Stereoselective amino acid synthesis by photobiocatalytic oxidative coupling.

Photobiocatalysis-where light is used to expand the reactivity of an enzyme-has recently emerged as a powerful strategy to develop chemistries that are new to nature. These systems have shown potential in asymmetric radical reactions that have long eluded small-molecule catalysts1. So far, unnatural photobiocatalytic reactions are limited to overall reductive and redox-neutral processes2-9. Here we report photobiocatalytic asymmetric sp3-sp3 oxidative cross-coupling between organoboron reagents and amino acids. This reaction requires the cooperative use of engineered pyridoxal biocatalysts, photoredox catalysts and an oxidizing agent. We repurpose a family of pyridoxal-5'-phosphate-dependent enzymes, threonine aldolases10-12, for the α-C-H functionalization of glycine and α-branched amino acid substrates by a radical mechanism, giving rise to a range of α-tri- and tetrasubstituted non-canonical amino acids 13-15 possessing up to two contiguous stereocentres. Directed evolution of pyridoxal radical enzymes allowed primary and secondary radical precursors, including benzyl, allyl and alkylboron reagents, to be coupled in an enantio- and diastereocontrolled fashion. Cooperative photoredox-pyridoxal biocatalysis provides a platform for sp3-sp3 oxidative coupling16, permitting the stereoselective, intermolecular free-radical transformations that are unknown to chemistry or biology.

Facile fabrication of adenosine triphosphate/chitosan/polyethyleneimine coating for high flame-retardant lyocell fabrics with outstanding antibacteria.

Addressing highly flammable and easily breeding bacteria property via environmentally friendly approach was critical for the large-scale application of lyocell fibers. Herein, a bio-based coating constructed by layer-by-layer deposition of adenosine triphosphate (ATP), chitosan (CS), and polyethyleneimine (PEI) was successfully fabricated to obtain excellent fire-resistant and antimicrobial lyocell fabrics (LBL/Lyocell). The resulted fabrics with add-on of 11.5 wt% achieved the limiting oxygen index (LOI) of 32.0 %. Meanwhile, compared with the pure lyocell fabrics, the peak of heat release rate (PHRR), total heat release (THR), and fire growth rate (FIGRA) of LBL/Lyocell fabrics decreased by 75.2 %, 61.0 % and 69.8 % in cone calorimetric test (CCT), respectively. By characterizing the gaseous products and solid residues, the presence of the ATP/CS/PEI coating could not only quickly form the dense expanded carbon layer by itself, but also promote the conversion of cellulose into thermal-stability residues, thus reducing the release of combustible substances during combustion and protecting the lyocell fabrics. In addition, LBL/Lyocell showed excellent antimicrobial properties with 99.99 % antibacterial rates against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). This bio-based coating was a promising candidate for efficiently flame-retardant cellulose fibers with excellent antibacteria.

Facile construction of bio-based high fire-safety cellulose fabrics with well wearing performance.

The design of flame-retardant cellulose fabrics suffered from deterioration on wearing performance and environmental issue. Here, we developed facile construction of bio-based high fire-safety cellulose fabrics (lyocell) that exploited the bio-based flame-retardant coating (APD) by adenosine triphosphate (ATP) and dicyandiamide (DCD) via ionic reaction. The rich phosphorus/nitrogen elements of APD enabled the excellent fire safety of APD/Lyocell. Specifically, the APD/Lyocell2 had a higher limiting oxygen index (LOI) value of 29.3 %, a lower peak of heat release rate (PHRR, decreasing by 66.6 %), and a reduced total heat rate (THR, lowered by 56.5 %) with respect to pure lyocell fabrics. Interestingly, the APD/Lyocell2 exhibited well flame-retardant durability via passing the vertical burning test after 100 rubs. The satisfactory flame-retardant behaviors of APD/Lyocell derived from the excellent synergistic effect on the gaseous-solid phases, where APD could release more non-flammable gasses and generate phosphoric acid, polyphosphoric acid, etc. to accelerate itself and cellulose dehydration into char residues during combustion. More importantly, the wearing performance of APD/Lyocell fabrics, such as handle, air permeability and tensile strength, etc. almost remained after treatment. The ease of operation and use of bio-based coating made it a promising option to obtain the practical lyocell fabrics with flame-retardancy.

Application of Tranexamic Acid in Shoulder Arthroscopic Surgery: A Randomised Controlled Trial.

Objective To explore the optimal administration route of tranexamic acid (TXA) in shoulder arthroscopic surgery. Methods Patients undergoing arthroscopic rotator cuff repair were randomly divided into four groups: control group (without TXA treatment), intravenous group (TXA was intravenously administered 10 minutes before surgery), irrigation group (TXA was added to the irrigation fluid during subacromial decompression and acromioplasty), and intravenous plus irrigation group (TXA was applied both intravenously and via intra-articular irrigation). The primary outcome was visual clarity assessed with visual analog scale (VAS) score, and the secondary outcomes included irrigation fluid consumption and time to subacromial decompression and acromioplasty procedure. Results There were 134 patients enrolled in the study, including 33 in the control group, 35 in the intravenous group, 32 in the irrigation group, and 34 in the intravenous plus irrigation group. The median and interquartile range of VAS scores for the intravenous, irrigation, and intravenous plus irrigation groups were 2.70 (2.50, 2.86) (Z = -3.677, P = 0.002), 2.67 (2.50, 2.77) (Z = -3.058, P < 0.001), and 2.91 (2.75, 3.00) (Z = -6.634, P < 0.001), respectively, significantly higher than that of the control group [2.44 (2.37, 2.53)]. Moreover, the control group consumed more irrigation fluid than the intravenous group, irrigation group, and intravenous plus irrigation group (all P < 0.05). The intravenous plus irrigation group consumed less irrigation fluid than either the intravenous group or the irrigation group (both P < 0.001). There was no difference in subacromial decompression and acromioplasty operative time among the four groups. Conclusion TXA applied both topically and systematically can improve intraoperative visual clarity, and the combined application is more effective.

Discovery of Novel Pyrazole-Based KDM5B Inhibitor TK-129 and Its Protective Effects on Myocardial Remodeling and Fibrosis.

Lysine-specific demethylase 5B (KDM5B) has been recognized as a potential drug target for cardiovascular diseases. In this work, we first found that the KDM5B level was increased in mouse hearts after transverse aortic constriction (TAC) and in Ang II-induced activated cardiac fibroblasts. Structure-based design and further optimizations led to the discovery of highly potent pyrazole-based KDM5B inhibitor TK-129 (IC50 = 0.044 µM). TK-129 reduced Ang II-induced activation of cardiac fibroblasts in vitro, exhibited good PK profile (F = 42.37%), and reduced isoprenaline-induced myocardial remodeling and fibrosis in vivo. Mechanistically, we found that KDM5B up-regulation in cardiac fibroblast activation was associated with the activation of Wnt-related pathway. The protective effects of TK-129 were associated with its KDM5B inhibition and blocking KDM5B-related Wnt pathway activation. Taken together, TK-129 may represent a novel KDM5-targeting lead compound for cardiac remodeling and fibrosis.

Lactoferrin Prevents Chronic Alcoholic Injury by Regulating Redox Balance and Lipid Metabolism in Female C57BL/6J Mice.

This study aimed to investigate the preventive effects of lactoferrin (Lf) on chronic alcoholic liver injury (ALI) in female mice. Female C57BL/6J mice were randomly divided into four groups: control group (CON), ethanol administration group (EtOH), low-dose Lf treatment group (LLf), and high-dose Lf group (HLf). In the last three groups, chronic ALI was induced by administering 20% ethanol ad libitum for 12 weeks. Mice in the CON and EtOH groups were fed with AIN-93G diet. Meanwhile, 0.4% and 4% casein in the AIN-93G diet were replaced by Lf as the diets of LLf and HLf groups, respectively. HLf significantly reduced hepatic triglyceride content and improved pathological morphology. HLf could inhibit cytochrome P450 2E1 overexpression and promote alcohol dehydrogenase-1 expression. HLf activated protein kinase B and AMP-activated protein kinase (AMPK), as well as upregulating nuclear-factor-erythroid-2-related factor-2 expression to elevate hepatic antioxidative enzyme activities. AMPK activation also benefited hepatic lipid metabolism. Meanwhile, HLf had no obvious beneficial effects on gut microbiota. In summary, Lf could alleviate chronic ALI in female mice, which was associated with redox balance and lipid metabolism regulation.

Is replacing red meat with other protein sources associated with lower risks of coronary heart disease and all-cause mortality? A meta-analysis of prospective studies.

CONTEXT: A high amount of red meat consumption has been associated with higher risks of coronary heart disease (CHD) and all-cause mortality in a single food-exposure model. However, this model may overlook the potentially differential influence of red meat on these outcomes depending on the foods replaced by red meat. OBJECTIVE: A PRISMA-compliant meta-analysis of prospective observational studies was performed to quantify the risks of CHD and all-cause mortality associated with the replacement of total, unprocessed, or processed red meat with fish/seafood, poultry, dairy, eggs, nuts, and legumes. DATA SOURCES: The PubMed and Web of Science databases were searched to identify relevant articles published in any language from database inception to October 30, 2021. DATA EXTRACTION: The prospective observational studies were considered relevant if they reported relative risks (RRs) and 95%CIs for the associations of interest. DATA ANALYSIS: Thirteen articles were included. A random-effects model was used to estimate the summary RRs and 95%CIs for the associations of interest. Replacing total red meat with poultry (RR, 0.88, 95%CI, 0.82-0.96; I2 = 0%), dairy (RR, 0.90, 95%CI, 0.88-0.92; I2 = 0%), eggs (RR, 0.86, 95%CI, 0.79-0.94; I2 = 7.1%), nuts (RR, 0.84, 95%CI, 0.74-0.95; I2 = 66.8%), or legumes (RR, 0.84, 95%CI, 0.74-0.95; I2 = 7.3%) was associated with a lower risk of CHD, whereas substituting fish/seafood (RR, 0.91, 95%CI, 0.79-1.04; I2 = 69.5%) for total red meat was not associated with the risk of CHD. The replacement of total red meat with fish/seafood (RR, 0.92, 95%CI, 0.89-0.96; I2 = 86.9%), poultry (RR, 0.92, 95%CI, 0.90-0.95; I2 = 61.6%), eggs (RR, 0.91, 95%CI, 0.87-0.95; I2 = 33.8%), or nuts (RR, 0.92, 95%CI, 0.87-0.97; I2 = 81.9%) was associated with a lower risk of all-cause mortality, whereas the substitution of dairy (RR, 0.97, 95%CI, 0.93-1.01; I2 = 33.9%) or legumes (RR, 0.97, 95%CI, 0.93-1.01; I2 = 53.5%) for total red meat was not associated with the risk of all-cause mortality. Lower risks of CHD and all-cause mortality were more consistently observed for processed red meat replacements than for unprocessed red meat replacements. The results did not materially change when the analyses of total, processed, and unprocessed red meat were restricted to the studies that used a uniform substitution amount per unit of 1 serving/d. CONCLUSION: Keeping red meat, particularly processed red meat, consumption to a minimum along with increasing healthier alternative protein sources to replace red meat in the diet may contribute to the prevention of CHD and premature death. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration no. CRD42021259446.

The Effects of Milk Supplementation on Bone Health Indices in Adults: A Meta-Analysis of Randomized Controlled Trials.

Milk contains a number of bone-beneficial nutrients. However, milk, due to the D-galactose content, might have unfavorable effects on bone health. A meta-analysis of randomized controlled trials (RCTs) was performed to clarify the effects of milk supplementation on bone mineral density (BMD), bone turnover markers [N-terminal telopeptide of type I collagen (NTx), C-terminal telopeptide of type 1 collagen (CTx), osteocalcin, bone alkaline phosphatase (BALP), and procollagen type 1 N-propeptide (P1NP)], and hormonal indices related to bone metabolism [parathyroid hormone (PTH), 25-hydroxyvitamin D [25(OH)D], and insulin-like growth factor 1 (IGF-1)] in adults. The PubMed and Web of Science databases were searched. A random-effects model was used to estimate the pooled effect sizes. A total of 20 RCTs were included. The trial duration ranged from 1 mo to 36 mo. Milk supplementation resulted in a small but significant increase in BMD at the hip (+0.004 g/cm2; n = 9 RCTs) and lumbar spine (+0.025 g/cm2; n = 7), but did not significantly affect whole-body BMD (n = 3) and femoral neck BMD (n = 7). Milk supplementation reduced the concentrations of P1NP (-5.20 ng/mL; n = 9), CTx (-0.16 ng/mL; n = 9), and NTx (-8.66 nmol bone collagen equivalents/mmol creatinine; n = 3). The concentrations of osteocalcin (n = 9) and BALP (n = 3) were not affected by milk supplementation. Reduced parathyroid hormone PTH (-1.01 pg/mL; n = 13) concentrations and increased IGF-1 (+1.79 nmol/l; n = 4) concentrations were observed with milk supplementation. 25(OH)D (+3.73 ng/mL; n = 11) concentrations were increased with vitamin-D fortified milk supplementation. The addition of milk to the diet may potentially increase the likelihood of preventing bone loss by restoring bone homeostasis through the modulation of the calcium-vitamin D-PTH axis, bone remodeling rate, and growth hormone/IGF-1 axis.

Palladium-Catalyzed Enantioselective C(sp3)-H/C(sp3)-H Umpolung Coupling of N-Allylimine and α-Aryl Ketones.

Asymmetric functionalization of the C(sp3)-H bond is an attractive yet challenging strategy to achieve versatile bond-forming events, enabling the precise assembly of molecular complexity with minimal manipulation of functional groups. Here, we report an asymmetric C(sp3)-H/C(sp3)-H umpolung coupling of N-allylimine and coordinating α-aryl carbonyls by using chiral phosphoramidite-palladium catalysis. A wide variety of α-heteroaryl ketones and 2-acylimidazoles are nicely tolerated to open a convenient and tunable avenue for efficient synthesis of enantioenriched ß-amino-γ,δ-unsaturated carbonyl derivatives with high levels of regio- and stereoselectivities, capable of providing a key intermediate for asymmetric synthesis of Focalin. This protocol showcases an umpolung reactivity of the N-allylimines through a concerted proton and two-electron transfer process to cleave the allylic C-H bond, effectively complementing established methodology for allylic C-H functionalization. An inner-sphere allylation pathway for both α-heteroaryl carbonyls and 2-acylimidazoles to attack the π-allylpalladium species is suggested by computational studies and experimental facts, wherein the nitrogen coordination to the palladium center enables the preference of branched regioselectivity.

Treatment of posterolateral tibial plateau fractures with a rotational support plate and special pressurizer: technical note and retrospective case series.

BACKGROUND: In tibial plateau fractures, the posterolateral segment of the tibia plateau is frequently affected and challenging to treat. Although there are many surgical approaches and fixation methods for the treatment of these fractures, all of these methods have limitations. We designed a new rotational support plate (RSP) and a special pressurizer that can fix the fracture directly via the anterolateral approach. This method is advantageous because it leads to little trauma, involves a simple operation, and has a reliable fixation effect. This study details the technique of treating these fractures with the RSP and special pressurizer and provides the outcomes. METHODS: From May 2016 to January 2019, the data of 12 patients with posterolateral tibial plateau fractures treated with the RSP and special pressurizer in our hospital were retrospectively analyzed. Postoperative rehabilitation was advised, knee X-rays were taken at follow-ups, and fracture healing, complications, and knee range of motion were assessed. The Hospital for Special Surgery (HSS) knee score and Knee Injury and Osteoarthritis Outcome Score (KOOS) were used to evaluate knee function at the last follow-up. RESULTS: The average follow-up time of all patients was 16.5 months (range, 12-25 months). The average bony union time was 3.2 months (range, 3-4.5 months). At the last follow-up, the average knee range of motion was 138° (range, 107-145°). The average HSS score was 91 (range, 64-98). The average KOOS Symptoms score was 90 (range, 75-96). The average KOOS Pain score was 91 (range, 72-97). The average KOOS ADL score was 91 (range, 74-97). The average KOOS sport/recreation score was 83 (range, 70-90). The average KOOS QOL score was 88 (range, 69-93). Skin necrosis, incision infections, and fixation failure did not occur during the follow-up period. CONCLUSIONS: With our newly designed RSP and special pressurizer, posterolateral tibial plateau fractures can be easily and effectively reduced and fixed through the anterolateral approach, which serves as a novel treatment for posterolateral tibial plateau fractures.

Nucleophile Coordination Enabled Regioselectivity in Palladium-Catalyzed Asymmetric Allylic C-H Alkylation.

Branched selectivity in asymmetric allylic C-H alkylation is enabled by using 2-acylimidazoles as nucleophiles in the presence of a chiral phosphoramidite-palladium catalyst. A wide range of terminal alkenes, including 1,4-dienes and allylarenes, are nicely tolerated and provide chiral 2-acylimidazoles in moderate to high yields and with high levels of regio-, and enantio-, and E/Z-selectivities. Mechanistic studies using density-functional theory calculations suggest a nucleophile-coordination-enabled inner-sphere attack mode for the enantioselective carbon-carbon bond-forming event.

Asymmetric Allylic C-H Alkylation of Allyl Ethers with 2-Acylimidazoles.

An asymmetric allylic C-H alkylation of allyl ethers has been established by chiral phosphoramidite-palladium catalysis, affording a wide variety of functionalized chiral 2-acylimidazoles in moderate to high yields and with high levels of enantioselectivity. Moreover, this protocol could be applied to a concise asymmetric synthesis of a tachykinin receptor antagonist.

Nucleophile-Dependent Z/ E- and Regioselectivity in the Palladium-Catalyzed Asymmetric Allylic C-H Alkylation of 1,4-Dienes.

The asymmetric allylic alkylation (AAA), which features employing active allylic substrates, has historical significance in organic synthesis. The allylic C-H alkylation is principally more atom- and step-economic than the classical allylic functionalizations and thus can be considered a transformative variant. However, asymmetric allylic C-H alkylation reactions are still scarce and yet underdeveloped. Herein, we have found that Z/ E- and regioselectivities in the Pd-catalyzed asymmetric allylic C-H alkylation of 1,4-dienes are highly dependent on the type of nucleophiles. A highly stereoselective allylic C-H alkylation of 1,4-dienes with azlactones has been established by palladium-chiral phosphoramidite catalysis. The protocol proceeds under mild conditions and can accommodate a wide scope of substrates, delivering structurally divergent α,α-disubstituted α-amino acid surrogates in high yields and excellent levels of diastereo-, Z/ E-, regio-, and enantioselectivities. Notably, this method provides key chiral intermediates for an efficient synthesis of lepadiformine marine alkaloids. Experimental and computational studies on the reaction mechanism suggest a novel concerted proton and two-electron transfer process for the allylic C-H cleavage and reveal that the Z/ E- and regioselectivities are governed by the geometry and coordination pattern of nucleophiles.

Correction to: Nitric Oxide Participates in the Brain Ischemic Tolerance Induced by Intermittent Hypobaric Hypoxia in the Hippocampal CA1 Subfield in Rats.

The order of corresponding author was inadvertently published. Hence, the first and the second corresponding authors should be Min Zhang (hebmuzhangmin@163.com) and Jing-Ge Zhang (zhangjg001@163.com).

Enantioselective Synthesis of 5-Alkylated Thiazolidinones via Palladium-Catalyzed Asymmetric Allylic C-H Alkylations of 1,4-Pentadienes with 5 H-Thiazol-4-ones.

A palladium-catalyzed, enantioselective allylic C-H alkylation of 1,4-pentadienes with 5 H-thiazol-4-ones has been developed. Under the cooperative catalysis of a palladium complex of chiral phosphoramidite ligand and an achiral Brønsted acid, a broad range of substituted 5 H-thiazol-4-ones bearing sulfur-containing tertiary chiral centers were accessed from the allylic C-H alkylation in high levels of yields and enantioselectivities. Alkyl and aryl 1,4-pentadienes led to linear and branched allylation products, respectively.

Nitric Oxide Participates in the Brain Ischemic Tolerance Induced by Intermittent Hypobaric Hypoxia in the Hippocampal CA1 Subfield in Rats.

Previous studies have shown that intermittent hypobaric hypoxia (IH) preconditioning protected neurons survival from brain ischemia. However, the mechanism remains to be elucidated. The present study explored the role of nitric oxide (NO) in the process by measuring the expression of NO synthase (NOS) and NO levels. Male Wistar rats (100) were randomly assigned into four groups: sham group, IH + sham group, ischemia group and IH + ischemia group. Rats for IH preconditioning were exposed to hypobaric hypoxia mimicking 5000 m high-altitude (PB = 404 mmHg, PO2 = 84 mmHg) 6 h/day, once daily for 28 days. Global brain ischemia was established by four-vessel occlusion that has been created by Pulsinelli. Rats were sacrificed at 7th day after the ischemia for neuropathological evaluation by thionin stain. In addition, the expression of neuronal NOS (nNOS), inducible NOS (iNOS), and NO content in the hippocampal CA1 subfield were measured at 2nd day and 7th day after the ischemia. Results revealed that global brain ischemia engendered delayed neuronal death (DND), both nNOS and iNOS expression up-regulated, and NO content increased in the hippocampal CA1 subfield. IH preconditioning reduced neuronal injury induced by the ischemia, and prevented the up-regulation of NOS expression and NO production. In addition, L-NAME + ischemia group was designed to detect whether depressing NO production could alleviate the DND. Pre-administration of L-NAME alleviated DND induced by the ischemia. These results suggest that IH preconditioning plays a protective role by inhibiting the over expression of NOS and NO content after brain ischemia.

Access to Chiral Hydropyrimidines through Palladium-Catalyzed Asymmetric Allylic C-H Amination.

A palladium-catalyzed asymmetric intramolecular allylic C-H amination controlled by a chiral phosphoramidite ligand was established for the preparation of various substituted chiral hydropyrimidinones, the precursors of hydropyrimidines, in high yields with high enantioselectivities. In particular, dienyl sodium N-sulfonyl amides bearing an arylethene-1-sulfonyl group underwent a sequential allylic C-H amination and intramolecular Diels-Alder (IMDA) reaction to produce chiral fused tricyclic tetrahydropyrimidinone frameworks in high yields and with high levels of stereoselectivity. Significantly, this method was used as the key step in an asymmetric synthesis of letermovir.