Quantitative analysis of direct oral anticoagulant rivaroxaban by terahertz spectroscopy.

Rivaroxaban, as a direct oral anticoagulant, has been widely used in the treatment and prevention of thrombosis disease (TD). However, even if the same dose of rivaroxaban is taken, different pathophysiological characteristics of TD patients determine the differences in plasma concentrations between individuals, leading to the difficulties of dosage selection and plasma concentration control. Conventional rivaroxaban detection methods, including prothrombin time method, anti-Xa assay and liquid chromatography-tandem mass spectrometry (LC-MS/MS), are not widely used in clinical practice due to the limitations of accuracy, speed and cost. Here, we present a simple quantitative detection method for rivaroxaban by terahertz (THz) spectroscopy. Combining density functional theory (DFT) method and THz spectroscopy, the THz absorption peaks of rivaroxaban and the corresponding low-frequency vibrational modes are studied theoretically and experimentally. We find linear relationships between the amplitudes of these characteristic peaks and the concentrations of rivaroxaban. Based on these linear functions, we can analyse the rivaroxaban concentration with a detection time of 1 minute per test and the lowest detection limit of 2 µmol mL-1. As compared to Raman spectroscopy method (its detection limit is about 80 µmol mL-1), our method has more potential and is practical for the clinical quantitative detection of rivaroxaban as well as other direct oral anticoagulants.

Diagnosis of methylglyoxal in blood by using far-infrared spectroscopy and o-phenylenediamine derivation.

Methyglyoxal (MGO) is an important pathological factor for diabetic cardiovascular complications. Conventional methods for MGO detection in biological samples, such as high performance liquid chromatography (HPLC)-UV spectrometry, LC-fluorescence spectrometry, and HPLC-mass spectrometry, are time-consuming, high-cost, and complicated. Here, we present a method for MGO quantitative detection based on far-IR spectral analyses. Our method uses o-phenylenediamine (OPD) to produce a chemical reaction with MGO, which results in multiple fingerprint feature changes associated with the molar ratio of MGO and OPD. We use the linear relationship between MGO concentration and peak intensity of the reaction product to quantitatively determine MGO concentration. The corresponding linear detectable range is 5∼2500 nmol/mL nmol per mL with a correlation coefficient of 0.999. This quantitative method is also tested by blood samples with adjusted MGO concentrations, and shows 95% accuracy with only 30s testing time. Our method provides a fast, simple and economical approach to determining MGO concentration in blood.

[Clinical diagnosis of 26 cases of brain death].

OBJECTIVE: To explore clinical diagnostic criterion of brain death. METHODS: Evaluation was made on 26 cases of brain death through routine check-up such as brain stem reflex, GCS, pupil dilatation and limbs reflex. Among whom apnea test was made in 10 cases and EEG-Holter monitoring in 5 cases. Different dose of 1 mg, 2 mg, 5 mg Atropine test in 21 cases of brain death were administered to compare with the result in another 15 cases of deep coma patients. RESULTS: The positive of apnea test has some relation with the mode of respirator executed. The negative of Atropine test in brain death group has significant difference with that of deep coma group (P < 0.05). EEG-Holter is valuable in determining the exact time of brain death. Pupil changes including mydriasis 14 cases, miosis 2 cases and inequality of pupil 5 cases. Limbs reflex was preserved in 5 cases. CONCLUSIONS: A protocol for executing apnea is recommended. Atropine 1 mg should be the first dosage when executing Atropine test. Dynamic EEG has forensic value while mydriasis and loss of limbs reflex should not be regarded as characteristic sign of brain death.