Switchable Synthesis of Spirodihydroindolizines and Indolizines from Aurones and Pyridin-2-yl Active Methylene Compounds.

A novel and flexible domino reaction of aurones with pyridin-2-yl active methylene compounds promoted by I2/BF3 has been developed to afford spirodihydroindolizines and indolizines in a controllable manner. When the reaction was performed in 1,2-dichloroethane at 80 °C, a variety of spirodihydroindolizines were obtained, whereas it almost exclusively provided a series of indolizines when the reaction was performed in a mixed solvent of 1,2-dichloroethane and N,N-dimethylformamide at a relatively higher temperature of 100 °C. Being metal-free, excellent product selectivity, high atom economy, good functional group tolerance, and feasibility for large-scale synthesis are the salient features of the developed methodology.

Predictive model for epileptogenic tubers from all tubers in patients with tuberous sclerosis complex based on 18F-FDG PET: an 8-year single-centre study.

BACKGROUND: More than half of patients with tuberous sclerosis complex (TSC) suffer from drug-resistant epilepsy (DRE), and resection surgery is the most effective way to control intractable epilepsy. Precise preoperative localization of epileptogenic tubers among all cortical tubers determines the surgical outcomes and patient prognosis. Models for preoperatively predicting epileptogenic tubers using 18F-FDG PET images are still lacking, however. We developed noninvasive predictive models for clinicians to predict the epileptogenic tubers and the outcome (seizure freedom or no seizure freedom) of cortical tubers based on 18F-FDG PET images. METHODS: Forty-three consecutive TSC patients with DRE were enrolled, and 235 cortical tubers were selected as the training set. Quantitative indices of cortical tubers on 18F-FDG PET were extracted, and logistic regression analysis was performed to select those with the most important predictive capacity. Machine learning models, including logistic regression (LR), linear discriminant analysis (LDA), and artificial neural network (ANN) models, were established based on the selected predictive indices to identify epileptogenic tubers from multiple cortical tubers. A discriminating nomogram was constructed and found to be clinically practical according to decision curve analysis (DCA) and clinical impact curve (CIC). Furthermore, testing sets were created based on new PET images of 32 tubers from 7 patients, and follow-up outcome data from the cortical tubers were collected 1, 3, and 5 years after the operation to verify the reliability of the predictive model. The predictive performance was determined by using receiver operating characteristic (ROC) analysis. RESULTS: PET quantitative indices including SUVmean, SUVmax, volume, total lesion glycolysis (TLG), third quartile, upper adjacent and standard added metabolism activity (SAM) were associated with the epileptogenic tubers. The SUVmean, SUVmax, volume and TLG values were different between epileptogenic and non-epileptogenic tubers and were associated with the clinical characteristics of epileptogenic tubers. The LR model achieved the better performance in predicting epileptogenic tubers (AUC = 0.7706; 95% CI 0.70-0.83) than the LDA (AUC = 0.7506; 95% CI 0.68-0.82) and ANN models (AUC = 0.7425; 95% CI 0.67-0.82) and also demonstrated good calibration (Hosmer‒Lemeshow goodness-of-fit p value = 0.7). In addition, DCA and CIC confirmed the clinical utility of the nomogram constructed to predict epileptogenic tubers based on quantitative indices. Intriguingly, the LR model exhibited good performance in predicting epileptogenic tubers in the testing set (AUC = 0.8502; 95% CI 0.71-0.99) and the long-term outcomes of cortical tubers (1-year outcomes: AUC = 0.7805, 95% CI 0.71-0.85; 3-year outcomes: AUC = 0.8066, 95% CI 0.74-0.87; 5-year outcomes: AUC = 0.8172, 95% CI 0.75-0.87). CONCLUSIONS: The 18F-FDG PET image-based LR model can be used to noninvasively identify epileptogenic tubers and predict the long-term outcomes of cortical tubers in TSC patients.

Tyrosine phosphorylation of band 3 impairs the storage quality of suspended red blood cells in the Tibetan high-altitude polycythemia population.

Due to environmental hypoxia on the Tibetan Plateau, local residents often exhibit a compensative increase in hemoglobin concentration to maintain the body's oxygen supply. However, increases in hemoglobin and hematocrit (Hct) pose a serious challenge to the quality of stored suspended red blood cells (SRBCs) prepared from the blood of high-hemoglobin populations, especially populations at high altitude with polycythemia in Tibet. To explore the difference in storage quality of SRBCs prepared from plateau residents with a high hemoglobin concentration, blood donors were recruited from Tibet (> 3600 m) and Chengdu (≈ 500 m) and divided into a high-altitude control (HAC) group, high-altitude polycythemia (HAPC) group and lowland control (LLC) group according to their hemoglobin concentration and altitude of residence. The extracellular acidification rate (ECAR), pyruvate kinase (PK) activity and band 3 tyrosine phosphorylation were analyzed on the day of blood collection. Then, whole-blood samples were processed into SRBCs, and storage quality parameters were analyzed aseptically on days 1, 14, 21 and 35 of storage. Overall, we found that tyrosine 21 phosphorylation activated glycolysis by releasing glycolytic enzymes from the cytosolic domain of band 3, thus increasing glucose consumption and lactate accumulation during storage, in the HAPC group. In addition, band 3 tyrosine phosphorylation impaired erythrocyte deformability, accompanied by the highest hemolysis rate in the HAPC group, during storage. We believe that these results will stimulate new ideas to further optimize current additive solutions for the high-hemoglobin population in Tibet and reveal new therapeutic targets for the treatment of HAPC populations.

Aerobic CuBr2-Catalyzed Oxidative Coupling Reaction of Amidines with Exocyclic α,ß-Unsaturated Cycloketones for the Synthesis of Spiroimidazolines.

A CuBr2-catalyzed cascade reaction of amidines with exocyclic α,ß-unsaturated cycloketones was developed, affording a large variety of spiroimidazolines in moderate to excellent yields. The reaction process involved the Michael addition and copper(II)-catalyzed aerobic oxidative coupling, in which O2 from air acted as the oxidant and H2O was the sole byproduct.

C(sp3)-H Aerobic Alkenylation of Tetrahydroisoquinolines via Organic Electrosynthesis.

A method for the C(sp3)-H alkenylation of N-aryl-tetrahydroisoquinoline (THIQ) has been developed by the combination of electrooxidation and a copper catalyst. The corresponding products were obtained with good to excellent yields under mild conditions. Besides, the addition of TEMPO as an electron mediator is crucial to this transformation, since the oxidative reaction could proceed under a low electrode potential. In addition, the catalytic asymmetric variant has also been demonstrated with good enantioselectivity.

Transcriptome analysis reveals molecular pathways in the iron-overloaded Tibetan population.

Iron overload can lead to chronic complications, serious organ dysfunction or death in the body. Under hypoxic conditions, the body needs more iron to produce red blood cells to adapt to the hypoxic environment. The prevalence of iron overload in the Tibetan population is higher than that in the Han population. To explore the molecular mechanism of iron-overload in the Tibetan population, this study investigated the transcriptome of the Tibetan iron overload population to obtain differentially expressed genes (DEGs) between the iron-overloaded population and the normal iron population. Functional enrichment analysis identified key related pathways, gene modules and coexpression networks under iron-overload conditions, and the 4 genes screened out have the potential to become target genes for studying the development of iron overload. A total of 28 pathways were screened to be closely related to the occurrence and development of iron overload, showing that iron overload is extremely related to erythrocyte homeostasis, cell cycle, oxidative phosphorylation, immunity, and transcriptional repression.

[Electroencephalogram Features of Anti-N-Methyl-D-Aspartate Receptor Encephalitis and Their Value for Clinical Assessment].

Objective: To analyze the electroencephalogram (EEG) features of anti-N-methyl-D-aspartate receptor encephalitis (anti-NMDARE) and to study the clinical assessment value of the degree of EEG background slowing and the presence of δ brush. Methods: We enrolled 52 patients with anti-NMDARE and collected their clinical data, including age, sex, form of disease onset, status of tumor comorbidity, auxiliary examination findings (cerebrospinal fluid [CSF] anti-methyl-D-aspartate receptor antibody titers, magnetic resonance imaging [MRI] reports, and EEG results), treatment status, and follow-up after discharge. The degree of EEG background abnormality and the presence of δ brush in the EEG of patients with different clinical features were analyzed. Results: Among the 52 patients, 7 (14%) had normal EEG, and 45 (87%), abnormal EEG, including 25 (48%) with mild abnormalities, 11 (21%) with moderate abnormalities, and 9 (17%) with severe abnormalities. δ brush was seen in 6 (12%) patients. At the time of EEG, 32 (62%) patients were in the mild condition group and 20 (38%) patients were in the severe condition group. After 1 year of follow-up, there were 45 (86%) patients in the good prognosis group and 7 (14%) patients in the poor prognosis group. The exacerbation of EEG background abnormalities and the presence of δ brush were indications for an increase in the proportion of patients who were in severe condition, who needed ICU admission, and who had poor prognosis ( P<0.01). The worse the EEG background abnormalities, the higher the proportion of CSF antibody titers>1∶10 ( P=0.035), and the higher the proportion of patients initiating second-line immunotherapy ( P=0.008). The δ brush was seen a higher proportion in patients with comorbid tumors ( P=0.012). The probability of δ brush presence was higher in the first-time diagnosis cases than that in recurrent cases ( P=0.023). Conclusions: The degree of EEG slowing and the presence of δ brush have shown consistent performance in assessing patients' condition and predicting prognosis. The slower the EEG, the more severe the disease, and the worse the prognosis. The presence of δ brush indicates severe disease and poor prognosis. EEG slowing is correlated with the immune status of patients with anti-NMDARE. The slower the EEG, the more severe the immune abnormalities. In clinical practice, patient EEG should be under dynamic monitoring in order to evaluate the effect of immunotherapy. If EEG slowing is not improved, enhanced immunotherapy should be considered as early as possible. The δ brush is seen at a higher proportion in patients with comorbid tumors. Therefore, active efforts should be made to screen for tumors when δ brush is present.

TEMPO-Enabled Electrochemical Enantioselective Oxidative Coupling of Secondary Acyclic Amines with Ketones.

An electrochemical asymmetric coupling of secondary acyclic amines with ketones via a Shono-type oxidation has been described, affording the corresponding amino acid derivatives with good to excellent diastereoselectivity and enantioselectivity. The addition of an N-oxyl radical as a redox mediator could selectively oxidize the substrate rather than the product, although their oxidation potential difference is subtle (about 13 mV). This electrochemical transformation proceeds in the absence of stoichiometric additives, including metals, oxidants, and electrolytes, which gives it good functional group compatibility. Mechanistic studies suggest that proton-mediated racemization of the product is prevented by the reduction of protons at the cathode.

Application of machine learning models for predicting acute kidney injury following donation after cardiac death liver transplantation.

BACKGROUND: Acute kidney injury (AKI) is a common complication after liver transplantation (LT) and is an indicator of poor prognosis. The establishment of a more accurate preoperative prediction model of AKI could help to improve the prognosis of LT. Machine learning algorithms provide a potentially effective approach. METHODS: A total of 493 patients with donation after cardiac death LT (DCDLT) were enrolled. AKI was defined according to the clinical practice guidelines of kidney disease: improving global outcomes (KDIGO). The clinical data of patients with AKI (AKI group) and without AKI (non-AKI group) were compared. With logistic regression analysis as a conventional model, four predictive machine learning models were developed using the following algorithms: random forest, support vector machine, classical decision tree, and conditional inference tree. The predictive power of these models was then evaluated using the area under the receiver operating characteristic curve (AUC). RESULTS: The incidence of AKI was 35.7% (176/493) during the follow-up period. Compared with the non-AKI group, the AKI group showed a remarkably lower survival rate (P < 0.001). The random forest model demonstrated the highest prediction accuracy of 0.79 with AUC of 0.850 [95% confidence interval (CI): 0.794-0.905], which was significantly higher than the AUCs of the other machine learning algorithms and logistic regression models (P < 0.001). CONCLUSIONS: The random forest model based on machine learning algorithms for predicting AKI occurring after DCDLT demonstrated stronger predictive power than other models in our study. This suggests that machine learning methods may provide feasible tools for forecasting AKI after DCDLT.

An Evaluation of Morphological Changes and Deformability of Suspended Red Blood Cells Prepared Using Whole Blood with Different Hemoglobin Levels of Tibetans.

BACKGROUND: The hypoxic environment stimulates the human body to increase the levels of hemoglobin (HGB) and hematocrit and the number of red blood cells. Such enhancements have individual differences, leading to a wide range of HGB in Tibetans' whole blood (WB). STUDY DESIGN: WB of male Tibetans was divided into 3 groups according to different HGB (i.e., A: >120 but ≤185 g/L, B: >185 but ≤210 g/L, and C: >210 g/L). Suspended red blood cells (SRBC) processed by collected WB and stored in standard conditions were examined aseptically on days 1, 14, 21, and 35 after storage. The routine biochemical indexes, deformability, cell morphology, and membrane proteins were tested. RESULTS: Mean corpuscular volume, adenosine triphosphate, pH, and deformability were not different in group A vs. those in storage (p > 0.05). The increased rate of irreversible morphology of red blood cells was different among the 3 groups, but there was no difference in the percentage of red blood cells with an irreversible morphology after 35 days of storage. Group C performed better in terms of osmotic fragility and showed a lower rigid index than group A. Furthermore, SDS-PAGE revealed similar cross-linking degrees of cell membrane protein but the band 3 protein of group C seemed to experience weaker clustering than that of group A as detected by Western Blot analysis after 35 days of storage. CONCLUSIONS: There was no difference in deformability or morphological changes in the 3 groups over the 35 days of storage. High HGB levels of plateau SRBC did not accelerate the RBC change from a biconcave disc into a spherical shape and it did not cause a reduction in deformability during 35 days of preservation in bank conditions.

Silencing of microRNA-375 affects immune function in mice with liver failure by upregulating astrocyte elevated gene-1 through reducing apoptosis of Kupffer cells.

This study aims to investigate how microRNA-375 (miR-375) improves immune function by regulating liver macrophages (Kupffer cells) in mice with liver failure. Forty mice were divided into ConA-1h, ConA-3h, ConA-6h, and control groups, with 10 mice in each group. Mice models of liver failure were established by injecting concanavalin A (ConA) solution via the tail veins of mice, and then primary Kupffer cells were isolated and cultured. Reverse transcription quantitative polymerase chain reaction, Western blot analysis, and enzyme-linked immunosorbent assay were conducted to examine the expressions of miR-375, astrocyte elevated gene-1 (AEG-1), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and IL-1ß in Kupffer cells of mice with liver failure as well as after silencing of miR-375. Flow cytometry was used to determine cell apoptosis. During the liver failure process, miR-375, IL-6, TNF-α, and IL-1ß expressions were increased over time, while AEG-1 expression decreased over time in the control, ConA-1h, ConA-3h, and ConA-6h groups. Opposite alternations were observed after silencing of miR-375. Dual-luciferase reporter gene assay showed that AEG-1 was a target gene of miR-375. Flow cytometry determination showed that the ratio of apoptotic Kupffer cells decreased after silencing of miR-375. Overexpression of AEG-1 could rescue the suppression of IL-6, TNF-α, and IL-1ß expressions in Kupffer cells after the short-term induction of ConA and further inhibit cell apoptosis. Our study provides evidence that miR-375 could regulate Kupffer cells to improve immune function in mice with liver failure.

The removal of Rhodamine B by H2O2 or ClO2 combined with hydrodynamic cavitation.

Rhodamine B (RhB), widely used as an industrial dye, is a toxic organic that is hazardous to human health and can cause water pollution. In this study, the removal rate of RhB was investigated by the following methods: hydrodynamic cavitation (HC) operated individually, and HC combined with oxidants H2O2 or ClO2. The effect of different operating parameters including pressure (2-6 bar) and initial pH (2-8) on the extent of degradation was investigated using an orifice plate as the cavitation device to achieve maximum removal of RhB. Under the parameters of HC, the effect of different loadings was investigated: H2O2 (n(RhB):n(H2O2) was varied from 1:17.60 to 1:211.28) and ClO2 (n(RhB):n(ClO2) was varied from 1:8.87 to 1:177.53). A combination of cavitation and H2O2 or ClO2 resulted in degradations of 80.6% and 95.3%. The results indicated that the combination of HC and oxidants was better than the individual HC process for the degradation of RhB. When combining HC with H2O2 or ClO2, the synergistic coefficients of 62.54 and 74.79 were obtained. The combination of HC and ClO2 was proven to be more effective for the removal of RhB compared to HC alone and the hybrid process of HC and H2O2.

[Research progress on Chinese herbal medicine fermentation and profile of active substances derived].

Chinese herbal medicines( CHMs) are a class of preparations made from natural plants that pose health beneficial properties as well as illness prevention functions. Thanks to a panel of salutary features,such as comprehensive immunological enhancement and inhibition of pathogenic bacteria,negligible side-effects,inappreciable drug-resistance,CHMs have been taken as one of the costeffective candidates for antibiotics substitutions. Through probiotics fermentation,the enzymatic hydrolysis of matrixes of CHMs enables easier release of the active ingredient as well as endows less toxicity of the preparations derived. During fermentation,the macromolecule or polymers forms of the active ingredient can be cut down to smaller molecule,which favors the transmembrane transport and improve adsorption of the active ingredients by the tissues. Other than the enzymatic benefits,probiotics can produce metabolites that inhibit pathogenic bacteria propagation,which may function synergically with the inhibitory effects of the CHMs preparations to fight the target pathogens. In addition,the oligosaccharide like components of CHMs can promote the growth of probiotics in intestinal environment which may largely facilitate the gut health. To summarize,the fermentation of CHMs using probiotics brings about the biochemical reactions and elevates the health beneficial effects by synergy of the microbial and herbal activities. It has been proved to be one of promising approaches as to antibiotic substitutions,particularly in livestock and poultry breeding industries. This review covered the recent progress of CHMs fermentation on the aspects of microbial strains,patterns of fermentation and active substances from fermentation of CHMs and their potency,respectively.

Kinetic Resolution of Racemic Allylic Alcohols by Catalytic Asymmetric Substitution of the OH Group with Monosubstituted Hydrazines.

A new strategy has been established for the kinetic resolution of racemic allylic alcohols through a palladium/sulfonyl-hydrazide-catalyzed asymmetric OH-substitution under mild conditions. In the presence of 1 mol % [Pd(allyl)Cl]2 , 4 mol % (S)-SegPhos, and 10 mol % 2,5-dichlorobenzenesulfonyl hydrazide, a range of racemic allylic alcohols were smoothly resolved with selectivity factors of more than 400 through an asymmetric allylic alkylation of monosubstituted hydrazines under air at room temperature. Importantly, this kinetic resolution process provided various allylic alcohols and allylic hydrazine derivatives with high enantiopurity.

Palladium/copper-catalyzed oxidative arylation of terminal alkenes with aroyl hydrazides.

An unprecedented oxidative arylation reaction of terminal alkenes with simple aroyl hydrazides has been developed under aerobic conditions for the stereoselective synthesis of 1,2-disubstituted alkenes. A range of aroyl hydrazides underwent palladium/copper-catalyzed oxidative Mizoroki-Heck reaction with terminal alkenes open to air in a 1:1 mixture of dimethyl sulfoxide and acetonitrile to give structurally diverse 1,2-disubstituted alkenes in moderate to excellent yields with excellent regio- and E-selectivity. The reaction tolerated a wide variety of functional groups, such as alkoxy, hydroxy, amino, fluoro, chloro, bromo, cyano, nitro, ester, amide, imide, phosphine oxide, and sulfone groups, and, moreover, molecular oxygen and dimethyl sulfoxide were demonstrated to serve as terminal oxidants. This study provides a useful method for the stereoselective synthesis of 1,2-disubstituted alkenes through direct transformation of the vinylic CH bonds in terminal alkenes.

Impact of high-altitude acclimatization and de-acclimatization on the intestinal microbiota of rats in a natural high-altitude environment.

Introduction: Intestinal microorganisms play an important role in the health of both humans and animals, with their composition being influenced by changes in the host's environment. Methods: We evaluated the longitudinal changes in the fecal microbial community of rats at different altitudes across various time points. Rats were airlifted to high altitude (3,650 m) and acclimatized for 42 days (HAC), before being by airlifted back to low altitude (500 m) and de-acclimatized for 28 days (HADA); meanwhile, the control group included rats living at low altitude (500 m; LA). We investigated changes in the gut microbiota at 12 time points during high-altitude acclimatization and de-acclimatization, employing 16S rRNA gene sequencing technology alongside physiological indices, such as weight and daily autonomous activity time. Results: A significant increase in the Chao1 index was observed on day 14 in the HAC and HADA groups compared to that in the LA group, indicating clear differences in species richness. Moreover, the principal coordinate analysis revealed that the bacterial community structures of HAC and HADA differed from those in LA. Long-term high-altitude acclimatization and de- acclimatization resulted in the reduced abundance of the probiotic Lactobacillus. Altitude and age significantly influenced intestinal microbiota composition, with changes in ambient oxygen content and atmospheric partial pressure being considered key causal factors of altitude-dependent alterations in microbiota composition. High-altitude may be linked to an increase in anaerobic bacterial abundance and a decrease in non-anaerobic bacterial abundance. Discussion: In this study, the hypobaric hypoxic conditions at high-altitude increased the abundance of anaerobes, while reducing the abundance of probiotics; these changes in bacterial community structure may, ultimately, affect host health. Overall, gaining a comprehensive understanding of the intestinal microbiota alterations during high-altitude acclimatization and de-acclimatization is essential for the development of effective prevention and treatment strategies to better protect the health of individuals traveling between high- and low-altitude areas.

In vitro investigation of the effect of plasticizers on the blood compatibility of medical grade plasticized poly (vinyl chloride).

This paper reports the results of an in vitro investigation into the blood response of medical grade poly (vinyl chloride) (PVC), and two types of plasticized PVC in tubing or sheet form, with di-(2-ethylhexyl)phthalate (DEHP) and di(isononyl) cyclohexane-1,2-dicarboxylate (HEXAMOLL(®) DINCH) as plasticizer, were selected for assessment of complement activation, coagulation system and platelet activation. The results of the study show that not only the plasticizers at PVC surface have an influence on complement activation, but also the incubation condition such as incubation time and the diameter of PVC tubing. Under static status, C3a, C5a and SC5b-9 concentration in the blood were higher after contacting with PVC plasticized with DEHP (PVC1) than after contacting with PVC plasticized with DINCH (PVC2). However, under dynamic circulation, the results were totally converse, which may be due to smaller diameter and higher shear rate of PVC2. In addition, there was a significant increase of activated partial thrombin time (APTT) and decrease of FIX concentration after plasma contacting with the PVC tubing, which indicated that the intrinsic pathway may be impacted when blood contacted with PVC tubing. However, there was no significant difference of APTT, FIX concentration and CD62p expression rate between the two materials. Moreover, the migration in the DINCH system was considerably lower than for DEHP, which indicates that DINCH could be a promising alterative plasticizer of DEHP.

[Seminal parameters at different times of reanalysis of the normal semen samples detected in initial examination and their correlation with sperm DNA damage].

OBJECTIVE: To investigate the differences in semen quality at different times of reanalysis and the correlation of sperm DNA fragmentation index (DFI) with sperm motility alteration using semen samples completely liquefied and normal in initial examination. METHODS: We analyzed 127 semen samples up to the inclusion criteria with the computer-assisted semen analysis (CASA) system at 15, 30 and 60 min after semen collection, and obtained sperm morphology parameters and DFI by Shorr staining and acridine orange test (AOT) , respectively. RESULTS: Sperm concentration, and the percentages of grades a and b sperm showed no statistically significant differences at the three time points (P > 0.05). The percentages of grades a + b and a + b + c sperm were significantly higher at 15 min than at 30 and 60 min after semen collection (P < 0.05), but with no significant difference between the latter two time points (P > 0.05). The incidence of alternation from normal to abnormal in at least one index of sperm motility at different times was 25.2%, but there were no significant differences in sperm DFI and morphology between the normal and abnormal groups (P > 0.05). Among the altered parameters of sperm motility from 15 to 60 min, the percentages of grades a, a + b and a + b + c sperm were all positively correlated with sperm DFI (P < 0.05). CONCLUSION: Semen samples completely liquefied within 15 min after collection and normal in initial examination, when reanalyzed at 30 and 60 min, showed significant decreases in the percentages of grades a + b and a + b + c sperm, but not in the percentages of grades a and b sperm, and the parameters of sperm motility might be abnormal. Thus, at least 2 sperm analyses are required for a comprehensive evaluation of fertility. Significant difference between the results of the two analyses, and particularly a markedly reduced percentage of rapidly progressive sperm, might indicate sperm DNA damage, and thus the necessity of sperm DNA damage detection.

Polymerized human cord hemoglobin assisted with ascorbic acid as a red blood cell substitute alleviating oxidative stress for blood transfusion.

Introduction: Blood transfusion is widely used in clinical settings, where considerable efforts have been devoted to develop red blood cell substitutes to overcome blood shortage and safety concerns. Among the several kinds of artificial oxygen carriers, hemoglobin-based oxygen carriers are promising due to their inherent good oxygen-binding and -loading properties. However, difficulties in prone to oxidation, production of oxidative stress, and injury in organs limited their clinical utility. In this work, we report a red blood cell substitute composed of polymerized human cord hemoglobin (PolyCHb) assisted with ascorbic acid (AA) that alleviates oxidative stress for blood transfusion. Methods: In this study, the in vitro impacts of AA on the PolyCHb were evaluated by testing the circular dichroism, methemoglobin (MetHb) contents and oxygen binding affinity before and after the addition of AA. In the in vivo study, guinea pigs were subjected to a 50% exchange transfusion with PolyCHb and AA co-administration, followed by the collection of blood, urine, and kidney samples. The hemoglobin contents of the urine samples were analyzed, and histopathologic changes, lipid peroxidation, DNA peroxidation, and heme catabolic markers in the kidneys were evaluated. Results: After treating with AA, there was no effect on the secondary structure and oxygen binding affinity of the PolyCHb, while the MetHb content was kept at 55%, which was much lower than that without AA treating. Moreover, the reduction of PolyCHbFe3+ was significantly promoted, and the content of MetHb could be reduced from 100% to 51% within 3 h. In vivo study results showed that PolyCHb assisted with AA inhibited the formation of hemoglobinuria, upgraded the total antioxidant capacity and downgraded the superoxide dismutase activity of kidney tissue, and lowered the expression of biomarkers for oxidative stress, e.g., malondialdehyde (ET vs ET+AA: 4.03±0.26 µmol/mg vs 1.83±0.16 µmol/mg), 4-hydroxy-2-nonenal (ET vs ET+AA: 0.98±0.07 vs 0.57±0.04), 8-hydroxy 2 deoxyguanosine(ET vs ET+AA: 14.81±1.58 ng/ml vs 10.91±1.36 ng/ml), heme oxygenase 1 (ET vs ET+AA: 1.51±0.08 vs 1.18±0.05) and ferritin (ET vs ET+AA: 1.75±0.09 vs 1.32±0.04). The kidney histopathology results also demonstrated that kidney tissue damage was effectively alleviated. Conclusion: In conclusion, these comprehensive results provide evidence for the potential role of AA in controlling oxidative stress and organ injury in the kidneys induced by PolyCHb, and suggest that PolyCHb assisted with AA has promising application for blood transfusion.

C(sp3)-H Alkenylation of Tetrahydroisoquinolines via Merging Electrochemistry and Organocatalysis.

C(sp3)-H alkenylation of tetrahydroisoquinoline by merging Shono oxidation and the Morita-Baylis-Hillman reaction is developed, employing 4-dimethylaminopyridine as an organocatalyst and TEMPO/NaBr as an electrocatalyst. The reaction proceeds via the interception of an iminium cation intermediate, which is generated in situ from anodic oxidation, leading to aza-Morita-Baylis-Hillman reaction products. Additionally, the use of TEMPO and NaBr as mediators is crucial to avoid the decomposition of products by lowering the oxidation potential of the reaction.