛ) that determine the duration and dynamics of the cellular response to an inflammatory stimulus.

A pathway switch directs BAFF signaling to distinct NFκB transcription factors in maturing and proliferating B cells

BAFF, an activator of the noncanonical NFκB pathway, provides critical survival signals during B cell maturation and contributes to B cell proliferation. We found that the NFκB family member RelB is required ex vivo for B cell maturation, but cRel is required for proliferation. Combined molecular network modeling and experimentation revealed Nfkb2 p100 as a pathway switch; at moderate p100 synthesis rates in maturing B cells, BAFF fully utilizes p100 to generate the RelB:p52 dimer, whereas at high synthesis rates, p100 assembles into multimeric IκBsome complexes, which BAFF neutralizes in order to potentiate cRel activity and B cell expansion. Indeed, moderation of p100 expression or disruption of IκBsome assembly circumvented the BAFF requirement for full B cell expansion. Our studies emphasize the importance of p100 in determining distinct NFκB network states during B cell biology, which causes BAFF to have context-dependent functional consequences.

IκBε is a key regulator of B cell expansion by providing negative feedback on cRel and RelA in a stimulus-specific manner

The transcription factor NF-κB is a regulator of inflammatory and adaptive immune responses, yet only IκBα was shown to limit NF-κB activation and inflammatory responses. We investigated another negative feedback regulator, IκBε, in the regulation of B cell proliferation and survival. Loss of IκBε resulted in increased B cell proliferation and survival in response to both antigenic and innate stimulation. NF-κB activity was elevated during late-phase activation, but the dimer composition was stimulus specific. In response to IgM, cRel dimers were elevated in IκBε-deficient cells, yet in response to LPS, RelA dimers also were elevated. The corresponding dimer-specific sequences were found in the promoters of hyperactivated genes. Using a mathematical model of the NF-κB-signaling system in B cells, we demonstrated that kinetic considerations of IκB kinase-signaling input and IκBε's interactions with RelA- and cRel-specific dimers could account for this stimulus specificity. cRel is known to be the key regulator of B cell expansion. We found that the RelA-specific phenotype in LPS-stimulated cells was physiologically relevant: unbiased transcriptome profiling revealed that the inflammatory cytokine IL-6 was hyperactivated in IκBε(-/-) B cells. When IL-6R was blocked, LPS-responsive IκBε(-/-) B cell proliferation was reduced to near wild-type levels. Our results provide novel evidence for a critical role for immune-response functions of IκBε in B cells; it regulates proliferative capacity via at least two mechanisms involving cRel- and RelA-containing NF-κB dimers. This study illustrates the importance of kinetic considerations in understanding the functional specificity of negative-feedback regulators.

The PAI-1 4G/5G polymorphism is not associated with an increased risk of adverse pregnancy outcome in asymptomatic nulliparous women

BACKGROUND

Plasminogen activator inhibitor type 1 (PAI-1) is an important regulator of fibrinolysis. A common deletion polymorphism that results in a sequence of 4G instead of 5G in the promoter region of the gene is associated with a small increase in the risk of venous thromboembolism. Its potential association with adverse pregnancy events remains controversial.

OBJECTIVE

We aimed to assess the impact of the 4G PAI-1 polymorphism on pregnancy outcomes in women who had no prior history of adverse pregnancy outcomes or personal or family history of venous thromboembolism.

PATIENTS/METHODS

This study represents a secondary investigation of a prior prospective cohort study investigating the association between inherited thrombophilias and adverse pregnancy events in Australian women. Healthy nulliparous women were recruited to this study prior to 22 weeks gestation. Genotyping for the 4G/5G PAI-1 gene was performed using Taqman assays in an ABI prism 7700 Sequencer several years after the pregnancy was completed. Pregnancy outcome data were extracted from the medical record. The primary outcome was a composite comprising development of severe pre-eclampsia, fetal growth restriction, major placental abruption, stillbirth or neonatal death.

RESULTS

Pregnancy outcome data were available in 1733 women who were successfully genotyped for this polymorphism. The primary composite outcome was experienced by 139 women (8% of the cohort). Four hundred and fifty-nine women (26.5%) were homozygous for the 4G deletion polymorphism, while 890 (51.4%) were heterozygous. Neither homozygosity nor heterozygosity for the PAI-1 4G polymorphism was associated with the primary composite outcome (homozygous OR = 1.30, 95% CI = 0.81-2.09, P = 0.28, heterozygous OR = 0.84, 95% CI = 0.53-1.31, P = 0.44) or with the individual pregnancy complications.

CONCLUSION

The PAI-1 4G polymorphism is not associated with an increase in the risk of serious adverse pregnancy events in asymptomatic nulliparous women.

Molecular adsorption onto metallic quantum wires

We have studied the adsorption of mercaptopropionic acid, 2,2'-bipyridine, and dopamine onto electrochemically fabricated Cu nanowires. The nanowires are atomically thin with conductance quantized near integer multiples of 2e(2)/h. Upon molecular adsorption, the quantized conductance decreases to a fractional value, due to the scattering of the conduction electrons by the adsorbates. The decrease is as high as 50% for the thinnest nanowires whose conductance is at the lowest quantum step, and smaller for thicker nanowires with conductance at higher quantum steps. The adsorbate-induced conductance changes depend on the binding strengths of the molecules to the nanowires, which are in the order of mercaptopropionic acid, 2,2'-bipyridine, and dopamine, from strongest to weakest. The sensitive dependence of the quantized conductance on molecular adsorption may be used for molecular detection.