[Applications of native mass spectrometry and ultraviolet photodissociation in protein structure and interaction analysis].

Dynamic changes in the structures and interactions of proteins are closely correlated with their biological functions. However, the precise detection and analysis of these molecules are challenging. Native mass spectrometry (nMS) introduces proteins or protein complexes into the gas phase by electrospray ionization, and then performs MS analysis under near-physiological conditions that preserve the folded state of proteins and their complexes in solution. nMS can provide information on stoichiometry, assembly, and dissociation constants by directly determining the relative molecular masses of protein complexes through high-resolution MS. It can also integrate various MS dissociation technologies, such as collision-induced dissociation (CID), surface-induced dissociation (SID), and ultraviolet photodissociation (UVPD), to analyze the conformational changes, binding interfaces, and active sites of protein complexes, thereby revealing the relationship between their interactions and biological functions. UVPD, especially 193 nm excimer laser UVPD, is a rapidly evolving MS dissociation method that can directly dissociate the covalent bonds of protein backbones with a single pulse. It can generate different types of fragment ions, while preserving noncovalent interactions such as hydrogen bonds within these ions, thereby enabling the MS analysis of protein structures with single-amino-acid-site resolution. This review outlines the applications and recent progress of nMS and UVPD in protein dynamic structure and interaction analyses. It covers the nMS techniques used to analyze protein-small-molecule ligand interactions, the structures of membrane proteins and their complexes, and protein-protein interactions. The discussion on UVPD includes the analysis of gas-phase protein structures and interactions, as well as alterations in protein dynamic structures, and interactions resulting from mutations and ligand binding. Finally, this review describes the future development prospects for protein analysis by nMS and new-generation advanced extreme UV light sources with higher brightness and shorter pulses.

The EC50 of propofol with different doses of dexmedetomidine during gastrointestinal endoscopy: A double-blind, placebo-controlled trial.

PURPOSE: The goal of this study was to evaluate the dose-response relationship between dexmedetomidine and propofol in sedating patients and to determine the optimal dosage of dexmedetomidine during gastrointestinal endoscopy. METHODS: One hundred fifty patients were divided into 5 groups, each receiving a loading dose of dexmedetomidine (0.4, 0.6, 0.8, 1.0 µg/kg) or saline, with propofol for sedation. The median effective concentration (EC50) of propofol was calculated using the modified Dixon up-and-down approach. Adverse effects, vital signs, procedure, and recovery times were recorded. RESULTS: The EC50 of propofol in groups NS, D0.4, D0.6, D0.8, and D1.0 were 3.02, 2.44, 1.97, 1.85, and 1.83 µg/mL, respectively. Heart rate in the dexmedetomidine groups decreased more than the NS group (P < .001). The mean arterial pressure (MAP) in the NS group experienced a decline compared to groups D0.8 and D1.0 when the plasma concentration and effect-site concentration reached equilibrium. Additionally, the respiratory rate was found to be lower in groups NS, D0.4, D0.6, and D0.8 (P < .05). Recovery time in groups D0.8 and D1.0 was longer than the NS group (P < .05). Bruggemann comfort scales score was higher in group D1.0 (P < .05). No significant difference was found in the incidences of hypotension and bradycardia, and the dose of ephedrine and atropine. Respiratory depression was significantly reduced in groups D0.8 and D1.0 compared to the NS group. CONCLUSION: A single dose of 0.6 to 0.8 µg/kg of dexmedetomidine should be recommended in combination with propofol for gastrointestinal endoscopy. And the EC50 of propofol is 1.97 to 1.85 µg/mL.

Comparison of intravenous butorphanol vs. tramadol for post-spinal anesthesia shivering: a meta-analysis and systematic review.

Background: Patients often experience shivering after spinal anesthesia. In recent years, more and more studies have compared the efficacy and side effects of intravenous butorphanol and tramadol in the treatment of shivering after spinal anesthesia. Therefore, we conducted a MATE analysis and systematic review to compare the efficacy and side effects of butorphanol vs. tramadol in the treatment of shivering after spinal anesthesia. Methods: PubMed, Cochrane Library, and Embase databases were searched for randomized controlled trials (RCTs) from inception to 30 December 2022, comparing the effects of butorphanol vs. tramadol for the control of shivering after spinal anesthesia. Data assessment and collection were analyzed using the Review Manager 5.4 software. Results: Five randomized controlled trials involving 302 adult patients were included in this meta-analysis. The results showed that butorphanol has a shorter time to cease shivering (standardized mean difference (SMD) = -0.53; 95% confidence interval (CI) [-0.89, -0.17], P = 0.004, I2 = 0%), a higher rate of cessation of shivering within 1 min after administering the study drugs (relative risk (RR), 1.69; 95% CI [1.15,2.48], P = 0.008, I2 = 0%), and higher incidences of sedation (RR, 2.98; 95% CI [2.11, 4.21], P <0.00001, I2 = 0%), compared with tramadol. Conclusion: In the treatment of shivering after spinal anesthesia, butorphanol has a shorter onset time and a higher rate of cessation of shivering within 1 min after the study drugs were administered than tramadol. Therefore, butorphanol is superior to tramadol in the treatment of shivering after spinal anesthesia.

Specific pupylation as IDEntity reporter (SPIDER) for the identification of protein-biomolecule interactions.

Protein-biomolecule interactions play pivotal roles in almost all biological processes. For a biomolecule of interest, the identification of the interacting protein(s) is essential. For this need, although many assays are available, highly robust and reliable methods are always desired. By combining a substrate-based proximity labeling activity from the pupylation pathway of Mycobacterium tuberculosis and the streptavidin (SA)-biotin system, we developed the Specific Pupylation as IDEntity Reporter (SPIDER) method for identifying protein-biomolecule interactions. Using SPIDER, we validated the interactions between the known binding proteins of protein, DNA, RNA, and small molecule. We successfully applied SPIDER to construct the global protein interactome for m6A and mRNA, identified a variety of uncharacterized m6A binding proteins, and validated SRSF7 as a potential m6A reader. We globally identified the binding proteins for lenalidomide and CobB. Moreover, we identified SARS-CoV-2-specific receptors on the cell membrane. Overall, SPIDER is powerful and highly accessible for the study of protein-biomolecule interactions.

[Application of Iron and Sulfate-Modified Biochar in Phosphorus Removal from Water].

The excessive discharge of phosphate into natural water has caused serious environmental problems. Adsorption is an efficient technology for phosphorus removal from water. In this study, a novel biochar modified by chitosan, ferrous sulfate, and sodium sulfide was synthesized and performed well in phosphorus adsorption. The results of batch experiments showed that the optimum synthesized composite could adsorb 49.32 mg·g-1 of phosphate at 298 K. Meanwhile, the simulation results showed better fitting with the pseudo-second-order model and Langmuir model. The adsorption rate was dominated by three-dimensional diffusion within the inner pores. The adsorption process was defined as physic/chemisorption, while the adsorption mechanism was concluded to be electrostatic adsorption, porous filling, surface chemical precipitation, hydrogen binding, and the ligand effect. This study showed that the composite is effective in phosphorus removal from water, and we anticipate that our research will offer guidelines for adsorbent design and reveal the adsorption mechanism.

[Synthesis of Magnetic Iron Modifying Biochar for Ammonia Nitrogen Removal from Water].

A significant factor for eutrophication is the excessive discharge of ammonia nitrogen. Unfortunately, traditional methods to remove ammonia nitrogen are ineffective when facing gradually strict rules. Recently, adsorption has gained interest from scholars due to its efficiency and safety in ammonia nitrogen treatment. In this study, a novel biochar, modified with magnetic iron, was synthesized through co-precipitation, which performed well in ammonia nitrogen removal. The maximum adsorption amount at 293 K of the composite that was synthesized at 80℃(MB80) was 17.52 mg·g-1. Meanwhile, the simulation results displayed a good fitting with the pseudo second order model and Langmuir model. Additionally, the adsorption mechanism could be attributed to electrostatic adsorption, porous filling, ion exchange, and hydrogen bonding. Noticeably, MB80 maintained a good performance after 5 cycles, with desirable adsorption amount of 3.18 mg·g-1. This study aimed to provide an efficient method to treat ammonia nitrogen as well as a new way to dispose of municipal sludge.

Inhibition of human thrombin by the constituents of licorice: inhibition kinetics and mechanistic insights through in vitro and in silico studies.

Thrombin inhibition therapy is a practical strategy to reduce thrombotic and cardiovascular risks via blocking the formation of blood clots. This study aimed to identify naturally occurring thrombin inhibitors from licorice (one of the most popular edible herbs), as well as to investigate their inhibitory mechanisms. Among all tested licorice constituents, licochalcone A was found as the most efficacious agent against human thrombin (IC50 = 7.96 µM). Inhibition kinetic analyses demonstrated that licochalcone A was a mixed inhibitor against thrombin-mediated Z-Gly-Gly-Arg-AMC acetate hydrolysis, with a K i value of 12.23 µM. Furthermore, mass spectrometry-based chemoproteomic assays and molecular docking simulations revealed that licochalcone A could bind to human thrombin at both exosite I and the catalytic site. In summary, our findings demonstrated that the chalcones isolated from licorice were a new class of direct thrombin inhibitors, also suggesting that licochalcone A was a promising lead compound for developing novel anti-thrombotic agents.

Biflavones from Ginkgo biloba as inhibitors of human thrombin.

Ginkgo Biloba leaf extract has been widely used for the prevention and treatment of thrombosis and cardiovascular disease in both eastern and western countries, but the bioactive constituents and the underlying mechanism of anti-thrombosis have not been fully characterized. The purpose of this study was to investigate the inhibitory effects of major constituents in Ginkgo biloba on human thrombin, a key serine protease regulating the blood coagulation cascade and the processes of thrombosis. To this end, a fluorescence-based biochemical assay was used to assay the inhibitory effects of sixteen major constituents from Ginkgo biloba on human thrombin. Among all tested natural compounds, four biflavones (ginkgetin, isoginkgetin, bilobetin and amentoflavone), and five flavonoids (luteolin, apigenin, quercetin, kaempferol and isorhamnetin) were found with thrombin inhibition activity, with the IC50 values ranging from 8.05 µM to 82.08 µM. Inhibition kinetic analyses demonstrated that four biflavones were mixed inhibitors against thrombin-mediated Z-GGRAMC acetate hydrolysis, with the Ki values ranging from 4.12 µM to 11.01 µM. Molecular docking method showed that the four biflavones could occupy the active cavity with strong interactions of salt bridges and hydrogen bonds. In addition, mass spectrometry-based lysine labeling reactivity assay suggested that the biflavones could bind on human thrombin at exosite I rather than exosite II. All these findings suggested that the biflavones in Ginkgo biloba were naturally occurring inhibitors of human thrombin, and these compounds could be used as lead compounds for the development of novel thrombin inhibitors with improved efficacy and high safety profiles.

Real-Time Tracking the Synthesis and Degradation of Albumin in Complex Biological Systems with a near-Infrared Fluorescent Probe.

In this study, a novel fluorescent detection system for biological sensing of human albumin (HA) was developed on the basis of the pseudoesterase activity and substrate preference of HA. The designed near-infrared (NIR) fluorescent probe (DDAP) could be effectively hydrolyzed by HA, accompanied by significant changes in both color and fluorescence spectrum. The sensing mechanism was fully investigated by fluorescence spectroscopy, NMR, and mass spectra. DDAP exhibited excellent selectivity and sensitivity toward HA over a variety of human plasma proteins, hydrolases, and abundant biomolecules found in human body. The probe has been successfully applied to measure native HA in diluted plasma samples and the secreted HA in the hepatocyte culture supernatant. DDAP has also been used for fluorescence imaging of HA reabsorption in living renal cells, and the results show that the probe exhibits good cell permeability, low cytotoxicity and high imaging resolution. Furthermore, DDAP has been successfully used for real-time tracking the uptaking and degradation of albumin in ex vivo mouse kidney models for the first time. All these results clearly demonstrated that DDAP-based assay held great promise for real-time sensing and tracking HA in complex biological systems, which would be very useful for basic researches and clinical diagnosis of HA-associated diseases.

[Pathomorphological change of the atlanto-occipital segment of vertebral artery related with cervical vertigo].

OBJECTIVE: To explore the pathomorphological change of the atlanto-occipital segment of vertebral artery (V3 part) related with cervical vertigo. METHODS: From June 1999 to November 2011, the pathomorphological change of the atlanto-occipital segment of vertebral artery were observed in 1680 patients with cervical vertigo using 3D-CTA technology. The clinical data of these patients were analyzed. There were 783 males and 897 females, aged from 22 to 70 years old with an average of 52.8 years old. Doppler examination showed vertebral basilar artery flow velocity to speed up or slow down. RESULTS: The blood vessel of 3360 branches were detected in 1680 patients and 2778 branches were detected out vascular anomaly. And 829 branches were in V1 segment, 421 were in V2, 328 were in V3, 1190 were in V4. The pathomorphological changes in the atlanto-occipital segment (V3) of vertebral artery included angiospasm, congenital absence, abnormal exit, localized stenosis. CONCLUSION: There are 4 kinds of pathomorphological changes in the atlanto-occipital segment of vertebral artery related with cervical vertigo. The 3D-CTA result can be used to judge prognosis and adopt reasonable treatment for the patients.

[Finite element method analysis of anteflexion traction on various angles for the treatment of cervical spine].

OBJECTIVE: To analyze the data of angle variation on traction based on a finite element model of complete cervical spine with straight physiological curvature, and try to give experimental reference and suggestion in treating cervical spondylosis. METHODS: A 43-year-old female patient with straight cervical spine was chosen and the CT scan data were collected. By using specially designed modeling system, a high quality finite element model of complete cervical spine with straight physiological curvature is generated,which included ligament and muscle according to anatomy. After the model was confirmed, traction was loaded with angle 0 degree, anterior 5 degrees, 10 degrees, 15 degrees, 20 degrees, 25 degrees, to observe the data of distance change on between adjacent intervertebral foramen, processus articularis, uncovertedral joint, intervertebral discs, and stress of anulus fibrosus and nucleus pulposus. RESULTS: When the angle was 0 degrees-15 degrees, the distance between intervertebral foramen, Luschka joint and processus articularis posterioris was enlarged, the tensile stress was adequate and compressive stress was small. It met the clinical requests. CONCLUSION: 0 degree-15 degrees anterior position is suggested for the treatment of cervical spondylosis.

[Analysis on the prognostic factors in patients with large hepatocarcinoma treated by shentao ruangan pill and hydroxycamptothecine].

OBJECTIVE: To observe the effect of intervention therapy with Shentao Ruangan pill (SRP) and hydroxycamptothecine (HCPT) in treating 85 patients with middle-advanced large hepatocarcinoma, and to analyze the factors that could affect the prognosis. METHODS: Eighty-five patients were randomly divided into the treated group (n = 52) and the control group (n = 33). The treated group was treated by oral taking of SRP combined with local perfusion of HCPT through hepatic artery catheterization, while to the control group, the conventional therapy, transcatheter arterial chemoembolization (TACE) was conducted for control. The clinical efficacy of treatment in the two groups was evaluated by the change of tumor size, the factors related with prognosis were analyzed using Cox proportional hazards model and the analysis of survival conducted by Kaplan-Meier method. RESULTS: (1) The tumor size reducing rate in the treated group was 19.2% and the tumor size stabilizing rate was 82.7%, while those in the control group was 21.2% and 81.8% respectively, comparison of the criteria between the two groups showed insignificant difference (P > 0.05); (2) The median survival time, 0.5- year, 1- year and 2- year survival rate in the treated group was 326 days, 80.95%, 41.39% and 12.42% respectively, those in the control group was 262 days, 64.29%, 25.00% and 8.33% respectively, comparison between the two groups showed significant difference (P < 0.05); (3) Among the 3 TCM types in patients, the survival time and rates in patients of Gan-excess with Pi-deficiency type was similar to those in patients of Gan-heat with blood stasis type showing insignificant difference (P > 0.05), but as compared with those in patients of Gan-Shen Yin-deficiency type, the difference was significant (P < 0.05) ; (4) Beneficial factor to the prognosis were therapeutic method, that used in the treated group was superior to that used in the control group. The risk factors to the prognosis were TCM type, clinical stage and liver function. Patients of Gan-excess with Pi-deficiency type had the optimal prognosis, those of Gan-heat with blood stasis type the next and of Gan-Shen Yin-deficiency the worst. The later the clinical stage and the worse the Child-Pugh grade of liver function was, the worse the prognosis would be. CONCLUSION: (1) SRP combined with HCPT intervention treatment is superior to the simple TACE treatment in elevating patients' survival rate and time; (2) There are some relations between TCM types and prognosis; (3) Local Chinese drug therapy combined with systemic therapy could be one of the effective measures of non-operational therapy in treating large hepatocarcinoma.