Oral anticoagulants and cognitive impairment in patients with atrial fibrillation: A systematic review with meta-analysis and trial sequential analysis.

BACKGROUND: This systematic review assesses the likelihood of developing dementia and cognitive impairment in patients with atrial fibrillation (AF) receiving non-vitamin K antagonist oral anticoagulants (NOACs) as opposed to vitamin K antagonists (VKAs). METHODS: We performed a systematic review with meta-analysis and trial sequential analysis (TSA), which encompassed both randomized controlled trials (RCTs) and observational studies. The objective was to assess the impact of NOACs and VKAs on the incidence of dementia in individuals diagnosed with AF. RESULTS: Out of 1914 studies that were screened, 31 studies were included in the final analysis, which consisted of nine RCTs or their subsequent post-hoc analyses, in addition to 22 observational studies. The meta-analysis shows that NOACs were associated with a decreased probability of developing dementia of any cause [Rate Ratio (RR): 0.88; 95 % confidence interval (95 % CI): 0.82-0.94], especially in patients below the age of 75 (RR: 0.78; 95 % CI: 0.73-0.84). Consistent patterns were observed across all forms of dementia and cognitive function decline. The overall evidence indicates notable variability in the outcome with a moderate-to-low degree of certainty. The TSA suggests that the total sample size of the included trials (155,647 patients) was significantly smaller than the required information size of 784,692 patients to discern the true effect of NOAC versus VKA in terms of reducing dementia risk. CONCLUSION: NOACs may reduce the likelihood of developing dementia in patients with AF, particularly in those under the age of 75. This review highlights the urgent necessity for thorough research to determine the efficacy of NOACs in safeguarding cognitive health.

Fatty acid-binding protein-3 and renal function decline in patients with chronic coronary syndrome.

BACKGROUND: Renal dysfunction is common in patients with coronary artery disease. Due to the shared vascular pathogenesis between the two conditions, novel biomarkers such as the fatty acid-binding protein-3 (FABP-3) have been proposed for diagnosis and prognosis prediction. This multicentre prospective cohort study investigates the association between FABP-3 and renal dysfunction. HYPOTHESIS: We hypothesized that higher FABP-3 levels are correlated to worse renal outcome. METHODS: Patients with chronic coronary syndrome were classified into three groups based on the initial serum FABP-3 levels. The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation was used to estimate the patient's renal function. Renal events were defined as >25% and >50% decline in estimated glomerular filtration rate (eGFR). Cox multivariable regression was employed to delineate the correlation between FABP-3 and renal dysfunction. RESULTS: A total of 1606 subjects were included. During a mean follow-up of 35.9 months, there were 239 patients with eGFR >25% reduction and 60 patients with >50% reduction. In the Kaplan-Meier survival curve and log-rank test, increased levels of FABP-3 were significantly correlated with eGFR >25% reduction (p < .001) and >50% reduction (p < .001). Multivariate Cox regression model revealed that subjects with higher FABP-3 exhibited a greater risk of eGFR >25% reduction (Group 2: hazard ratio [HR] = 2.328, 95% confidence interval [CI] = 1.521-3.562, p < .001; Group 3: HR = 3.054, 95% CI = 1.952-4.776, p < .001) and >50% reduction (Group 3: HR = 4.838, 95% CI = 1.722-13.591, p = .003). CONCLUSIONS: Serum FABP-3 may serve as a novel biomarker to predict eGFR decline in patients with chronic coronary syndrome.

Optimal stroke preventive strategy for patients aged 80 years or older with atrial fibrillation: a systematic review with traditional and network meta-analysis.

BACKGROUND: An optimal antithrombotic strategy for patients aged 80 years or older with atrial fibrillation (AF) remains elusive. OBJECTIVE: Using a systematic review with traditional and network meta-analysis, we investigated outcomes in AF patients ≥80 years treated with different antithrombotic strategies. METHODS: We searched eligible randomised controlled trials (RCTs) and observational studies from MEDLINE, EMBASE, Cochrane Library and Web of Science databases from inception to 16 December 2021. Research comparing treatment outcomes of novel oral anticoagulants (NOACs), aspirin, vitamin K antagonists (VKAs) or no oral anticoagulant/placebo therapy in patients ≥80 years with AF were included. Outcomes were stroke or systemic embolism (SSE), major bleeding, all-cause mortality, intracranial bleeding (ICH) and gastrointestinal bleeding. Traditional and network meta-analyses were performed. Net clinical benefit integrating SSE and major bleeding was calculated. RESULTS: Fifty-three studies were identified for analysis. In the meta-analysis of RCTs, risk of SSE (risk ratio [RR]: 0.82; 95% confidence interval [CI]: 0.73-0.99) and ICH (RR: 0.38; 95% CI: 0.28-0.52) was significantly reduced when NOACs were compared with VKAs. Network meta-analysis of RCTs demonstrated that edoxaban (P-score: 0.8976) and apixaban (P-score: 0.8528) outperformed other antithrombotic therapies by showing a lower major bleeding risk and better net clinical benefit. Both traditional and network meta-analyses from RCTs combining with observational studies showed consistent results. CONCLUSIONS: In patients aged 80 years or older with AF, NOACs have better outcomes than VKAs regarding efficacy and safety profiles. Edoxaban and apixaban may be preferred treatment options since they are safer than other antithrombotic strategies.

Pharmacological Responses of the G542X-CFTR to CFTR Modulators.

Cystic fibrosis (CF) is a lethal hereditary disease caused by loss-of-function mutations of the chloride channel cystic fibrosis transmembrane conductance regulator (CFTR). With the development of small-molecule CFTR modulators, including correctors that facilitate protein folding and expression and potentiators that promote channel activity, about 90% of the CF patients are now receiving efficacious target therapies. G542X-CFTR, a premature termination codon (PTC) mutation, is the most common disease-associated mutation found in the remaining 10% of patients that await effective drugs to rectify the fundamental defects caused by PTC. In this study, we employed biophysical and biochemical techniques to characterize the pharmacological responses of the translational products of G542X-CFTR to a range of new CFTR modulators. Specifically, we identified two different proteins translated from the G542X-CFTR cDNA using western blotting: the C-terminus truncated protein that responds to the C1 corrector which binds to the N-terminal part of the protein and a full-length CFTR protein through the read-through process. Electrophysiological data suggest that the read-through protein, but not the C-terminus truncated one, is functional and responds well to CFTR potentiators despite a lower open probability compared to wild-type CFTR. As the expression of the read-through products can be increased synergistically with the read-through reagent G418 and C1 corrector, but not with combinations of different types of correctors, we concluded that an efficacious read-through reagent is a prerequisite for mitigating the deficits of G542X-CFTR. Moreover, the CFTR potentiators may help improve the effectiveness of future combinational therapy for patients carrying PTCs such as G542X.

Faculty appointment and promotion in Taiwan's medical schools, a systematic analysis.

BACKGROUND: A rigorous faculty appointment and promotion (FAP) system is vital for the success of any academic institution. However, studies examining the FAP system in Asian universities are lacking. We surveyed the FAP policies of Taiwan's medical schools and identified an overreliance on the CJA score (manuscript Category, Journal quality, and Author order). The potential shortcomings of this metric and recommendations for refinement were discussed. METHODS: We obtained the FAP documents from all 12 medical schools in Taiwan, and analyzed their use of traditional versus non-traditional criteria for FAP according to a published methodology. The influence of the journal impact factor (JIF) on the FAP process was quantified by comparing its relative weight between papers with two extreme JIFs. To better understand the research impact and international standing of each school, we utilized the public bibliographic database to rank universities by the number of papers, and the proportions of papers within the top 10% or 50% citation. RESULTS: Compared with other countries, Taiwan's medical schools focus more on the quantifiable quality of the research, mostly using a "CJA" score that integrates the category, JIF or ranking, and authorship of a paper, with the JIF being the most influential factor. The CJA score for an article with a JIF of 20 can be up to three times the threshold for promotion to Assistant Professor. The emphasis on JIF is based on a presumed correlation between JIF and citation counts. However, our analysis shows that Taiwan's medical schools have lower-than-average citation counts despite a competitive rank in the number of publications. CONCLUSIONS: The JIF plays an unrivaled role in determining the outcome of FAP in Taiwan's medical schools, mostly via the CJA system. The questionable effectiveness of the current system in elevating the international standing of Taiwan's higher-education institutions calls for a re-examination of the FAP system. We recommend a reduction in the relative importance of CJA score in the FAP system, adopting more rigorous metrics such as the h-index for evaluating research quality, and supporting more research aimed at improving the FAP system.

Generation of human induced pluripotent stem cells from cystic fibrosis patient carrying nonsense mutation (p.S308X) in CFTR gene.

Cystic fibrosis (CF) is a genetic disease affects CFTR channel synthesis. While 90 percent of the CF patients now benefit from small molecule target therapies, this treatment has yet to extend to those bearing nonsense mutations. Studies of these rare mutations using cell lines with native pathological signatures of the disease may lead to breakthroughs in therapeutic development. Here, we report the generation of CF patient-derived induced pluripotent stem cells (iPSCs) carrying a nonsense mutation at position 308 (S308X). The pluripotency and genomic profile of the iPSC line was validated as a resource that can enable future research for CF.

Blood pressure variability and cognitive dysfunction: A systematic review and meta-analysis of longitudinal cohort studies.

The variability of blood pressure (BPV) has been suggested as a clinical indicator for cognitive dysfunction, yet the results from clinical studies are variable. This study investigated the relationship between BPV and the risk of cognitive decline or dementia. Bibliographic databases, including PubMed, Scopus, and Embase, were searched systematically for longitudinal cohort studies with BPV measurements and neuropsychological examinations or dementia diagnosis. A traditional meta-analysis with subgroup analysis, and a further dose-response meta-analysis were conducted. Twenty cohort studies with 7 924 168 persons were included in this review. The results showed that a higher systolic BPV (SBPV), when measured with the coefficient of variation (SBP-CV) or standard deviation (SBP-SD), was associated with a higher risk of all-cause dementia diagnosis but not incidence of cognitive decline on neuropsychological examinations. In subgroup analysis, the effect was more prominent when using BPV of shorter timeframes, during shorter follow-ups, or among the elderly aged more than 65 years. No dose-response relationship could be found. Our study suggested possible positive associations between SBPV and the risk of dementia. Further studies are required to validate these findings.

Organoids as a personalized medicine tool for ultra-rare mutations in cystic fibrosis: The case of S955P and 1717-2A>G.

BACKGROUND: For most of the >2000 CFTR gene variants reported, neither the associated disease liability nor the underlying basic defect are known, and yet these are essential for disease prognosis and CFTR-based therapeutics. Here we aimed to characterize two ultra-rare mutations - 1717-2A > G (c.1585-2A > G) and S955P (p.Ser955Pro) - as case studies for personalized medicine. METHODS: Patient-derived rectal biopsies and intestinal organoids from two individuals with each of these mutations and F508del (p.Phe508del) in the other allele were used to assess CFTR function, response to modulators and RNA splicing pattern. In parallel, we used cellular models to further characterize S955P independently of F508del and to assess its response to CFTR modulators. RESULTS: Results in both rectal biopsies and intestinal organoids from both patients evidence residual CFTR function. Further characterization shows that 1717-2A > G leads to alternative splicing generating <1% normal CFTR mRNA and that S955P affects CFTR gating. Finally, studies in organoids predict that both patients are responders to VX-770 alone and even more to VX-770 combined with VX-809 or VX-661, although to different levels. CONCLUSION: This study demonstrates the high potential of personalized medicine through theranostics to extend the label of approved drugs to patients with rare mutations.

Positional effects of premature termination codons on the biochemical and biophysical properties of CFTR.

KEY POINTS: Biochemical and biophysical characterizations of three nonsense mutations of cystic fibrosis transmembrane conductance regulator (CFTR) associated with a severe form of cystic fibrosis (CF) reveal the importance and heterogenous effects of the position of the premature termination codon (PTC) on the CFTR protein function. Electrophysiological studies of W1282X-CFTR, whose PTC is closer to the C-terminus of CFTR, suggest the presence of both C-terminus truncated CFTR proteins that are poorly functional and read-through, full-length products. For G542X- and E60X-CFTR, the only mechanism capable of generating functional proteins is the read-through, but the outcome of read-through products is highly variable depending on the interplay between the missense mutation caused by the read-through and the structural context of the protein. Pharmacological studies of these three PTCs with various CFTR modulators suggest position-dependent therapeutic strategies for these disease-inflicting mutations. ABSTRACT: About one-third of genetic diseases and cancers are caused by the introduction of premature termination codons (PTCs). In theory, the location of the PTC in a gene determines the alternative mechanisms of translation, including premature cessation or reinitiation of translation, and read-through, resulting in differential effects on protein integrity. In this study, we used CFTR as a model system to investigate the positional effect of the PTC because of its well-understood structure-function relationship and pathophysiology. The characterization of three PTC mutations, E60X-, G542X- and W1282X-CFTR revealed heterogenous effects of these PTCs on CFTR function. The W1282X mutation results in both C-terminus truncated and read-through proteins that are partially or fully functional. In contrast, only the read-through protein is functional with E60X- and G542X-CFTR, although abundant N-terminus truncated proteins due to reinitiation of translation were detected in E60X-CFTR. Single-channel studies of the read-through proteins of E60X- and G542X-CFTR demonstrated that both mutations have a single-channel amplitude similar to wild type (WT), and good responses to high-affinity ATP analogues, suggesting intact ion permeation pathways and nucleotide binding domains (NBDs), albeit with reduced open probability (Po ). The comparison of the Po of these mutations with the proposed missense mutations revealed potential identities of the read-through products. Importantly, a majority of the functional protein studied responds to CFTR modulators like GLPG1837 and Lumacaftor. These results not only expand current understanding of the molecular (patho)physiology of CFTR, but also infer therapeutic strategies for different PTC mutations at large.

Structural mechanisms for defective CFTR gating caused by the Q1412X mutation, a severe Class VI pathogenic mutation in cystic fibrosis.

KEY POINTS: Electrophysiological characterization of Q1412X-CFTR, a C-terminal truncation mutation of cystic fibrosis transmembrane conductance regulator (CFTR) associated with the severe form of cystic fibrosis (CF), reveals a gating defect that has not been reported previously. Mechanistic investigations of the gating deficit in Q1412X-CFTR suggest that the reduced open probability in Q1412X-CFTR is the result of a disruption of the function of the second ATP binding site (or site 2) in the nucleotide binding domains (NBDs). Detailed comparisons of several mutations with different degrees of truncation in the C-terminal region of NBD2 reveal the importance of the last two beta-strands in NBD2 for maintaining proper gating functions. The results of the present study also show that the application of clinically-approved drugs (VX-770 and VX-809) can greatly enhance the function of Q1412X, providing in vitro evidence for a therapeutic strategy employing both reagents for patients bearing Q1412X or similar truncation mutations. ABSTRACT: Cystic fibrosis (CF) is caused by loss-of-function mutations of cystic fibrosis transmembrane conductance regulator (CFTR), a phosphorylation-activated but ATP-gated chloride channel. Based on the molecular mechanism of CF pathogenesis, disease-associated mutations are categorized into six classes. Among them, Class VI, whose members include some of the C-terminal truncation mutations such as Q1412X, is defined as decreased membrane expression because of a faster turnover rate. In the present study, we characterized the functional properties of Q1412X-CFTR, a severe-form premature stop codon mutation. We confirmed previous findings of a ∼90% decrease in membrane expression but found a ∼95% reduction in the open probability (Po ). Detailed kinetic studies support the idea that the gating defect is the result of a dysfunctional ATP-binding site 2 in the nucleotide binding domains (NBDs). Because the Q1412X mutation results in a deletion of the last two beta-strands in NBD2 and the whole C-terminal region, we further characterized truncation mutations with different degrees of deletion in this segment. Mutations that completely or partially remove the C-terminus of CFTR at the same time as keeping an intact NBD2 (i.e. D1425X and S1455X) assume gating function almost identical to that of wild-type channels. However, the deletion of the last beta-strand in the NBD2 (i.e. N1419X) causes gating dysfunction that is milder than that of Q1412X. Thus, normal CFTR gating requires structural integrity of NBD2. Moreover, our observation that clinically-approved VX-809 (Lumacaftor, Vertex Pharmaceuticals, Boston, MA, USA) and VX-770 (Ivacaftor, Vertex Pharmaceuticals, Boston, MA, USA) significantly enhance the overall function of Q1412X-CFTR provides the conceptual basis for the treatment of patients carrying this mutation.

Structural mechanisms of CFTR function and dysfunction.

Cystic fibrosis (CF) transmembrane conductance regulator (CFTR) chloride channel plays a critical role in regulating transepithelial movement of water and electrolyte in exocrine tissues. Malfunction of the channel because of mutations of the cftr gene results in CF, the most prevalent lethal genetic disease among Caucasians. Recently, the publication of atomic structures of CFTR in two distinct conformations provides, for the first time, a clear overview of the protein. However, given the highly dynamic nature of the interactions among CFTR's various domains, better understanding of the functional significance of these structures requires an integration of these new structural insights with previously established biochemical/biophysical studies, which is the goal of this review.

Functional characterization reveals that zebrafish CFTR prefers to occupy closed channel conformations.

Cystic fibrosis transmembrane conductance regulator (CFTR), the culprit behind the genetic disease cystic fibrosis (CF), is a phosphorylation-activated, but ATP-gated anion channel. Studies of human CFTR over the past two decades have provided an in-depth understanding of how CFTR works as an ion channel despite its structural resemblance to ABC transporters. Recently-solved cryo-EM structures of unphosphorylated human and zebrafish CFTR (hCFTR and zCFTR), as well as phosphorylated ATP-bound zebrafish and human CFTR offer an unprecedented opportunity to understand CFTR's function at a molecular level. Interestingly, despite millions of years of phylogenetic distance between human and zebrafish, the structures of zCFTR and hCFTR exhibit remarkable similarities. In the current study, we characterized biophysical and pharmacological properties of zCFTR with the patch-clamp technique, and showed surprisingly very different functional properties between these two orthologs. First, while hCFTR has a single-channel conductance of 8.4 pS with a linear I-V curve, zCFTR shows an inwardly-rectified I-V relationship with a single-channel conductance of ~3.5 pS. Second, single-channel gating behaviors of phosphorylated zCFTR are very different from those of hCFTR, featuring a very low open probability Po (0.03 ± 0.02, vs. ~0.50 for hCFTR) with exceedingly long closed events and brief openings. In addition, unlike hCFTR where each open burst is clearly defined with rare short-lived flickery closures, the open bursts of zCFTR are not easily resolved. Third, although abolishing ATP hydrolysis by replacing the catalytic glutamate with glutamine (i.e., E1372Q) drastically prolongs the open bursts defined by the macroscopic relaxation analysis in zCFTR, the Po within a "locked-open" burst of E1372Q-zCFTR is only ~ 0.35 (vs. Po > 0.94 in E1371Q-hCFTR). Collectively, our data not only provide a reasonable explanation for the unexpected closed-state structure of phosphorylated E1372Q-zCFTR with a canonical ATP-bound dimer of the nucleotide binding domains (NBDs), but also implicate significant structural and functional differences between these two evolutionarily distant orthologs.

Modulation of CFTR gating by permeant ions.

Cystic fibrosis transmembrane conductance regulator (CFTR) is unique among ion channels in that after its phosphorylation by protein kinase A (PKA), its ATP-dependent gating violates microscopic reversibility caused by the intimate involvement of ATP hydrolysis in controlling channel closure. Recent studies suggest a gating model featuring an energetic coupling between opening and closing of the gate in CFTR's transmembrane domains and association and dissociation of its two nucleotide-binding domains (NBDs). We found that permeant ions such as nitrate can increase the open probability (Po) of wild-type (WT) CFTR by increasing the opening rate and decreasing the closing rate. Nearly identical effects were seen with a construct in which activity does not require phosphorylation of the regulatory domain, indicating that nitrate primarily affects ATP-dependent gating steps rather than PKA-dependent phosphorylation. Surprisingly, the effects of nitrate on CFTR gating are remarkably similar to those of VX-770 (N-(2,4-Di-tert-butyl-5-hydroxyphenyl)-4-oxo-1,4-dihydroquinoline-3-carboxamide), a potent CFTR potentiator used in clinics. These include effects on single-channel kinetics of WT CFTR, deceleration of the nonhydrolytic closing rate, and potentiation of the Po of the disease-associated mutant G551D. In addition, both VX-770 and nitrate increased the activity of a CFTR construct lacking NBD2 (ΔNBD2), indicating that these gating effects are independent of NBD dimerization. Nonetheless, whereas VX-770 is equally effective when applied from either side of the membrane, nitrate potentiates gating mainly from the cytoplasmic side, implicating a common mechanism for gating modulation mediated through two separate sites of action.