Designing and developing small organic molecules for use as urease inhibitors is challenging due to the need for ecosystem sustainability and the requirement to prevent health risks related to the human stomach and urinary tract. Moreover, imaging analysis is widely utilized for tracking infections in intracellular and in vivo systems, which requires drug molecules with emissive potential, specifically in the low-energy region. This study comprises the synthesis of a Schiff base ligand and its selected transition metals to evaluate their UV/fluorescence properties, inhibitory activity against urease, and molecular docking. Screening of the symmetrical cage-like ligand and its metal complexes with various eco-friendly transition metals revealed significant urease inhibition potential. The IC₅₀ value of the ligand for urease inhibition was 21.80 ± 1.88 µM, comparable to that of thiourea. Notably, upon coordination with transition metals, the ligand–nickel and ligand–copper complexes exhibited even greater potency than the reference compound, with IC₅₀ values of 11.8 ± 1.14 and 9.31 ± 1.31 µM, respectively. The ligand–cobalt complex exhibited an enzyme inhibitory potential comparable with thiourea, while the zinc and iron complexes demonstrated the least activity, which might be due to weaker interactions with the investigated protein. Meanwhile, all the metal complexes demonstrated a pronounced optical response, which could be utilized for fluorescence-guided targeted drug delivery applications in the future. Molecular docking analysis and IC₅₀ values from in vitro urease inhibition screening showed a trend of increasing activity from compounds 7d to 7c to 7b. Enzyme kinetics studies using the Lineweaver–Burk plot indicated mixed-type inhibition against 7c and non-competitive inhibition against 7d.

Purpose: Although repeat CT pulmonary angiography (CTPA) after a negative index examination in the emergency department (ED) is common, its diagnostic utility remains uncertain. This study aimed to determine the incidence and diagnostic yield of repeat CTPA after a negative index examination in the ED. Methods: This retrospective cohort study included adults undergoing CTPA across three EDs at our center from 2016 to 2017. CTPA results were classified as positive, negative, or other (equivocal or negative with reported limitations) based on radiology reports. Patients with a negative index CTPA were followed for two years to identify repeat examinations. Diagnostic yield of repeat CTPA at 1 month, 1 year, and 2 years was compared with that of the index examination using a likelihood ratio test for nested proportions. Results: Among 3,112 patients (median age, 60.1 years; 59.1% women), 331 (10.6%) had a positive index CTPA. Of 2,412 patients with a negative index examination, 297 (12.3%) underwent repeat CTPA within 2 years, including 202 (8.4%) performed in our ED. The diagnostic yield of repeat CTPA performed in our ED was lower than that of the index examination: 3.8% (1/26; p = 0.20) at 1 month, 6.0% (9/150; p = 0.051) at 1 year, and 6.4% (13/202; p = 0.04) at 2 years. Conclusion: Repeat CTPA after a negative examination demonstrated a lower diagnostic yield than initial imaging, highlighting an opportunity for more selective use of repeat CTPA guided by clinical pretest probability.