Donor Preactivation-Based Glycan Assembly: from Manual to Automated Synthesis.

Carbohydrates are called the third chain of life. Carbohydrates participate in many important biochemical functions in living species, and the biological information carried by them is several orders of magnitude larger than that of nucleic acids and proteins. However, due to the intrinsic complexity and heterogeneity of carbohydrate structures, furnishing pure and structurally well-defined glycans for functional studies is a formidable task, especially for homogeneous large-size glycans. To address this issue, we have developed a donor preactivation-based one-pot glycosylation strategy enabling multiple sequential glycosylations in a single reaction vessel.The donor preactivation-based one-pot glycosylation refers to the strategy in which the glycosyl donor is activated in the absence of a glycosyl acceptor to generate a reactive intermediate. Subsequently, the glycosyl acceptor with the same anomeric leaving group is added, leading to a glycosyl coupling reaction, which is then iterated to rapidly achieve the desired glycan in the same reactor. The advantages of this strategy include the following: (1) unique chemoselectivity is obtained after preactivation; (2) it is independent of the reactivity of glycosyl donors; (3) multiple-step glycosylations are enabled without the need for intermediate purification; (4) only stoichiometric building blocks are required without complex protecting group manipulations. Using this protocol, a range of glycans including tumor-associated carbohydrate antigens, various glycosaminoglycans, complex N-glycans, and diverse bacterial glycans have been synthesized manually. Gratifyingly, the synthesis of mycobacterial arabinogalactan containing 92 monosaccharide units has been achieved, which created a precedent in the field of polysaccharide synthesis. Recently, the synthesis of a highly branched arabinogalactan from traditional Chinese medicine featuring 140 monosaccharide units has been also accomplished to evaluate its anti-pancreatic-cancer activity. In the spirit of green and sustainable chemistry, this strategy can also be applied to light-driven glycosylation reactions, where either UV or visible light can be used for the activation of glycosyl donors.Automated synthesis is an advanced approach to the construction of complex glycans. Based on the two preactivation modes (general promoter activation mode and light-induced activation mode), a universal and highly efficient automated solution-phase synthesizer was further developed to drive glycan assembly from manual to automated synthesis. Using this synthesizer, a library of oligosaccharides covering various glycoforms and glycosidic linkages was assembled rapidly, either in a general promoter-activation mode or in a light-induced-activation mode. The automated synthesis of a fully protected fondaparinux pentasaccharide was realized on a gram scale. Furthermore, the automated synthesis of large-size polysaccharides was performed, allowing the assembly of arabinans up to an astonishing 1080-mer using the automated multiplicative synthesis strategy, taking glycan synthesis to a new height far beyond the synthesis of nucleic acids (up to 200-mer) and proteins (up to 472-mer).

Evaluation of a 12-hole clock model for improving bronchoscopic skills in simulated normal and difficult airways among anesthesia residents: A randomized controlled study.

BACKGROUND: Simulation-based training is used to improve fiberoptic bronchoscopic skills for novices. We developed a nonanatomical task trainer (named 12-hole clock model) that focused on training manipulation of bronchoscopes. The aim of this study was to evaluate the training effect of this model on bronchoscopic skills and learning interests in simulated normal and difficult airways among anesthesia residents. METHODS: Forty-three anesthesia residents without experience in bronchoscopic intubation were randomly divided into control (n = 22) and intervention groups (n = 21). All participants received standard multimedia learning and a baseline test using a normal airway manikin. Then, the control and intervention groups engaged in 60 minutes of training via a traditional airway manikin or the clock model, respectively. After training, the participants completed bronchoscopic performance assessments in simulated normal and difficult airways, as well as an electronic questionnaire related to the course. RESULTS: During training, the total hands-on time of bronchoscopic practice recorded by trainees' themselves was longer in the intervention group than in the control group (1568 ±â€…478 seconds vs 497 ±â€…172 s, P < .0001). Posttraining, the time required to visualize the carina in simulated normal airways was longer in the intervention group than in the control group (22.0 [18.0, 29.0] vs 14.0 [10.8, 18.3], P < .0001), while it was shorter for simulated difficult airways (24.0 [16.0, 32.0] s vs 27.0 [21.0, 35.5] s, P = .0425). The survey results indicated that confidence in bronchoscopic intubation increased in both groups, without significant differences in satisfaction, acceptance, or perceived difficulty between the groups. However, the interest ratings were higher in the intervention group than in the control group. CONCLUSIONS: The 12-hole clock model is a simple and feasible method for improving bronchoscopic skills and promoting interest among trainees. TRIAL REGISTRATION: NCT05327842 at Clinicaltrials.gov.

The use of transcutaneous electrical acupoint stimulation to reduce opioid consumption in patients undergoing off-pump CABG: a randomized controlled trial.

BACKGROUND: High doses of long-acting opioids were used to facilitate off-pump coronary artery bypass grafting procedure, which may result in opioid-related adverse events after surgery. Transcutaneous electrical acupoint stimulation (TEAS) had been reported to be effective in reducing intraoperative opioids consumption during surgery. The aim of this study is to assess whether TEAS with difference acupoints can reduce the doses of opioid analgesics. METHODS: This was a multicenter, randomized, controlled, double-blind trial. Patients underwent off-pump coronary artery bypass grafting under general anesthesia were enrolled. Eligible patients were randomly and equally grouped into sham acupuncture group (n = 105), regional acupoints combination group (n = 105), or distal-proximal acupoints combination group (n = 105) using a centralized computer-generated randomization system. Transcutaneous electrical acupoint stimulation was applied for 30 min before anesthesia induction. The primary outcome was the doses of sufentanil during anesthesia. Secondary outcomes included the highest postoperative vasoactive-inotropic scores within 24 h, intraoperative propofol consumption, length of mechanical ventilation, duration of cardiac care unit and postoperative hospital stay, incidence of postoperative complications, and mortality within 30 days after surgery. RESULTS: Of the 315 randomized patients, 313 completed the trial. In the modified intention-to-treat analysis, the doses of sufentanil were 303.9 (10.8) µg in the distal-proximal acupoints group, significantly lower than the sham group, and the mean difference was - 34.9 (- 64.9 to - 4.9) µg, p = 0.023. The consumption of sufentanil was lower in distal-proximal group than regional group (303.9 vs. 339.5), and mean difference was - 35.5 (- 65.6 to - 5.5) µg, p = 0.020. The distal-proximal group showed 10% reduction in opioids consumption comparing to both regional and sham groups. Secondary outcomes were comparable among three groups. CONCLUSION: Transcutaneous electrical acupoint stimulation with distal-proximal acupoints combination, compared to regional acupoints combination and sham acupuncture, significantly reduced sufentanil consumption in patients who underwent off-pump coronary artery bypass grafting surgery.