Atrial Fibrillation and Shock: Unmasking Theophylline Toxicity

Could the serum glucose/potassium ratio offer an early reliable predictor of life-threatening events in acute methylxanthine intoxication?

Methylxanthines are widely used to manage pulmonary disorders, particularly in developing countries. Methylxanthines are unsafe due to their narrow therapeutic index and associated morbidity and mortality. The current study aimed to investigate the role of glucose/potassium ratio as a substantially useful early predictor of life-threatening events (LTEs) in the form of cardiovascular and neurological complications among methylxanthine users. A retrospective cohort study was conducted using medical records of patients diagnosed with acute methylxanthine intoxications and presented to an Egyptian Poison Control Center for 2 years. A total of 366 patients were enrolled. Of them, 59 patients (16.1%) were complicated with LTEs. The most frequent serious arrhythmia was T wave inversion (45.6% of patients with LTEs). Laboratory investigations that could significantly predict LTEs were the random blood glucose and potassium levels, glucose/potassium ratio, pH, liver transaminases, HCO3 level, hemoglobin, and platelet count (P < 0.05). The glucose/potassium ratio was the best predictor of LTEs (odds ratio = 2.92, and 95% confidence interval = 2.02-4.23). With an excellent area under the curve (0.906) and at a cutoff of 2.44, that ratio could correctly classify the patients based on their risk of LTEs with an overall accuracy of 73% (sensitivity of 88% and specificity of 70%). The current study endorsed an important, feasible, and easily obtainable ratio that could predictor stratify the patients according to severity and risk of LTEs, which guides the decision-making and prioritizes the treatment lines in methylxanthine intoxicated patients.

A Disposable Sensor Chip Using a Paste Electrode with Surface-Imprinted Graphite Particles for Rapid and Reagentless Monitoring of Theophylline

This work focuses on a carbon-based imprinted polymer composite, employed as a molecular recognition and sensing interface in fabricating a disposable electrochemical sensor. The carbon-paste electrode was made of a molecularly imprinted polymer comprising a copolymer of methacrylic acid as the functional monomer and blended crosslinking monomers of N,N'-methylenebisacrylamide, and ethylene glycol dimethacrylate, with theophylline as the template. The analytical properties of the proposed theophylline sensor were investigated, and the findings revealed an increase in differential pulse voltammetric current compared to the non-imprinted electrode. Under optimized conditions, the sensor has shown high sensitivity, high selectivity, lower detection limit (2.5 µg/mL), and satisfactory long-term stability. Further, the sensor was tested in whole bovine blood and validated without any matrix effect and cross-reactivity. Additionally, chronoamperometry of the sensor chip supported a rapid determination of THO with a short response time of 3 s. This carbon-paste electrode is highly specific for theophylline and may be applied as a drug sensor for clinical use.

Recent Progress on Single-Molecule Detection Technologies for Food Safety

Rapid and sensitive detection technologies for food contaminants play vital roles in food safety. Due to the complexity of the food matrix and the trace amount distribution, traditional methods often suffer from unsatisfying accuracy, sensitivity, or specificity. In past decades, single-molecule detection (SMD) has emerged as a way to realize the rapid and ultrasensitive measurement with low sample consumption, showing a great potential in food contaminants detection. For instance, based on the nanopore technique, simple and effective methods for single-molecule analysis of food contaminants have been developed. To our knowledge, there has been a rare review that focuses on SMD techniques for food safety. The present review attempts to cover some typical SMD methods in food safety, including electrochemistry, optical spectrum, and atom force microscopy. Then, recent applications of these techniques for detecting food contaminants such as biotoxins, pesticides, heavy metals, and illegal additives are reviewed. Finally, existing research challenges and future trends of SMD in food safety are also tentatively proposed.

A split aptamer sensing platform for highly sensitive detection of theophylline based on dual-color fluorescence colocalization and single molecule photobleaching

A new split aptamer sensing platform is developed for highly sensitive and selective detection of theophylline based on single molecule photobleaching (SMPB) technique. The sensing system contains two probes. One is formed by one streptavidin and four biotinylated RNA fragments labelled with fluorescein isothiocyanate (FITC). Each biotinylated RNA fragment contains two repeating aptamer fragments. The other probe is the complementary aptamer fragment labelled with Cy5 dye. The existence of theophylline can trigger the first probe to bind as many as eight Cy5-labelled probes. The average combined number depends on the theophylline concentration and can be measured by SMPB technique. In the sensing system, the dual-color fluorescence colocalization is performed by the red fluorophore (Cy5) and green fluorophore (FITC), in which the red fluorophore is utilized for quantitative counting of photobleaching steps, while the green fluorophore serves as a counting reference to increase detection efficiency. On basis of the principle, an ultra-sensitive sensing platform of theophylline is created with a low limit of detection (LOD) of 0.092 nM. This work provides not only a highly sensitive method for theophylline detection but also a novel perspective for the applications of SMPB technology to construct biosensors.