Chemical Evolution of Enzyme-Catalyzed Glycosylation.

ConspectusThe limited availability of structurally well-defined diverse glycans remains a major obstacle for deciphering biological functions as well as biomedical applications of carbohydrates. Despite tremendous progress that has been made in past decades, the synthesis of structurally well-defined complex glycans still represents one of the most challenging topics in synthetic chemistry. Chemical synthesis of glycans is a time-consuming and labor-intensive process that requires elaborate planning and skilled personnel. In contrast, glycosyltransferase-catalyzed enzymatic synthesis provides a more efficient, convenient, low-cost, and sustainable alternative to affording diverse and complex glycans. However, the existing methods are still insufficient to fulfill the increasing demand for specific synthetic glycan libraries necessary for functional glycomics research. This is mainly attributed to the inherent character of the glycan biosynthetic pathway. In nature, there are too many glycosyltransferases involved in the in vivo glycan synthesis, but only a small number of them are available for in vitro enzymatic synthesis. For instance, humans have over 200 glycosyltransferases, but only a few of them could be produced from the conventional bacterial expression system, and most of these membrane-associated enzymes could be overexpressed only in eukaryotic cells. Moreover, the glycan biosynthetic pathway is a nontemplate-driven process, which eventually ends up with heterogeneous glycan product mixtures. Therefore, it is not a practical solution for the in vitro enzymatic synthesis of complex glycans by simply copying the glycan biosynthetic pathway.In the past decade, we have tried to develop a simplified and transformable approach to the enzymatic modular assembly of a human glycan library. Despite the structural complexity of human glycans, the glycoinformatic analysis based on the known glycan structure database and the human glycosyltransferase database indicates that there are approximately 56 disaccharide patterns present in the human glycome and only 16 disaccharide linkages are required to account for over 80% of the total disaccharide fragments, while 35 disaccharide linkages are sufficient to cover over 95% of all disaccharide fragments of human glycome. Regardless of the substrate specificity, if one glycosyltransferase could be used for the synthesis of all of the same glycosidic linkages in human glycome, it will require only a few dozen glycosyltransferases for the assembly of entire human glycans. According to the glycobioinformatics analysis results, we rationally designed about two dozen enzyme modules for the synthesis of over 20 common glycosidic linkages in human glycome, in which each enzyme module contains a glycosyltransferase and a group of enzymes for the in situ generation of a nucleotide-activated sugar donor. By sequential glycosylation using orchestrated enzyme modules, we have completed the synthesis of over 200 structurally well-defined complex human glycans including blood group antigens, O-mannosyl glycans, human milk oligosaccharides, and others. To overcome the product microheterogeneity problem of enzymatic synthesis in the nontemplate-driven glycan biosynthetic pathway, we developed several substrate engineering strategies to control or manipulate the outcome of glycosyltransferase-catalyzed reactions for the precise synthesis of structurally well-defined isomeric complex glycans.

Grazing exclusion is more effective for vegetation restoration and nutrient transfer in the heavily degraded desert steppe.

BACKGROUND: Grazing exclusion is an efficient practice to restore degraded grassland ecosystems by eliminating external disturbances and improving ecosystems' self-healing capacities, which affects the ecological processes of soil-plant systems. Grassland degradation levels play a critical role in regulating these ecological processes. However, the effects of vegetation and soil states at different degradation stages on grassland ecosystem restoration are not fully understood. To better understand this, desert steppe at three levels of degradation (light, moderate, and heavy degradation) was fenced for 6 years in Inner Mongolia, China. Community characteristics were investigated, and nutrient concentrations of the soil (0-10 cm depth) and dominant plants were measured. RESULTS: We found that grazing exclusion increased shoots' carbon (C) concentrations, C/N, and C/P, but significantly decreased shoots' nitrogen (N) and phosphorus (P) concentrations for Stipa breviflora and Cleistogenes songorica. Interestingly, there were no significant differences in nutrient concentrations of these two species among the three degraded desert steppes after grazing exclusion. After grazing exclusion, annual accumulation rates of aboveground C, N, and P pools in the heavily degraded area were the highest, but the aboveground nutrient pools were the lowest among the three degraded grasslands. Similarly, the annual recovery rates of community height, cover, and aboveground biomass in the heavily degraded desert steppe were the highest among the three degraded steppes after grazing exclusion. These results indicate that grazing exclusion is more effective for vegetation restoration in the heavily degraded desert steppe. The soil total carbon, total nitrogen, total phosphorus, available nitrogen, and available phosphorus concentrations in the moderately and heavily degraded desert steppes were significantly decreased after six years of grazing exclusion, whereas these were no changes in the lightly degraded desert steppe. Structural equation model analysis showed that the grassland degradation level mainly altered the community aboveground biomass and aboveground nutrient pool, driving the decrease in soil nutrient concentrations and accelerating nutrient transfer from soil to plant community, especially in the heavily degraded grassland. CONCLUSIONS: Our study emphasizes the importance of grassland degradation level in ecosystem restoration and provides theoretical guidance for scientific formulation of containment policies.

Nutrient reallocation between stem and leaf drives grazed grassland degradation in inner Mongolia, China.

BACKGROUND: Decline in height and aboveground biomass of the plant community are critical indicators of grassland ecosystem degradation. Nutrient reallocation induced by grazing occurs among different organs, which balances the trade-off between growth and defense. However, it is not yet clear how nutrient reallocation strategies affect plant community structure and functions in grazed grasslands. A grazing experiment was conducted in a typical steppe in Inner Mongolia, China. We investigated plant community characteristics and measured plant functional traits of dominant species (Leymus chinensis and Cleistogenes squarrosa) at individual and population levels. Carbon (C), nitrogen (N), phosphorus (P), copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn) concentrations of stem and leaf in the two species were also determined. RESULTS: N, P, Cu, Fe, Mn, and Zn concentrations in leaves and stems of L. chinensis and C. squarrosa significantly increased with grazing intensity, and microelements (Cu, Fe, Mn, and Zn) were more sensitive to grazing. The nutrient slopes of macro- and microelements in leaves were significantly higher than those in stems under grazing, indicating that nutrient resources were preferentially allocated to leaves and enhanced the compensatory growth of leaves in the grazed grassland. With increasing grazing intensity, the aboveground biomass of stems and leaves in the two species significantly decreased, but leaf to stem ratio increased at the individual level, indicating that plants preferentially allocated biomass to leaves under grazing. The increase in leaf to stem ratio due to nutrient reallocation between the two organs significantly reduced height and aboveground biomass at population and community levels, driving grassland ecosystem degradation. CONCLUSION: Our study revealed the driving forces of community structure and function degradation in grazed grasslands from the perspective of nutrient resource allocation, and provided insights into plant adaptation strategies to grazing.

Synthesis and Immunological Evaluation of Pentamannose-Based HIV-1 Vaccine Candidates.

Dense glycosylation and the trimeric conformation of the human immunodeficiency virus-1 (HIV-1) envelope protein limit the accessibility of some cellular glycan processing enzymes and end up with high-mannose-type N-linked glycans on the envelope spike, among which the Man5GlcNAc2 structure occupies a certain proportion. The Man5GlcNAc2 glycan composes the binding sites of some potent broadly neutralizing antibodies, and some lectins that can bind Man5GlcNAc2 show HIV-neutralizing activity. Therefore, Man5GlcNAc2 is a potential target for HIV-1 vaccine development. Herein, a highly convergent and effective strategy was developed for the synthesis of Man5 and its monofluoro-modified, trifluoro-modified, and S-linked analogues. We coupled these haptens to carrier protein CRM197 and evaluated the immunogenicity of the glycoconjugates in mice. The serological assays showed that the native Man5 conjugates failed to induce Man5-specific antibodies in vivo, while the modified analogue conjugates induced stronger antibody responses. However, these antibodies could not bind the native gp120 antigen. These results demonstrated that the immune tolerance mechanism suppressed the immune responses to Man5-related structures and the conformation of glycan epitopes on the synthesized glycoconjugates was distinct from that of native glycan epitopes on gp120.

Distal anastomosis support for bypass grafting with coronary endarterectomy for the severe diseased posterior descending artery.

BACKGROUND: The posterior descending artery is the most common vessel chosen for an endarterectomy, while endarterectomy to the posterior descending artery is associated with decreased graft patency. The purpose of this study was to describe a distal anastomosis support (DAS) technique and retrospectively investigate the effect of DAS on the mid-term graft patency. METHODS: Between January 2016 and December 2018, 200 patients with a PDA severe lesion who underwent off-pump coronary artery bypass (OPCAB) with CE (OPCAB + CE group, n = 95) and OPCAB + CE with DAS for anastomosis of PDA grafted by saphenous vein (SVG) (OPCAB + CE + DAS group, n = 105) were evaluated retrospectively. All patients came back to follow-up visit 6th, 12th, 24th, and 36th postoperative month. The primary endpoint is the graft failure (FitzGibbon B or O) of SVG-PDA on the follow-up CTA or CAG. RESULTS: There was no significant difference in perioperative outcomes. We found significantly improved cumulative graft patency in OPCAB + CE + DAS group at 36 months after operation (84.6% vs 76.5%, p = 0.02). In multivariate Cox regression analysis, plaque length larger than 2 cm (hazard ratio [HR], 13.108, 95% confidence interval [CI], 2.842-60.457, p = 0.001), and peak TNI ⩾70× ULN within 48 hours of surgery (HR, 3.778, 95% CI, 1.453-9.823, p = 0.006) were independent predictors of graft failure, whereas PDA diameter greater than 1.5 mm (HR, 0.231, 95% CI, 0.081-0.654, p = 0.006), and DAS use (HR, 0.336, 95% CI, 0.139-0.812, p = 0.015) were significant protective factors. CONCLUSIONS: Concomitant DAS conferred superior mid-term patency of SVG-PDA. Adding the DAS procedure to OPCAB + CE may be a promising surgical option for patients with a PDA severe lesion, especially when PDA diameter less than 1.5 mm and plaque length greater than 2 cm.

The main trunk of RCA may be the best choice of sequential vein graft distal end-to-side anastomosis.

OBJECTIVE: The purpose of this study was to investigate the effect of different anastomotic positions on the early patency of the distal end-to-side anastomosis of sequential saphenous vein grafts (SVG) in off-pump coronary artery bypass grafting (OPCAB). METHODS: A total of 259 patients who underwent OPCAB between August 2014 and August 2019 and presented for coronary computed tomography angiography (CCTA) to evaluate graft patency at 1 year post-OPCAB were analyzed. There are two kinds of distal end-to-side anastomosis of SVG, to posterior descending artery (PDA) and main trunk of right coronary artery (RCA). In all, 1044 distal coronary anastomoses on 518 grafts which included 180 left internal mammary artery (LIMA) grafts, individual 79 SVG and 259 sequential SVG were assessed using CCTA. The blood flow (BF), pulsatility index (PI), and patency of every anastomosis were recorded. Besides, comprehensive data of SV-PDA and SV-RCA patients was also compared. RESULTS: The mean BF of SV-RCA was significantly higher than that of SV-PDA (31.71 ± 18.60 vs 22.62 ± 14.48, p = 0.001), and the PI value of SV-RCA was significantly lower than that of SV-PDA (2.57 ± 1.17 vs 3.50 ± 1.69, p = 0.001). The patency of RCA system was significantly lower than that of the LAD and the left circumflex system (79.25% vs 90.13%, 90.23% respectively, p = 0.001). In sequential SVG, the patency of SV-PDA was significantly lower than that of SV-RCA (74.01% vs 86.59%, p = 0.001). Although, there was no significant difference in left ventricular ejective fraction, the left ventricular end-diastolic diameter (LVDd) in SV-PDA group was significantly larger than that in SV-RCA (52.67 ± 8.72 mm vs 47.34 ± 7.55, p = 0.001). In addition, the target vessel diameter in SV-PDA group was smaller than that in SV-RCA group (1.52 ± 0.41 mm vs 3.17 ± 0.88 mm, p = 0.001). CONCLUSION: The early patency of sequential SVG end to RCA after OPCAB is generally superior to that of to PDA, especially for patients with large LVDd.

A Redox-Controlled Substrate Engineering Strategy for Site-Specific Enzymatic Fucosylation.

Fucosylation is one of the most common modifications of oligo-N-acetyllactosamine (oligo-LacNAc) glycans. However, none of known fucosyltransferases (FucTs) could install the α1,3-linked fucose to the oligo-LacNAc substrates in a site-specific manner. Here, we report a facile and general redox-controlled substrate engineering strategy for the site-specific α1,3-fucosylation of complex glycans containing multiple LacNAc units. This strategy takes advantage of an operationally simple oxidation enzyme module by using galactose oxidase (GOase) to convert the LacNAc unit into oxidized C6'-aldehyde LacNAc sequence, which is not a good substrate for recombinant α1,3-FucT from Helicobacter pylori strain 26695 (Hpα1,3FucT), enabling the site-specific α1,3-fucosylation at intact LacNAc sites. The general applicability and robustness of this strategy were demonstrated by the synthesis of a variety of structurally well-defined fucosides of linear and branched O- and N-linked glycans.

Cancer Cell Preferential Penetration and pH-Responsive Drug Delivery of Oligorutin.

We report herein a novel delivery system, derived from the facile enzymatic synthesis of oligorutin (OR), for cancer cell targeting and pH-responsive drug delivery. In this study, we demonstrate that OR could preferentially penetrate cancer cells via the lipid raft-mediated endocytosis pathway, and cell membrane cholesterol was critical to the internalization of OR. The accumulation of OR in the tumor region was further confirmed by an in vivo biodistribution study. Considering the tumor-targeting property of OR, a pH-responsive drug delivery system (OR-BTZ) was developed by covalent conjugation of the catechol groups on OR with antitumor drug bortezomib (BTZ) through a pH-sensitive borate ester bond. OR-BTZ exerted cytotoxicity as well as inhibition of the migration and invasion to hepatoma carcinoma cells and showed no apparent cytotoxicity with liver normal cells. The OR-BTZs also presented significant therapeutic efficacy and low systematic toxicity in the murine hepatocellular carcinoma model. To our knowledge, this study presents the first attempt to exploit the potential of oligoflavonoids for cancer cell-targeted drug delivery and will motivate the development of flavonoids and their derivatives as a new type of biomaterials for tumor-targeted therapy.

Enzymatic modular assembly of hybrid Lewis antigens.

The enzymatic synthesis of hybrid Lewis antigens including KH-1 (Lewis y-Lewis x-Lactose, Ley-Lex-Lac), Lewis a-Lewis x-Lactose (Lea-Lex-Lac), and Lewis b-Lewis x-Lactose (Leb-Lex-Lac) has been achieved using a facile enzymatic modular assembly strategy. Starting from a readily available tetrasaccharide, 3 complex hybrid Lewis antigens were achieved in over 40% total yields in less than 5 linear steps of sequential enzymatic glycosylation using 6 enzyme modules. The regio-selective fucosylation was achieved by simply controlling the donor-acceptor ratio. This strategy provides an easy access to these biologically important complex hybrid Lewis antigens at preparative scales.

Adventitial Collagen Crosslink Reduces Intimal Hyperplasia in a Rabbit Arteriovenous Graft Model.

BACKGROUND: Intimal hyperplasia (IH) is the initial lesion of vein graft failure after coronary artery bypass grafting. The weak venous wall is likely one of the primary reasons for IH after exposure to the arterial environment. We investigate whether adventitial collagen cross-link by glutaraldehyde (GA) reinforces the venous wall and then reduces IH. MATERIALS AND METHODS: Adventitial collagen cross-link by 0.3% GA was performed on the rabbit jugular veins. The degree of cross-link was accessed by tensile test. The jugular vein with or without cross-link was implanted into the carotid artery of rabbit. Vein dilatation at the immediate anastomosis and pathological remodeling of vein graft after 4 wk was assessed. RESULTS: Tensile test indicated that the mechanical property of 3-min cross-linked veins more closely resembled that of the carotid artery. In rabbit arteriovenous graft models, 3-min adventitial collagen cross-link limited overdistension (diameter: 3.24 mm versus 4.65 mm, P < 0.01) at the immediate anastomosis and reduced IH (intima thickness: 78.83 µm versus 140.19 µm, P < 0.01) of vein grafts 4 wk after implantation in the cross-link group as compared with the graft group (without cross-link). Compared with the cross-link group, the expression of proliferating cell nuclear antigen and vascular cell adhesion molecule-1 increased significantly at both the mRNA and protein levels within the graft group (P < 0.01), but the expression of smooth muscle-22α decreased significantly (P < 0.01). CONCLUSIONS: Adventitial collagen cross-link by GA increased the vessel stiffness and remarkably reduced IH in a rabbit arteriovenous graft model.

Experimental and Density Functional Theory Studies on 1,1,1,4,4,4-Hexafluoro-2-Butene Pyrolysis.

A series of thermal decomposition experiments were conducted over a temperature range of 873-1073 K to evaluate the thermal stability of 1,1,1,4,4,4-hexafluoro-2-butene (HFO-1336mzz(Z)) and the production of hydrogen fluoride (HF). According to the detected products and experimental phenomena, the thermal decomposition of HFO-1336mzz(Z) could be divided into three stages. Our experimental results showed that HF concentration gradually increased with the elevation of thermal decomposition temperature. In this present study, a total of seven chemical reaction pathways of HFO-1336mzz(Z) pyrolysis were proposed to explore the generated mechanism on products through density functional theory (DFT) with M06-2X/6-311++(d,p) level theory. The thermal decomposition mechanism of pure HFO-1336mzz(Z) was discussed and the possible formation pathways of HF and other main products were proposed.

Chemoenzymatic Synthesis of O-Mannose Glycans Containing Sulfated or Nonsulfated HNK-1 Epitope.

The human natural killer-1 (HNK-1) epitope is a unique sulfated trisaccharide sequence presented on O- and N-glycans of various glycoproteins and on glycolipids. It is overexpressed in the nervous system and plays crucial roles in nerve regeneration, synaptic plasticity, and neuronal diseases. However, the investigation of functional roles of HNK-1 in a more complex glycan context at the molecular level remains a big challenge due to lack of access to related structurally well-defined complex glycans. Herein, we describe a highly efficient chemoenzymatic approach for the first collective synthesis of HNK-1-bearing O-mannose glycans with different branching patterns, and for their nonsulfated counterparts. The successful strategy relies on both chemical glycosylation of a trisaccharide lactone donor for the introduction of sulfated HNK-1 branch and substrate promiscuities of bacterial glycosyltransferases that can tolerate sulfated substrates for enzymatic diversification. Glycan microarray analysis with the resulting complex synthetic glycans demonstrated their recognition by two HNK-1-specific antibodies including anti-HNK-1/N-CAM (CD57) and Cat-315, which provided further evidence for the recognition epitopes of these antibodies and the essential roles of the sulfate group for HNK-1 glycan-antibody recognition.

Redox-Controlled Site-Specific α2-6-Sialylation.

The first bacterial α2-6-sialyltransferase cloned from Photobacterium damselae (Pd2,6ST) has been widely applied for the synthesis of various α2-6-linked sialosides. However, the extreme substrate flexibility of Pd2,6ST makes it unsuitable for site-specific α2-6-sialylation of complex substrates containing multiple galactose and/or N-acetylgalactosamine units. To tackle this problem, a general redox-controlled site-specific sialylation strategy using Pd2,6ST is described. This approach features site-specific enzymatic oxidation of galactose units to mask the unwanted sialylation sites and precisely controlling the site-specific α2-6-sialylation at intact galactose or N-acetylgalactosamine units.

Hepatic PHD2/HIF-1α axis is involved in postexercise systemic energy homeostasis.

Exercise plays an important role in the prevention and treatment of chronic liver disease and associated metabolic disorders. A single bout of exercise induces tissue blood flow redistribution, which decreases splanchnic circulation and leads to physiologic hypoxia in the gastrointestinal system and liver. The transcription factor, hypoxia inducible factor-1α (HIF-1α), and its regulator, prolylhydroxylase 2 (PHD2), play pivotal roles in the response to oxygen flux by regulating downstream gene expression levels in the liver. We hypothesized that exercise increases the HIF-1α levels in the liver, and that the hepatic PHD2/HIF-1α axis is involved in postexercise restoration of systemic energy homeostasis. Through constant O2 consumption, CO2 production, food and water intake, and physical activity detection with metabolic chambers, we observed that one 30-min session of swimming exercise enhances systemic energy metabolism in mice. By using the noninvasive bioluminescence imaging ROSA26 oxygen-dependent domain Luc mouse model, we reveal that exercise increases in vivo HIFα levels in the liver. Intraperitoneal injections of the PHD inhibitor, dimethyloxalylglycine, mimicked exercise-induced HIFα increase, whereas the HIF-1α inhibitor, PX-478, blocked this effect. We next constructed liver-specific knockout (LKO) mouse models with albumin- Cre-mediated, hepatocyte-specific Hif1a and Phd2 deletion. Compared with their controls, Hif1a-LKO and Phd2-LKO mice exhibited distinct patterns of hepatic metabolism-related gene expression profiles. Moreover, Hif1a-LKO mice failed to restore systemic energy homeostasis after exercise. In conclusion, the current study demonstrates that a single bout of exercise disrupts systemic energy homeostasis, increasing the HIF-1α levels in the liver. These findings also provide evidence that the hepatic PHD2/HIF-1α axis is involved in postexercise systemic metabolic homeostasis.-Luo, B., Xiang, D., Wu, D., Liu, C., Fang, Y., Chen, P., Hu, Y.-P. Hepatic PHD2/HIF-1α axis is involved in postexercise systemic energy homeostasis.

Open chest epicardial and transapical endocardial substrate ablation for ventricular tachycardia with left ventricular aneurysm in a porcine model.

BACKGROUND: Endo-epicardial radiofrequency catheter ablation (RFCA) of ventricular tachycardia (VT) as a first-line strategy has been shown to improve outcomes. This study sought to evaluate the feasibility and validity of open-chest epicardial and transapical endocardial substrate ablation for VT with left ventricular aneurysm (LVA) applying to routine cardiac surgery. METHODS: Porcine models of LVA with VT were developed and were divided into a study group (RFCA from the epicardium via direct-view and endocardium via transapical access) and a control group (endocardial RFCA via retrograde transaortic access). Substrate-based mapping and ablation targeting abnormal potentials were performed under thoracotomy. Outcomes, including procedural success and acute freedom from VT, were analysed. RESULTS: Twenty-four of 35 (68.57%) acute myocardial infarction (AMI) pigs developed LVA with VT in a 6-week survival period and were randomly divided into a study group (n=12) and a control group (n=12). All animals in the study group successfully underwent endocardial mapping and ablation by transapical access. The scar size of the endocardium and the left ventricular chamber volume were similar in the two groups. Acute freedom from VT in the study group was remarkably superior to that in the control group (88.33% vs. 58.33%, p=0.04). CONCLUSIONS: Combined, direct epicardial and transapical endocardial substrate mapping and ablation appeared to be feasible and effective for treating VT with LVA under thoracotomy.

Observation of local cardiac electrophysiological changes during off-pump coronary artery bypass grafting using epicardial mapping.

OBJECTIVES: At present, there is no effective method of evaluating the electrophysiological changes in cardiac myocytes during off-pump coronary artery bypass grafting (OPCAB). Therefore, we preliminarily explored the relationship between electrophysiological characteristics and the changes in cardiac function of 24 patients undergoing OPCAB. METHODS: We used the CARTO3 system for epicardial electrophysiological mapping before surgery, during left anterior descending branch anastomosis, diagonal branch anastomosis and after surgery for 24 patients undergoing OPCAB. Data, including local activation time (LAT), bipolar voltage value (BV) and conduction velocity, were processed and analyzed by the system. Intraoperative invasive blood pressure, heart rate and arterial blood gas analysis data were recorded. Continuous electrocardiography (ECG) monitoring was performed three days after surgery. Routine resting myocardial perfusion imaging (MPI) and adenosine stress-gated MPI were performed before surgery. Patients were re-examined before discharge. RESULTS: By analyzing the change in the LAT value, we found that the order of excitation of local myocardial cells changed after surgery. In addition, the LAT change in myocardial cells closer to the anastomosis was more significant. The earliest pacing point on the left anterior descending (LAD) coronary artery territory map was the third point (from the proximal to distal LAD) before OPCAB, but the earliest pacing point moved down to the fourth point (closer to the anastomosis) after the diagonal (DIA) anastomosis was complete. On the DIA territory map, the earliest pacing point was the fourth point before OPCAB; this moved up to the third point (closer to the anastomosis) after DIA bypass grafting. The voltages of all points were increased after myocardial revascularization. Compared with the preoperative period, the third, fourth and fifth points on the LAD territory map increased significantly after LAD anastomosis was complete (p=0.007, p=0.001, p=0.009, respectively). On the DIA territory map, the voltages of the first, second and third points were remarkably increased after completing the DIA anastomosis compared to before OPCAB and after LAD anastomosis completion (p=0.001, p=0.008, p<0.001 and p=0.006, p=0.032, p=0.002, respectively). The average conduction velocity (ACV) of all mapped points increased after OPCAB compared with before OPCAB (p<0.05). Postoperative resting MPI and adenosine stress-gated MPI showed that left ventricular global systolic function improved, the left ventricular ejection fraction (LVEF) increased significantly (p<0.05) and the left ventricular end systolic volume (LVESV) decreased significantly (p<0.05) compared to the preoperative MPI. CONCLUSIONS: Adequate surgical coronary revascularization could lead to more stable electrical activity of local cardiomyocytes, thus, illustrating the specific mechanism of coronary revascularization for improving the cardiac function from an electrophysiological perspective.

Surgical linear ablation for ventricular tachycardia with postinfarction ventricular aneurysm.

BACKGROUND: Left ventricular aneurysm (LVA) might be an arrhythmogenic substrate. Endocardiectomy and cryoablation for ventricular tachycardia (VT) with LVA can cause extensive myocardial damage. We aimed to evaluate the feasibility of surgical radial linear ablation for VT with LVA guided by electrophysiological mapping. MATERIALS AND METHODS: Porcine models of VT with LVA were developed. Endocardial and epicardial substrate mapping during sinus rhythm were performed under thoracotomy. Surgical radial linear ablation was achieved by a bipolar radiofrequency ablation device. Outcomes, including procedural success and acute freedom of VT, were analyzed. RESULTS: Fifteen of 20 pigs developed LVA in a 6-wk survival period. A total of 28 sustained monomorphic VTs were initiated in 13 of 15 pigs (86.67%). The number of potential points captured from the endocardium and epicardium were 319 ± 45 and 358 ± 52 per animal, respectively. The ablative targets containing abnormal potentials were located largely on the border zone of LVA. Eight linear lesions from core to border zone of LVA were achieved per animal in a radial and even manner continuously, and ablation was repeated three times to transect border zone. The acute freedom of VT was 84.62%, P < 0.05. CONCLUSIONS: Surgical linear endo-epicardial ablation seemed to be feasible in a porcine model with VT and LVA.

The application of intraoperative ankle dislocation approach in the treatment of the unstable trimalleolar fractures involving posterior ankle comminuted fracture: a retrospective cohort study.

BACKGROUND: The aim of this study was to introduce a novel intraoperative lateral ankle dislocation approach during surgical treatment for patients with unstable trimalleolar fractures involving posterior ankle comminuted fractures and compare its effects and safety with those with conventional approach. METHODS: From June 2006 to June 2014, 69 patients diagnosed as unstable trimalleolar fractures involving posterior ankle comminuted fracture were included in this study. The patients were divided into intraoperative dislocating ankle group (experimental group) and conventional treatment group (control group) according to surgical modalities. The following parameters including rate of primary healing, healing time, incidence of talus necrosis, incidence of post-traumatic arthritis, functional outcomes according to Baird-Jackson classification system, and any possible complications in two groups were recorded and compared. RESULTS: There were no significant differences regarding the rate of primary healing, healing time and the rate of talus necrosis in two groups (P > 0.05). The incidence of post-traumatic arthritis in experimental and control group were 0 and 24.24% (P = 0.0006), respectively. The rate of excellent and good outcomes were achieved in 91.67% in experimental group and 72.73% in control group (P = 0.038), respectively. CONCLUSIONS: The findings suggest that the intraoperative ankle dislocation approach appears to be a promising surgical option for unstable trimalleolar fractures involving posterior ankle comminuted fracture because it can provide better functional outcomes and lower incidence of post-traumatic arthritis while not compromising primary healing and healing time.

Comparison of minimally invasive arthrolysis vs. conventional arthrolysis for post-traumatic knee stiffness.

BACKGROUND: Minimally invasive surgery in knee arthroplasty can reduce postoperative pain and the rehabilitation period. The goal of this study was to explore the therapeutic effect of minimally invasive arthrolysis in post-traumatic knee stiffness. METHODS: From March 2002 to March 2016, a prospective investigation was performed on seventy post-traumatic knee stiffness patients treated with minimally invasive knee arthrolysis or conventional knee arthrolysis. Curative effect was evaluated according to Judet's criteria. Operative time, incision length, blood loss, the angle of intraoperative release and the final postoperative joint mobility in two groups were compared using the student's t-test. RESULTS: The mean follow up time was 15.37 ± 4.93 months (ranged from 6 months to 2 years).The excellent and good rate was significantly higher in minimally invasive group (95.0%) than conventional arthrolysis group (73.33%) (P < 0.05). Minimally invasive arthrolysis group had shorter operative time (29.38 ± 4.84 vs. 86.00 ± 9.77 min), smaller incision length (6.59 ± 0.86 vs. 20.47 ± 2.91 cm), less intraoperative blood loss (93.25 ± 15.26 vs. 473.33 ± 79.58 ml) and better postoperative final joint activity (104.75 ± 17.87° vs. 90.67 ± 19.64°) compared to conventional arthrolysis group (P < 0.001). CONCLUSIONS: The findings suggest that minimally invasive knee arthrolysis is a much better option for the treatment of post-traumatic knee stiffness due to its advantages such as shorter operative time, little trauma, less blood loss and better postoperative final joint activity. Further studies with a long term of follow-up are wanted.

Chemoenzymatic Assembly of Mammalian O-Mannose Glycans.

O-Mannose glycans account up to 30 % of total O-glycans in the brain. Previous synthesis and functional studies have only focused on the core M3 O-mannose glycans of α-dystroglycan, which are a causative factor for various muscular diseases. In this study, a highly efficient chemoenzymatic strategy was developed that enabled the first collective synthesis of 63 core M1 and core M2 O-mannose glycans. This chemoenzymatic strategy features the gram-scale chemical synthesis of five judiciously designed core structures, and the diversity-oriented modification of the core structures with three enzyme modules to provide 58 complex O-mannose glycans in a linear sequence that does not exceed four steps. The binding profiles of synthetic O-mannose glycans with a panel of lectins, antibodies, and brain proteins were also explored by using a printed O-mannose glycan array.