Procathepsin D cannot autoactivate to cathepsin D at acid pH

AbstractThe amino acid sequence of the propart of bovine procathepsin D was determined at the protein level. Incubation of the isolated procathepsin D at pH 3.5–5.0 for 30–120 min leads to a 2 kDa reduction in its molecular mass, as seen by SDS-PAGE. The activation product is pseudocathepsin D and is the result of a proteolytic cleavage between LeuP26 and IleP27 in the propart. Incubation at pH 5.0 for 20 h of either procathepsin D or pseudocathepsin D results in both cases in approximately equal amounts of pseudocathepsin D and a further processed intermediate, nine amino acids shorter than pseudocathepsin D. No reaction products corresponding to cathepsin D with a mature amino terminus were observed, showing that autoproteolysis alone cannot generate the mature form found in the lysosomes

Temporal Trends in Incidence, Prevalence, and Mortality of Atrial Fibrillation in Primary Care

Background Incidence and prevalence of atrial fibrillation ( AF ) are expected to increase dramatically; however, we currently lack comprehensive data on temporal trends in unselected clinical populations. Methods and Results Analysis of the UK Clinical Practice Research Datalink ( CPRD ) from 1998 to 2010 of patients with incident AF , excluding major valvular disease, linked to hospital admission data and national statistics. Fifty‐seven thousand eight hundred eighteen adults were identified with mean age 74.2 ( SD , 11.7) years and 48.3% women. Overall age‐adjusted incidence of AF per 1000 person years was 1.11 (95% CI , 1.09–1.13) in 1998–2001, 1.33 (1.31–1.34) in 2002–2006, and 1.33 (1.31–1.35) in 2007–2010. Ongoing increases in incidence were noted for patients aged ≥75 years, with similar temporal patterns in women and men. Associated comorbidities varied over time, with a constant prevalence of previous stroke, increases in hypertension and diabetes mellitus, and decreases in ischemic heart disease. Among patients aged 55 to 74 years, there was a significant reduction in mortality over time ( P &lt;0.001), but mortality rates in patients aged ≥75 years remained static at 14% to 15% per year ( P =0.84). Projections of AF prevalence demonstrated a constant yearly rise, increasing from 700 000 patients in 2010 to between 1.3 and 1.8 million patients with AF in the United Kingdom by 2060. Conclusions In a large general practice population, incident AF increased and then plateaued overall, with a continued increase in patients aged ≥75 years. The large projected increase in AF prevalence associated with temporal changes in AF ‐related comorbidities suggests the need for comprehensive implementation of AF prevention and management strategies. </jats:sec

Thromboembolic Risk in Patients With Pneumonia and New-Onset Atrial Fibrillation Not Receiving Anticoagulation Therapy

IMPORTANCE: New-onset atrial fibrillation (AF) is commonly reported in patients with severe infections. However, the absolute risk of thromboembolic events without anticoagulation remains unknown. OBJECTIVE: To investigate the thromboembolic risks associated with AF in patients with pneumonia, assess the risk of recurrent AF, and examine the association of initiation of anticoagulation therapy with new-onset AF. DESIGN, SETTING, AND PARTICIPANTS: This population-based cohort study used linked Danish nationwide registries. Participants included patients hospitalized with incident community-acquired pneumonia in Denmark from 1998 to 2018. Statistical analysis was performed from August 15, 2021, to March 12, 2022. EXPOSURES: New-onset AF. MAIN OUTCOMES AND MEASURES: Thromboembolic events, recurrent AF, and all-cause death. Estimated risks were calculated for thromboembolism without anticoagulation therapy, new hospital or outpatient clinic contact with AF, initiation of anticoagulation therapy, and all-cause death at 1 and 3 years of follow-up. Death was treated as a competing risk, and inverse probability of censoring weights was used to account for patient censoring if they initiated anticoagulation therapy conditioned on AF. RESULTS: Among 274 196 patients hospitalized for community-acquired pneumonia, 6553 patients (mean age [SD], 79.1 [11.0] years; 3405 women [52.0%]) developed new-onset AF. The 1-year risk of thromboembolism was 0.8% (95% CI, 0.8%-0.8%) in patients without AF vs 2.1% (95% CI, 1.8%-2.5%) in patients with new-onset AF without anticoagulation; this risk was 1.4% (95% CI, 1.0%-2.0%) among patients with AF with intermediate stroke risk and 2.8% (95% CI, 2.3%-3.4%) in patients with AF with high stroke risk. Three-year risks were 3.5% (95% CI, 2.8%-4.3%) among patients with intermediate stroke risk and 5.3% (95% CI, 4.4%-6.5%) among patients with high stroke risk. Among patients with new-onset AF, 32.9% (95% CI, 31.8%-34.1%) had a new hospital contact with AF, and 14.0% (95% CI, 13.2%-14.9%) initiated anticoagulation therapy during the 3 years after incident AF diagnosis. At 3 years, the all-cause mortality rate was 25.7% (95% CI, 25.6%-25.9%) in patients with pneumonia without AF vs 49.8% (95% CI, 48.6%-51.1%) in patients with new-onset AF. CONCLUSIONS AND RELEVANCE: This cohort study found that new-onset AF after community-acquired pneumonia was associated with an increased risk of thromboembolism, which may warrant anticoagulation therapy. Approximately one-third of patients had a new hospital or outpatient clinic contact for AF during the 3-year follow-up, suggesting that AF triggered by acute infections is not a transient, self-terminating condition that reverses with resolution of the infection

Antiplatelet Therapy in Patients With Abdominal Aortic Aneurysm Without Symptomatic Atherosclerotic Disease

IMPORTANCE: Patients with abdominal aortic aneurysm have a high risk of ischemic events associated with concomitant atherosclerotic cardiovascular disease, and current clinical practice guidelines recommend antiplatelet therapy to mitigate this risk. However, in patients with aneurysms without symptomatic atherosclerosis, the benefit of antiplatelet therapy has been sparsely investigated.OBJECTIVE: To estimate the effect of antiplatelets on the risk of ischemic events and bleeding in individuals with abdominal aneurysms with no symptomatic atherosclerotic vascular disease.DESIGN, SETTING, AND PARTICIPANTS: A comparative effectiveness research study using a target trial emulation framework was performed. Population-based, cross-linked observational data from Danish national health registries containing comprehensive, individual-level information on all Danish citizens were used to evaluate patients who were antiplatelet-naive and diagnosed with abdominal aortic aneurysms, with no record of symptomatic atherosclerotic vascular disease, from January 1, 2010, through August 21, 2021.EXPOSURE: Prescription filled for aspirin or clopidogrel.MAIN OUTCOMES AND MEASURES: Risk of ischemic events (myocardial infarction and/or ischemic stroke) and risk of major bleeding. For target trial emulation, trials were emulated as sequential, contingent on patient eligibility at the time of inclusion, and were evaluated by means of pooled logistic regression models to estimate the intention-to-treat and as-treated effects, expressed as hazard ratio (HR) and event-free survival.RESULTS: A total of 6344 patients (65.2% men; age, 72 [IQR, 64-78] years) provided 131 047 trial cases; 3363 of these cases involved initiation of antiplatelet therapy and 127 684 did not. A total of 182 ischemic events occurred among initiators and 5602 ischemic events occurred among noninitiators, corresponding to an intention-to-treat HR of 0.91 (95% CI, 0.73-1.17) and an estimated absolute event-free survival difference of -0.6% (95% CI, -1.7% to 0.5%). After censoring nonadherent person-time, the treatment HR was 0.90 (95% CI, 0.68-1.20), with similar risk difference. For bleeding, the intention-to-treat HR was 1.26 (95% CI, 0.97-1.58) and the event-free survival difference was 1.0%. The treatment HR was 1.21 (95% CI, 0.82-1.72); the risk difference was similar.CONCLUSIONS AND RELEVANCE: In this study, no evidence of effectiveness of antiplatelet therapy to lower the risk of ischemic events and a trend toward higher bleeding risk was noted. The observed differences between the treatment groups were minimal, suggesting limited clinical relevance of antiplatelet treatment.</p