Systems engineering Escherichia coli for efficient production p-coumaric acid from glucose.

P-coumaric acid (p-CA), a pant metabolite with antioxidant and anti-inflammatory activity, is extensively utilized in biomedicine, food, and cosmetics industry. In this study, a synthetic pathway (PAL) for p-CA was designed, integrating three enzymes (AtPAL2, AtC4H, AtATR2) into a higher l-phenylalanine-producing strain Escherichia coli PHE05. However, the lower soluble expression and activity of AtC4H in the PAL pathway was a bottleneck for increasing p-CA titers. To overcome this limitation, the soluble expression of AtC4H was enhanced through N-terminal modifications. And an optimal mutant, AtC4HL373T/G211H, which exhibited a 4.3-fold higher kcat/Km value compared to the wild type, was developed. In addition, metabolic engineering strategies were employed to increase the intracellular NADPH pool. Overexpression of ppnk in engineered E. coli PHCA20 led to a 13.9-folds, 1.3-folds, and 29.1% in NADPH content, the NADPH/NADP+ ratio and p-CA titer, respectively. These optimizations significantly enhance p-CA production, in a 5-L fermenter using fed-batch fermentation, the p-CA titer, yield and productivity of engineered strain E. coli PHCA20 were 3.09 g/L, 20.01 mg/g glucose, and 49.05 mg/L/h, respectively. The results presented here provide a novel way to efficiently produce the plant metabolites using an industrial strain.

Synthesis and initial evaluation of radioiodine-labelled deuterated tropane derivatives targeting dopamine transporter.

The dopamine transporter (DAT) is closely related to a variety of neurological disorders including Parkinson's disease (PD) and other neurodegenerative diseases. In vivo imaging of DAT with radio-labelled tracers has become a powerful technique in related disorders. The radioiodine-labelled tropane derivative [123I]FP-CIT ([123I]1a) is widely used in clinical single photon emission computed tomography (SPECT) imaging as a DAT imaging agent. To develop more metabolically stable DAT radioligands for accurate imaging, this work compared two novel deuterated tropane derivatives ([131I]1c-d) with non-deuterated tropane derivatives ([131I]1a-b). [131I]1a-d were obtained in high radiochemical purity (RCP) above 99 % with molar activities of 7.0-10.0 GBq/µmol. The [131I]1a and [131I]1c exhibited relatively higher affinity to DAT (Ki: 2.0-3.12 nM) than [131I]1b and [131I]1d. Biodistribution results showed that [131I]1c consistently exhibited a higher ratio of the target to non-target (striatum/cerebellum) than [131I]1a. Furthermore, metabolism studies indicated that the in vivo metabolic stability of [131I]1c was superior to that of [131I]1a. Ex vivo autoradiography showed that [131I]1c selectively localized on DAT-rich striatal regions and the specific signal could be blocked by DAT inhibitor. These results indicated that [131I]1c might be a potential probe for DAT SPECT imaging in the brain.

Influencing factors of learning sustained attention for nursing students in online settings: A structural equation model.

BACKGROUND: Sustained attention is a key variable affecting nursing students' academic performance during online learning process. However, factors contributing to sustained attention remain to be determined. AIMS: To analyze the path relationships among the influencing factors for nursing students' sustained attention in online learning using a structural equation model. DESIGN: A cross-sectional survey was administered. METHODS: Nursing students from 35 nursing schools in China were invited to participate in this survey study. Once participating in nursing programs and receiving online learning, they were eligible for the study. The data were collected online via the Questionnaire Star platform from March 29 to April 19, 2020. A structural equation modelling (SEM) approach was utilized to analyze the relationships between sustained attention and influencing factors (situational interest, anxiety, cognitive load, technology efficacy and professional identity). Furthermore, multi-group SEM analysis was conducted to examine whether the model equally fitted nursing students in different levels of programs. RESULTS: A total of 1089 nursing students completed the questionnaires. The majority (77.3%) were female and the mean age (SD) was 21.9 (4.4) years. A half (50.3%) were enrolled in the undergraduate programs. Results suggested that situational interest (ß = 0.19, 95% CI: 0.14, 0.24) and anxiety (ß = -0.70, 95% CI: -0.76, -0.64) directly affected sustained attention. Both technology efficacy (ß = 0.22, 95% CI: 0.15, 0.28) and professional identity (ß = 0.20, 95% CI: 0.14, 0.26) had conferred indirect effects on sustained attention through academic emotions (i.e., situational interest and anxiety). The cognitive load directly affected sustained attention (ß = -0.15, 95% CI: -0.20, -0.09) and indirectly affected sustained attention through anxiety (ß = -0.32, 95% CI: -0.37, -0.26). There was no significant difference in the model fit among nursing students in various programs, including diplomatic, associate and bachelor's degree and above programs (∆χ2 = 27.228, p = 0.611). CONCLUSIONS: Technology efficacy, professional identity, situational interest, anxiety and cognitive load are identified as the main elements affecting nursing students' sustained attention. This model is equally suitable for nursing students in different levels of nursing programs. During the process of online learning, students' attributes, emotions and cognition should be considered to help students achieve learning goals in nursing education.

No harm found when the scope of practice of nurse anesthetists is expanded to the whole process of anesthetic care and under indirect supervision of anesthesiologists: A time series study.

BACKGROUND: More and more countries utilize nurse anesthetists as an anesthetic care provider to make up for the insufficiency of anesthesiologists. OBJECTIVE: To examine whether introducing nurse anesthetists with expanded scope of practice to anesthetic care would jeopardize the safety of patients and quality of anesthetic care. DESIGN: This observational study used an interrupted time series design. SETTING(S): A metropolitan teaching cancer hospital located in Southwest China. PARTICIPANTS: 24290 patients with surgical procedures under general anesthesia from January 2015 to December 2017 were included. METHODS: In May 2016, nurse anesthetists with expanded scope of practice were introduced to anesthetic care. Administrative and medical record data were accessed to identify the occurrence of anesthetic outcomes including failed tracheal intubation and inability to ventilate with mask, aspiration, problem with airway in the post-anesthesia care room, hypothermia (temperature ≤ 35°C or chills), unplanned stay in the post-anesthesia care room longer than 3 hours, unexpected intensive care unit admission, reintubation, vascular and cardiopulmonary disorders and death. Statistical process control analysis was conducted to test special cause variation in outcomes over time. RESULTS: Findings demonstrated significant decrease in the proportion of patients staying in the post-anesthesia care room longer than 3 hours and with hypothermia following nurse anesthetists introduced to anesthetic care. Other anesthetic outcomes were not significantly changed. CONCLUSIONS: The results demonstrate that involvement of nurse anesthetists with expanded scope of practice in anesthetic care did not jeopardize patients' safety or quality of anesthesia. Moreover, it may have beneficial impact in preventing prolonged stay in the post-anesthesia care room and hypothermia. Further research is required to examine the impact of involvement of nurse anesthetists in anesthetic care across all clinical contexts.

The effect of family-centered sensory and affective stimulation on comatose patients with traumatic brain injury: A systematic review and meta-analysis.

BACKGROUND: Sensory stimulation has been used in the early rehabilitation of comatose patients with traumatic brain injury, but the effect of sensory stimulation involving family members is unclear. OBJECTIVES: To evaluate the effects of family-centered sensory and affective stimulation on comatose patients with traumatic brain injury and explore the factors that affect the outcomes. DESIGN: A systematic review with a meta-analysis. DATA SOURCES: Electronic databases including PubMed, Web of Science, Google Scholar, Cochrane Library, CINAHL, China National Knowledge Infrastructure, and WanFang were searched from October 2019 to May 2020. REVIEW METHODS: Two reviewers independently assessed eligibility of potential studies and extracted data. Quality of included studies was assessed according to the evaluation criteria of Cochrane Evaluation Manual 5.1.0. Outcome measures of the meta-analysis were the Glasgow Coma Scale scores, the Western Neuro Sensory Stimulation Profile scores, awakening time, and satisfaction rate. To explore whether there was a difference in the effect between variants of the intervention, variables as subgroups were time to start intervention, type of intervention, duration of each intervention, daily frequency of intervention, days of intervention, and patient's area. RESULT: Seventeen randomized controlled trials were included in the review and meta-analysis. Most studies were of medium quality. The improvement of the Glasgow Coma Scale score is significantly greater with the intervention implemented within 24 h compared to the intervention implemented 24 h later (mean difference 3.91, 95% confidence interval 3.44-4.38 vs. mean difference 1.90, 95% confidence interval 1.69-2.12, respectively). The results of subgroup analyses show that auditory stimulation combined with tactile stimulation and multi-sensory stimulation are associated with better outcomes than a single use of auditory stimulation. Studies from Asia report more positive outcomes than those from America (mean difference 1.94, 95% confidence interval 1.73-2.16 vs. mean difference 0.44, 95% confidence interval -0.87-1.75). And the improvement of the Glasgow Coma Scale score with the stimulation performed by family members is greater than that with the stimulation implemented by nurses (mean difference 2.17, 95% confidence interval 1.67-2.66). Besides, it is associated with better awakening time, awakening rate, and satisfaction rate compared to routine care. CONCLUSION: Early family-centered sensory and affective stimulation is more effective than routine care and nurse-implemented sensory stimulation in improving the level of consciousness and cognition of comatose patients with traumatic brain injury, and multi-sensory stimulation is more effective than single stimulation. More studies with larger sample size and high quality in different countries are warranted.