Advances in succinic acid production: the enhancement of CO2 fixation for the carbon sequestration benefits.

Succinic acid (SA), one of the 12 top platform chemicals produced from biomass, is a precursor of various high value-added derivatives. Specially, 1 mol CO2 is assimilated in 1 mol SA biosynthetic route under anaerobic conditions, which helps to achieve carbon reduction goals. In this review, methods for enhanced CO2 fixation in SA production and utilization of waste biomass for SA production are reviewed. Bioelectrochemical and bioreactor coupling systems constructed with off-gas reutilization to capture CO2 more efficiently were highlighted. In addition, the techno-economic analysis and carbon sequestration benefits for the synthesis of bio-based SA from CO2 and waste biomass are analyzed. Finally, a droplet microfluidics-based high-throughput screening technique applied to the future bioproduction of SA is proposed as a promising approach.

Combining directed evolution with high cell permeability for high-level cadaverine production in engineered Escherichia coli.

The biosynthesis of cadaverine from lysine is an environmentally promising technology, that could contribute to a more sustainable approach to manufacturing bio-nylon 5X. However, the titer of biosynthesized cadaverine has still not reached a sufficient level for industrial production. A powerful green cell factory was developed to enhance cadaverine production by regulating lipopolysaccharide (LPS) genes and improving membrane permeability. Firstly, 10 LPS mutant strains were constructed and the effect on the growth was investigated. Then, the lysine decarboxylase (CadA) was overexpressed in 10 LPS mutant strains of Escherichia coli MG1655 and the ability to produce cadaverine was compared. Using 20.0 g L-1 of L-lysine hydrochloride (L-lysine-HCl) as the substrate for the biotransformation reaction, Cad02 and Cad06 strains exhibited high production levels of cadaverine, with 8.95 g L-1 and 7.55 g L-1 respectively while the control strain Cad00 only 4.92 g L-1 . Directed evolution of CadA was also used to improve its stability under alkaline conditions. The cadaverine production of the Cad02-M mutant stain increased by 1.86 times at pH 8.0. Finally, the production process was scaled up using recombinant whole cells as catalysts, achieving a high titer of 211 g L-1 cadaverine (96.8%) by fed-batch bioconversion. This study demonstrates the potential role of LPS in enhancing the efficiency of mass transfer between substrate and enzymes in vivo by increasing cell permeability. The results indicate that the argumentation of cell permeability could not only significantly enhance the biotransformation efficiency of cadaverine, but also provide a universally applicable, straightforward, environment-friendly, and cost-effective method for the biosynthesis of other high-value chemicals.

[A new biosynthesis route for production of 5-aminovalanoic acid, a biobased plastic monomer].

5-aminovalanoic acid (5AVA) can be used as the precursor of new plastics nylon 5 and nylon 56, and is a promising platform compound for the synthesis of polyimides. At present, the biosynthesis of 5-aminovalanoic acid generally is of low yield, complex synthesis process and high cost, which hampers large-scale industrial production. In order to achieve efficient biosynthesis of 5AVA, we developed a new pathway mediated by 2-keto-6-aminohexanoate. By combinatory expression of L-lysine α-oxidase from Scomber japonicus, α-ketoacid decarcarboxylase from Lactococcus lactis and aldehyde dehydrogenase from Escherichia coli, the synthesis of 5AVA from L-lysine in Escherichia coli was achieved. Under the initial conditions of glucose concentration of 55 g/L and lysine hydrochloride of 40 g/L, the final consumption of 158 g/L glucose and 144 g/L lysine hydrochloride, feeding batch fermentation to produce 57.52 g/L of 5AVA, and the molar yield is 0.62 mol/mol. The new 5AVA biosynthetic pathway does not require ethanol and H2O2, and achieved a higher production efficiency as compared to the previously reported Bio-Chem hybrid pathway mediated by 2-keto-6-aminohexanoate.

The safety and efficacy of tPA intravenous thrombolysis for treating acute ischemic stroke patients with a history of cerebral hemorrhage.

Alteplase (tPA) intravenous thrombolysis is an effective treatment for acute ischemic stroke (AIS) when administered within 4.5 h of initial stroke symptoms. Here, its safety and efficacy were evaluated among AIS patients with a previous history of cerebral hemorrhage. Patients who arrived at the hospital within 4.5 h of initial stroke symptoms and who were treated with tPA intravenous thrombolysis or conventional therapies were analyzed. The 90-day modified Rankin scale (90-d mRS) was used alongside mortality and incidence of symptomatic intracerebral hemorrhage (SICH) rates to evaluate the curative effect of these therapies. Among 1,694 AIS patients, 805 patients were treated with intravenous thrombolysis, including patients with (n=793) or without (n=12) a history of cerebral hemorrhage, and the rate of incidence of SICH significantly differed between them (8.3 vs 4.3%, P=0.039). No significant difference was found in 90-d mRS measurements (41.7 vs 43.6%, P=0.530) and 90-d mortality rates (8.3 vs 6.5%, P=0.946). A total of 76 AIS patients with a history of cerebral hemorrhage received tPA thrombolytic therapy (n=12) or conventional therapy (n=64), and a significant difference was noted in the 90-d mRS scores between the two groups (41.7 vs 23.4%, P=0.029), while no significant difference was found in SICH measurements (8.3 vs 4.6%, P=0.610) and 90-d mortality rates (8.3 vs 9.4%, P=0.227). A history of cerebral hemorrhage is not an absolute contraindication for thrombolytic therapy; tPA intravenous thrombolysis does not increase SICH measurements and mortality rates in patients with a history of cerebral hemorrhage, and they may benefit from thrombolytic therapy.

Dual Antiplatelet Therapy after Intravenous Thrombolysis for Acute Minor Ischemic Stroke.

OBJECTIVE: To verify the efficacy and safety of dual antiplatelet therapy after intravenous thrombolysis for acute minor ischemic stroke (AMIS). METHODS: AMIS patients who received recombinant tissue plasminogen activator (rt-PA) intravenous thrombolysis from January to October 2018 were retrospectively analyzed and divided into the aspirin (ASP) and ASP + clopidogrel (ASP-CLO) groups based on the type of antiplatelet therapy to compare the rates of good clinical outcome, symptomatic intracranial hemorrhage (SICH) after thrombolysis, and mortality in 90 days. RESULTS: A total of 207 patients were included (group ASP, 105 patients; group ASP-CLO, 102 patients). There was no significant difference in the baseline clinical data between the 2 groups. The -90-day modified Rankin scale scores (66.7 vs. 82.4%, p = 0.009) showed a statistically significant difference, but SICH (1.0 vs. 1.0%, p = 0.917) and 90-day mortality (1.9 vs. 1.0%, p = 0.585) showed no significant difference between the 2 groups. CONCLUSIONS: Short-term (21 days) dual antiplatelet therapy after rt-PA intravenous thrombolysis for AMIS can improve the prognosis, reduce the risk of stroke recurrence, without increasing the risk of bleeding and mortality.

The safety and efficacy of tPA intravenous thrombolysis for treating acute ischemic stroke patients with a history of cerebral hemorrhage

Alteplase (tPA) intravenous thrombolysis is an effective treatment for acute ischemic stroke (AIS) when administered within 4.5 h of initial stroke symptoms. Here, its safety and efficacy were evaluated among AIS patients with a previous history of cerebral hemorrhage. Patients who arrived at the hospital within 4.5 h of initial stroke symptoms and who were treated with tPA intravenous thrombolysis or conventional therapies were analyzed. The 90-day modified Rankin scale (90-d mRS) was used alongside mortality and incidence of symptomatic intracerebral hemorrhage (SICH) rates to evaluate the curative effect of these therapies. Among 1,694 AIS patients, 805 patients were treated with intravenous thrombolysis, including patients with (n=793) or without (n=12) a history of cerebral hemorrhage, and the rate of incidence of SICH significantly differed between them (8.3 vs 4.3%, P=0.039). No significant difference was found in 90-d mRS measurements (41.7 vs 43.6%, P=0.530) and 90-d mortality rates (8.3 vs 6.5%, P=0.946). A total of 76 AIS patients with a history of cerebral hemorrhage received tPA thrombolytic therapy (n=12) or conventional therapy (n=64), and a significant difference was noted in the 90-d mRS scores between the two groups (41.7 vs 23.4%, P=0.029), while no significant difference was found in SICH measurements (8.3 vs 4.6%, P=0.610) and 90-d mortality rates (8.3 vs 9.4%, P=0.227). A history of cerebral hemorrhage is not an absolute contraindication for thrombolytic therapy; tPA intravenous thrombolysis does not increase SICH measurements and mortality rates in patients with a history of cerebral hemorrhage, and they may benefit from thrombolytic therapy.

KB-R7943 restores endothelium-dependent relaxation induced by advanced glycosylation end products in rat aorta.

OBJECTIVES: The aims of this study were to examine the effects of KB-R7943, an inhibitor of Na(+)/Ca(2+) exchanger, on impaired endothelium-dependent relaxation (EDR) induced by advanced glycosylation end products (AGE) in isolated rat aorta. METHODS: Both acetylcholine (ACh)-induced EDR and sodium nitroprusside (SNP)-induced endothelium-independent relaxation (EIR) were measured after the rings were exposed to AGE in the absence and presence of KB-R7943. RESULTS: Co-incubation of aortic rings with AGE (0.1 g/L) for 24 h resulted in a significant inhibition of EDR, but had no effects on EIR. After incubation of the rings in the co-presence of KB-R7943 (0.1-10 µM) with AGE for 24 h, KB-R7943 (10 µM) significantly attenuated impaired EDR. Superoxide dismutase (200 U/mL) and l-arginine (3mM) could ameliorate the impairment of EDR caused by AGE, whereas d-arginine (3mM) had no effect on EDR. Similarly, AGE decreased superoxide dismutase (SOD) activity and the release of nitric oxide (NO), and increased superoxide anion (O(2)(.-)) production in aortic tissue. KB-R7943 (10 µM) significantly decreased O(2)(.-) production and increased SOD activity and the NO release. CONCLUSIONS: These results suggest that KB-R7943 attenuated the impairment of EDR elicited by AGE partially through scavenging oxygen free radicals.

Sarpogrelate inhibits the expression of ICAM-1 and monocyte-endothelial adhesion induced by high glucose in human endothelial cells.

Hyperglycemia is the major cause of diabetic angiopathy. Sarpogrelate hydrochloride is an antiplatelet drug, and expected to be useful in the treatment of chronic arterial occlusive diseases. The aim of our study was to evaluate the possible effects of sarpogrelate hydrochloride on adhesion molecule expression and its underlying mechanism in the prevention and treatment of cardiovascular disorders. Intercellular adhesion molecule-1 (ICAM-1) expression and superoxide dismutase (SOD) activity were determined after endothelial cells were exposed to high glucose in the absence and presence of sarpogrelate hydrochloride. Coincubation of endothelial cells with high glucose for 24 h resulted in a significant increase of monocyte-endothelial cell adhesion and the expression of ICAM-1 (P < 0.01). These effects were abolished by sarpogrelate hydrochloride and sarpogrelate hydrochloride significantly increased SOD activities (40 ± 8 vs. 47 ± 7, n = 8, P < 0.01). The low dose sarpogrelate group (0.1 µM) had significantly higher monocyte-endothelial cell adhesion and the expression of ICAM-1 than medium dose sarpogrelate group (1.0 µM) and high dose sarpogrelate group (10.0 µM) (P < 0.05 for comparison among three groups and P < 0.01 for difference between low and high dose sarpogrelate groups). These findings suggested that sarpogrelate hydrochloride was able to protect vascular endothelium from dysfunction induced by high glucose.