Dialysis nurses' knowledge, attitude, practices, and self-efficacy regarding vascular access care: A multicenter cross-sectional survey in Singapore.

BACKGROUND: Dialysis nurses play a pivotal role in the management of vascular access (VA), physician-patient liaison, and patient education for hemodialysis patients. This multicenter study aims to review the dialysis nurses' knowledge, attitude, practice, and self-efficacy toward providing care for patients' VA. METHODS: A multi-centered study was conducted using a self-administered survey. Nurses from 47 Singapore dialysis centers (five hospital-based and 42 community-based) providing hemodialysis were invited to participate on a voluntary and anonymous basis from April to November 2022. The survey consists of nurses' knowledge on VA (10 items), attitude on VA care (six items), usual practices (seven items), and self-efficacy in VA cannulation and management (six items). The total scores for the knowledge, attitude, and self-efficacy components were 50, 30, and 30 respectively. The instrument has been validated in a pilot study. RESULTS: In total, five hundred sixteen dialysis nurses participated the survey. The mean (±SD) knowledge score of the participants toward VA care was 30.0 (±8.1) over a total score of 50. The means (±SD) of their attitude and self-efficacy scores were 24.4 (±4.1) and 24.2 (±3.1) over 30 respectively. The majority of the nurses (84.1% in hospital-based centers and 98.9% in community-based centers) conducted patient education in some aspects of VA care. The percentage of nurses indicated need for referral to access specialists due to various abnormalities varied significantly between the hospital-based and community-based settings. In the multivariable linear regression analysis, longer working experience was a significant factor for higher knowledge score (B = 0.26; p = 0.001), attitude score (B = 0.08; p = 0.01), and self-efficacy score (B = 0.34; p < 0.001). CONCLUSION: Dialysis nurses in Singapore have satisfactory knowledge, practice, and self-efficacy on VA care. The majority of them expressed positive opinions toward the VA-related training they received, new technologies, and communications. The identified knowledge and practice gaps could be incorporated into the future training programs.

Tixagevimab and Cilgavimab Administration for Hemodialysis Patients at Community-Based Dialysis Centers in Singapore as Pre-Exposure Prophylaxis for SARS-CoV-2 Infection.

INTRODUCTION:  Hemodialysis patients are deemed to be immunosuppressed and may not be able to mount an adequate response to vaccination against the SARS-CoV-2 virus. Due to the higher morbidity and mortality in this vulnerable group, pre-exposure prophylaxis with monoclonal antibodies was introduced as an additional measure for protection in selected community-based hemodialysis patients in Singapore. Tixagevimab and cilgavimab, available as Evusheld, were used for this purpose. METHODS:  A government-sponsored clinical administration program with the provision of 200 doses of Evusheld at no cost to the patients was implemented. Patient selection criteria to further risk-stratify this vulnerable hemodialysis patient cohort was developed and 200 patients were finally selected. Evusheld administration was done over a period of two months, as two consecutive injections were given at two separate intramuscular sites, which constituted one administration. Data were collected as part of a retrospective clinical audit, as part of a routine quality monitoring process for this patient care program. Real-world evidence was generated to assess the impact on mortality, hospitalization rate, reason for hospitalization, and any associated morbidity. RESULTS:  No adverse events from the Evusheld administration were noted. All recipients had received COVID-19 vaccinations prior to Tixa-Cilga, with a range of one to five doses. A total of 198 (99%) completed two doses and 189 (95%) completed three doses, out of which, 14 (7%) patients contracted COVID-19 infection over three months. The overall hospitalization rate was 2% (four out of 200 patients). Severe illness that required intensive care unit stay was therefore seen in only 2 (1%) out of 200 patients. None of the infected patients died. DISCUSSION:  A significant reduction in severity of illness, hospitalization rate, and mortality was found with pre-exposure prophylaxis with tixagevimab and cilgavimab, in this real-world experience from Singapore. Evusheld administration reduced the hospitalization rate from 42.5% to 2%, which is a reduction of 95.3% (p<0.0001). Symptoms in infected patients were mild, with only 1% being admitted to the intensive care unit. The mortality rate from COVID-19 infection was reduced from 2.5% to 0% with Evusheld.  Conclusion: Mass administration of prophylactic treatments for vulnerable populations can be challenging in community-based settings and the successful implementation of such a program has been described. The findings can have health policy implications for the protection of such immunocompromised patients in the future. The combination of tixagevimab and cilgavimab, available as Evusheld in Singapore, was safe to use in hemodialysis patients, with no adverse events noted. There was a significant reduction in hospitalization rates and intensive care unit admissions with a zero-mortality rate due to COVID-19 infection, after pre-exposure prophylaxis.

The kinase DYRK1A reciprocally regulates the differentiation of Th17 and regulatory T cells.

The balance between Th17 and T regulatory (Treg) cells critically modulates immune homeostasis, with an inadequate Treg response contributing to inflammatory disease. Using an unbiased chemical biology approach, we identified a novel role for the dual specificity tyrosine-phosphorylation-regulated kinase DYRK1A in regulating this balance. Inhibition of DYRK1A enhances Treg differentiation and impairs Th17 differentiation without affecting known pathways of Treg/Th17 differentiation. Thus, DYRK1A represents a novel mechanistic node at the branch point between commitment to either Treg or Th17 lineages. Importantly, both Treg cells generated using the DYRK1A inhibitor harmine and direct administration of harmine itself potently attenuate inflammation in multiple experimental models of systemic autoimmunity and mucosal inflammation. Our results identify DYRK1A as a physiologically relevant regulator of Treg cell differentiation and suggest a broader role for other DYRK family members in immune homeostasis. These results are discussed in the context of human diseases associated with dysregulated DYRK activity.

Applying the logic of genetic interaction to discover small molecules that functionally interact with human disease alleles.

Despite rapid advances in the genetics of complex human diseases, understanding the significance of human disease alleles remains a critical roadblock to clinical translation. Here, we present a chemical biology approach that uses perturbation with small molecules of known mechanism to reveal mechanistic and therapeutic consequences of human disease alleles. To maximize human applicability, we perform chemical screening on multiple cell lines isolated from individual patients, allowing the effects of disease alleles to be studied in their native genetic context. Chemical screen analysis combines the logic of traditional genetic interaction screens with analytic methods from high-dimensionality gene expression analyses. We rank compounds according to their ability to discriminate between cell lines that are mutant versus wild type at a disease gene (i.e., the compounds induce phenotypes that differ the most across the two classes). A technique called compound set enrichment analysis (CSEA), modeled after a widely used method to identify pathways from gene expression data, identifies sets of functionally or structurally related compounds that are statistically enriched among the most discriminating compounds. This chemical:genetic interaction approach was applied to patient-derived cells in a monogenic form of diabetes and identified several classes of compounds (including FDA-approved drugs) that show functional interactions with the causative disease gene, and also modulate insulin secretion, a critical disease phenotype. In summary, perturbation of patient-derived cells with small molecules of known mechanism, together with compound-set-based pathway analysis, can identify small molecules and pathways that functionally interact with disease alleles, and that can modulate disease networks for therapeutic effect.

Selective modulation of autophagy, innate immunity, and adaptive immunity by small molecules.

Autophagy is an evolutionarily conserved catabolic process that directs cytoplasmic proteins, organelles and microbes to lysosomes for degradation. Autophagy acts at the intersection of pathways involved in cellular stress, host defense, and modulation of inflammatory and immune responses; however, the details of how the autophagy network intersects with these processes remain largely undefined. Given the role of autophagy in several human diseases, it is important to determine the extent to which modulators of autophagy also modify inflammatory or immune pathways and whether it is possible to modulate a subset of these pathways selectively. Here, we identify small-molecule inducers of basal autophagy (including several FDA-approved drugs) and characterize their effects on IL-1ß production, autophagic engulfment and killing of intracellular bacteria, and development of Treg, TH17, and TH1 subsets from naïve T cells. Autophagy inducers with distinct, selective activity profiles were identified that reveal the functional architecture of connections between autophagy, and innate and adaptive immunity. In macrophages from mice bearing a conditional deletion of the essential autophagy gene Atg16L1, the small molecules inhibit IL-1ß production to varying degrees suggesting that individual compounds may possess both autophagy-dependent and autophagy-independent activity on immune pathways. The small molecule autophagy inducers constitute useful probes to test the contributions of autophagy-related pathways in diseases marked by impaired autophagy or elevated IL-1ß and to test novel therapeutic hypotheses.

Systematic characterization of the specificity of the SH2 domains of cytoplasmic tyrosine kinases.

Cytoplasmic tyrosine kinases (CTK) generally contain a Src-homology 2 (SH2) domain, whose role in the CTK family is not fully understood. Here we report the determination of the specificity of 25 CTK SH2 domains by screening one-bead-one-compound (OBOC) peptide libraries. Based on the peptide sequences selected by the SH2 domains, we built Support Vector Machine (SVM) models for the prediction of binding ligands for the SH2 domains. These models yielded support for the progressive phosphorylation model for CTKs in which the overlapping specificity of the CTK SH2 and kinase domains has been proposed to facilitate targeting of the CTK substrates with at least two potential phosphotyrosine (pTyr) sites. We curated 93 CTK substrates with at least two pTyr sites catalyzed by the same CTK, and showed that 71% of these substrates had at least two pTyr sites predicted to bind a common CTK SH2 domain. More importantly, we found 34 instances where there was at least one pTyr site predicted to be recognized by the SH2 domain of the same CTK, suggesting that the SH2 and kinase domains of the CTKs may cooperate to achieve progressive phosphorylation of a protein substrate. This article is part of a Special Issue entitled: From protein structures to clinical applications.

On-bead screening of combinatorial libraries: reduction of nonspecific binding by decreasing surface ligand density.

On-bead screening of one-bead-one-compound (OBOC) libraries provides a powerful method for the rapid identification of active compounds against molecular or cellular targets. However, on-bead screening is susceptible to interference from nonspecific binding, which results in biased screening data and false positives. In this work, we have found that a major source of nonspecific binding is derived from the high ligand loading on the library beads, which permits a macromolecular target (e.g., a protein) to simultaneously interact with multiple ligands on the bead surface. To circumvent this problem, we have synthesized a phosphotyrosyl (pY)-containing peptide library on spatially segregated TentaGel microbeads, which feature a 10-fold reduced peptide loading on the bead surface but a normal peptide loading in the bead interior. The library was screened against a panel of 10 Src homology 2 (SH2) domains including those of Csk and Fyn kinases and adaptor protein SLAP, and the specific recognition motif(s) was successfully identified for each of the domains. In contrast, when the SH2 domains were screened against a control library that contained unaltered (high) ligand loading at the bead surface, six of them exhibited varying degrees of sequence biases, ranging from minor perturbation in the relative abundance of different sequences to the exclusive selection of false positive sequences that have no measurable affinity to the target protein. These results indicate that reduction of the ligand loading on the bead surface represents a simple, effective strategy to largely eliminate the interference from nonspecific binding, while preserving sufficient amounts of materials in the bead interior for compound identification. This finding should further expand the utility of OBOC libraries in biomedical research.