Preparation of poly (methacrylic acid)/graphene oxide aerogel as solid-phase extraction adsorbent for extraction and determination of dopamine and tyrosine in urine of patients with depression.

Dopamine (DA) and l-tyrosine (l-Tyr) are neurotransmitters involved in various neuropsychiatric disorders. Therefore, it is important to monitor their levels for diagnosis and treatment. In this study, we synthesized poly (methacrylic acid)/graphene oxide aerogels (p(MAA)/GOA) by in situ polymerization and freeze-drying using graphene oxide and methacrylic acid as substrates. Then, the p(MAA)/GOA were applied as solid-phase extraction adsorbents to extract DA and l-Tyr from urine samples, followed by quantification using high performance liquid chromatography (HPLC). The p(MAA)/GOA showed better adsorption performance for DA and l-Tyr than commercial adsorbents, likely as a result of the strong adsorption of the target analytes via π-π and hydrogen bonding interactions. Further, the developed method had good linearity (r > 0.9990) at concentrations of DA and l-Tyr of 0.075-2.0 and 0.75-20.0 µg mL-1, respectively, as well as a limit of detection of 0.018-0.048 µg mL-1, limit of quantitation of 0.059-0.161 µg mL-1, spiked recovery of 91.1-104.0%, and interday precision of 3.58-7.30%.The method was successfully applied to determine DA and l-Tyr in the urine samples of patients suffering from depression, demonstrating its potential for clinical applications.

Zoning laminectomy for the treatment of ossification of the thoracic ligamentum flavum.

OBJECTIVE: Spinal cord injury is a common occurrence during spinal surgery. In this study, we proposed a zoning laminectomy, which could reduce the incidence of nerve injury. We also discussed the safety and clinical efficacy of the zoning laminectomy for thoracic ossification of the ligamentum flavum (TOLF). METHODS: Forty-five patients with TOLF who underwent zoning laminectomy from October 2016 to February 2020 were included in the retrospective analysis. The Japan Orthopedic Association (JOA) score was used to evaluate clinical outcomes. Meanwhile, the occurrence of complications was recorded. RESULTS: All 45 patients underwent the operation successfully, and the mean follow-up period was 25.3 months, the mean operation time was 160.2 min, the average blood loss was 474.2 ml, and the average hospital time was 8.0 days. At the final evaluation, the JOA score was significantly higher than the preoperative JOA score (P < 0.001) and the overall recovery rate of the JOA score averaged 69.6%. Seventeen patients were graded as excellent, twenty-six as good, and two as fair. The complications included dural tears in nine patients (20.0%), cerebrospinal fluid leakage in seven patients (15.6%), deep infection in one patient (2.2%), and epidural hematoma in one patient (2.2%). All patients recovered well after treatment. Besides, there was no neurological deterioration and thoracic kyphosis occurred. CONCLUSIONS: Zoning laminectomy adopts a phased resection from "safe zone" to "danger zone" and defines the safe removal range of the lamina, which reduces the risks of spinal cord injury caused by instrument manipulation. Therefore, it is a safe and effective surgical option.