Nrf2 prevents diabetic cardiomyopathy via antioxidant effect and normalization of glucose and lipid metabolism in the heart.

Metabolic disorders and oxidative stress are the main causes of diabetic cardiomyopathy. Activation of nuclear factor erythroid 2-related factor 2 (Nrf2) exerts a powerful antioxidant effect and prevents the progression of diabetic cardiomyopathy. However, the mechanism of its cardiac protection and direct action on cardiomyocytes are not well understood. Here, we investigated in a cardiomyocyte-restricted Nrf2 transgenic mice (Nrf2-TG) the direct effect of Nrf2 on cardiomyocytes in DCM and its mechanism. In this study, cardiomyocyte-restricted Nrf2 transgenic mice (Nrf2-TG) were used to directly observe whether cardiomyocyte-specific overexpression of Nrf2 can prevent diabetic cardiomyopathy and correct glucose and lipid metabolism disorders in the heart. Compared to wild-type mice, Nrf2-TG mice showed resistance to diabetic cardiomyopathy in a streptozotocin-induced type 1 diabetes mouse model. This was primarily manifested as improved echocardiography results as well as reduced myocardial fibrosis, cardiac inflammation, and oxidative stress. These results showed that Nrf2 can directly act on cardiomyocytes to exert a cardioprotective role. Mechanistically, the cardioprotective effects of Nrf2 depend on its antioxidation activity, partially through improving glucose and lipid metabolism by directly targeting lipid metabolic pathway of AMPK/Sirt1/PGC-1α activation via upstream genes of sestrin2 and LKB1, and indirectly enabling AKT/GSK-3ß/HK-Ⅱ activity via AMPK mediated p70S6K inhibition.

Natural variation in the Tn1a promoter regulates tillering in rice.

Rice tillering is an important agronomic trait that influences plant architecture and ultimately affects yield. This can be genetically improved by mining favourable variations in genes associated with tillering. Based on a previous study on dynamic tiller number, we cloned the gene Tiller number 1a (Tn1a), which encodes a membrane-localised protein containing the C2 domain that negatively regulates tillering in rice. A 272 bp insertion/deletion at 387 bp upstream of the start codon in the Tn1a promoter confers a differential transcriptional response and results in a change in tiller number. Moreover, the TCP family transcription factors Tb2 and TCP21 repress the Tn1a promoter activity by binding to the TCP recognition site within the 272 bp indel. In addition, we identified that Tn1a may affect the intracellular K+ content by interacting with a cation-chloride cotransporter (OsCCC1), thereby affecting the expression of downstream tillering-related genes. The Tn1a+272 bp allele, associated with high tillering, might have been preferably preserved in rice varieties in potassium-poor regions during domestication. The discovery of Tn1a is of great significance for further elucidating the genetic basis of tillering characteristics in rice and provides a new and favourable allele for promoting the geographic adaptation of rice to soil potassium.

Upland rice genomic signatures of adaptation to drought resistance and navigation to molecular design breeding.

Upland rice is a distinctive drought-aerobic ecotype of cultivated rice highly resistant to drought stress. However, the genetic and genomic basis for the drought-aerobic adaptation of upland rice remains largely unclear due to the lack of genomic resources. In this study, we identified 25 typical upland rice accessions and assembled a high-quality genome of one of the typical upland rice varieties, IRAT109, comprising 384 Mb with a contig N50 of 19.6 Mb. Phylogenetic analysis revealed upland and lowland rice have distinct ecotype differentiation within the japonica subgroup. Comparative genomic analyses revealed that adaptive differentiation of lowland and upland rice is likely attributable to the natural variation of many genes in promoter regions, formation of specific genes in upland rice, and expansion of gene families. We revealed differentiated gene expression patterns in the leaves and roots of the two ecotypes and found that lignin synthesis mediated by the phenylpropane pathway plays an important role in the adaptive differentiation of upland and lowland rice. We identified 28 selective sweeps that occurred during domestication and validated that the qRT9 gene in selective regions can positively regulate drought resistance in rice. Eighty key genes closely associated with drought resistance were appraised for their appreciable potential in drought resistance breeding. Our study enhances the understanding of the adaptation of upland rice and provides a genome navigation map of drought resistance breeding, which will facilitate the breeding of drought-resistant rice and the "blue revolution" in agriculture.

Mechanism of the apoptosis of bone marrow erythroblasts in rats under hypobaric hypoxia.

This study aimed to investigate the mechanism of the apoptosis of erythroblasts in rat bone marrow after the exposure to hypobaric hypoxia. Male SD rats were randomly divided into three groups. The hypoxic group was kept in a hypobaric hypoxia chamber at a simulated altitude of 5000 m for 7 and 28 days, respectively. The control group was kept at an altitude of 2260 m. We found that myeloid: erythroid (M:E) ratio was significantly lower after hypoxia exposure and the proportions of polychromatic erythroblasts and orthochromatic erythroblasts significantly increased compared to control group, along with significant increase in the proportion of CD71+ cells and apoptosis rate. The expression levels of caspase-3, Bax, and Cyt-C in CD71+ cells were higher after hypoxia exposure than those in control group, while there was no significant difference in the expression levels of TNFR and Fas. In conclusion, after exposure to hypobaric hypoxia the proliferation of peripheral blood and bone marrow erythroblasts in rats increased, and apoptosis also increased, indicating that bone marrow erythroblasts in rats is regulated by both proliferation and apoptosis, and the mitochondrial pathway is one of the important pathways for apoptosis.

The wall-associated kinase GWN1 controls grain weight and grain number in rice.

Grain size is a crucial agronomic trait that determines grain weight and final yield. Although several genes have been reported to regulate grain size in rice (Oryza sativa), the function of Wall-Associated Kinase family genes affecting grain size is still largely unknown. In this study, we identified GRAIN WEIGHT AND NUMBER 1 (GWN1) using map-based cloning. GWN1 encodes the OsWAK74 protein kinase, which is conserved in plants. GWN1 negatively regulates grain length and weight by regulating cell proliferation in spikelet hulls. We also found that GWN1 negatively influenced grain number by influencing secondary branch numbers and finally increased plant grain yield. The GWN1 gene was highly expressed in inflorescences and its encoded protein is located at the cell membrane and cell wall. Moreover, we identified three haplotypes of GWN1 in the germplasm. GWN1hap1 showing longer grain, has not been widely utilized in modern rice varieties. In summary, GWN1 played a very important role in regulating grain length, weight and number, thereby exhibiting application potential in molecular breeding for longer grain and higher yield.

Copper metabolism and its role in diabetic complications: A review.

Disturbances in copper (Cu) homeostasis have been observed in diabetes and associated complications. Cu is an essential micronutrient that plays important roles in various fundamental biological processes. For example, diabetic cardiomyopathy is associated with elevated levels of Cu in the serum and tissues. Therefore, targeting Cu may be a novel treatment strategy for diabetic complications. This review provides an overview of physiological Cu metabolism and homeostasis, followed by a discussion of Cu metabolism disorders observed during the occurrence and progression of diabetic complications. Finally, we discuss the recent therapeutic advances in the use of Cu coordination complexes as treatments for diabetic complications and their potential mechanisms of action. This review contributes to a complete understanding of the role of Cu in diabetic complications and demonstrates the broad application prospects of Cu-coordinated compounds as potential therapeutic agents.

QTL detection and candidate gene identification of qCTB1 for cold tolerance in the Yunnan plateau landrace rice.

Cold stress is one of the main abiotic stresses that affects rice growth and production worldwide. Dissection of the genetic basis is important for genetic improvement of cold tolerance in rice. In this study, a new source of cold-tolerant accession from the Yunnan plateau, Lijiangxiaoheigu, was used as the donor parent and crossed with a cold-sensitive cultivar, Deyou17, to develop recombinant inbred lines (RILs) for quantitative trait locus (QTL) analysis for cold tolerance at the early seedling and booting stages in rice. In total, three QTLs for cold tolerance at the early seedling stage on chromosomes 2 and 7, and four QTLs at the booting stage on chromosomes 1, 3, 5, and 7, were identified. Haplotype and linear regression analyses showed that QTL pyramiding based on the additive effect of these favorable loci has good potential for cold tolerance breeding. Effect assessment in the RIL and BC3F3 populations demonstrated that qCTB1 had a stable effect on cold tolerance at the booting stage in the genetic segregation populations. Under different cold stress conditions, qCTB1 was fine-mapped to a 341-kb interval between markers M3 and M4. Through the combination of parental sequence comparison, candidate gene-based association analysis, and tissue and cold-induced expression analyses, eight important candidate genes for qCTB1 were identified. This study will provide genetic resources for molecular breeding and gene cloning to improve cold tolerance in rice. Supplementary Information: The online version contains supplementary material available at 10.1007/s11032-024-01488-3.

Downregulation of miR-337-3p in hypoxia/reoxygenation neuroblastoma cells increases KCTD11 expression.

Neurodegeneration is linked to the progressive loss of neural function and is associated with several diseases. Hypoxia is a hallmark in many of these diseases, and several therapies have been developed to treat this disease, including gene expression therapies that should be tightly controlled to avoid side effects. Cells experiencing hypoxia undergo a series of physiological responses that are induced by the activation of various transcription factors. Modulation of microRNA (miRNA) expression to alter transcriptional regulation has been demonstrated to be beneficial in treating multiple diseases, and in this study, we therefore explored potential miRNA candidates that could influence hypoxia-induced nerve cell death. Our data suggest that in mouse neuroblasts Neuro-2a cells with hypoxia/reoxygenation (H/R), miR-337-3p is downregulated to increase the expression of Potassium channel tetramerization domain containing 11 (KCTD11) and subsequently promote apoptosis. Here, we demonstrate for the first time that KCTD11 plays a role in the cellular response to hypoxia, and we also provide a possible regulatory mechanism by identifying the axis of miR-337-3p/KCTD11 as a promising candidate modulator of nerve cell survival after H/R exposure.

Effect of simethicone for the management of early abdominal distension after laparoscopic cholecystectomy: a multicenter retrospective propensity score matching study.

OBJECTIVE: To investigate whether simethicone expediates the remission of abdominal distension after laparoscopic cholecystectomy (LC). METHODS: This retrospective study involved LC patients who either received perioperative simethicone treatment or not. Propensity score matching (PSM) was employed to minimize bias. The primary endpoint was the remission rate of abdominal distension within 24 h after LC. Univariable and multivariable logistic regression analyses were conducted to identify independent risk factors affecting the early remission of abdominal distension after LC. Subsequently, a prediction model was established and validated. RESULTS: A total of 1,286 patients were divided into simethicone (n = 811) and non-simethicone groups (n = 475) as 2:1 PSM. The patients receiving simethicone had better remission rates of abdominal distension at both 24 h and 48 h after LC (49.2% vs. 34.7%, 83.9% vs. 74.8%, respectively), along with shorter time to the first flatus (14.6 ± 11.1 h vs. 17.2 ± 9.1 h, P < 0.001) compared to those without. Multiple logistic regression identified gallstone (OR = 0.33, P = 0.001), cholecystic polyp (OR = 0.53, P = 0.050), preoperative abdominal distention (OR = 0.63, P = 0.002) and simethicone use (OR = 1.89, P < 0.001) as independent factors contributing to the early remission of abdominal distension following LC. The prognosis model developed for predicting remission rates of abdominal distension within 24 h after LC yielded an area under the curve of 0.643 and internal validation a value of 0.644. CONCLUSIONS: Simethicone administration significantly enhanced the early remission of post-LC abdominal distension, particularly for patients who had gallstones, cholecystic polyp, prolonged anesthesia or preoperative abdominal distention. TRIAL REGISTRATION: ChiCTR2200064964 (24/10/2022).

Cold-adaptive evolution at the reproductive stage in Geng/japonica subspecies reveals the role of OsMAPK3 and OsLEA9.

Cold stress at the reproductive stage severely affects the production and geographic distribution of rice. The Geng/japonica subpopulation gradually developed stronger cold adaptation than the Xian/indica subpopulation during the long-term domestication of cultivated rice. However, the evolutionary path and natural alleles underlying the cold adaptability of intra-Geng subspecies remain largely unknown. Here, we identified MITOGEN-ACTIVATED PROTEIN KINASE 3 (OsMAPK3) and LATE EMBRYOGENESIS ABUNDANT PROTEIN 9 (OsLEA9) as two important regulators for the cold adaptation of Geng subspecies from a combination of transcriptome analysis and genome-wide association study. Transgenic validation showed that OsMAPK3 and OsLEA9 confer cold tolerance at the reproductive stage. Selection and evolution analysis suggested that the Geng version of OsMAPK3 (OsMAPK3Geng ) directly evolved from Chinese Oryza rufipogon III and was largely retained in high-latitude and high-altitude regions with low temperatures during domestication. Later, the functional nucleotide polymorphism (FNP-776) in the Kunmingxiaobaigu and Lijiangxiaoheigu version of the OsLEA9 (OsLEA9KL ) promoter originated from novel variation of intra-Geng was selected and predominantly retained in temperate Geng to improve the adaptation of Geng together with OsMAPK3Geng to colder climatic conditions in high-latitude areas. Breeding potential analysis suggested that pyramiding of OsMAPK3Geng and OsLEA9KL enhanced the cold tolerance of Geng and promotes the expansion of cultivated rice to colder regions. This study not only highlights the evolutionary path taken by the cold-adaptive differentiation of intra-Geng, but also provides new genetic resources for rice molecular breeding in low-temperature areas.

Genetic-based dissection of resistance to bacterial leaf streak in rice by GWAS.

BACKGROUND: Rice is the second-largest food crop in the world and vulnerable to bacterial leaf streak disease. A thorough comprehension of the genetic foundation of agronomic traits was essential for effective implementation of molecular marker-assisted selection. RESULTS: Our study aimed to evaluate the vulnerability of rice to bacterial leaf streak disease (BLS) induced by the gram-negative bacterium Xanthomonas oryzae pv. oryzicola (Xoc). In order to accomplish this, we first analyzed the population structure of 747 accessions and subsequently assessed their phenotypes 20 days after inoculation with a strain of Xoc, GX01. We conducted genome-wide association studies (GWAS) on a population of 747 rice accessions, consisting of both indica and japonica subpopulations, utilizing phenotypic data on resistance to bacterial leaf streak (RBLS) and sequence data. We identified a total of 20 QTLs associated with RBLS in our analysis. Through the integration of linkage mapping, sequence analysis, haplotype analysis, and transcriptome analysis, we were able to identify five potential candidate genes (OsRBLS1-OsRBLS5) that possess the potential to regulate RBLS in rice. In order to gain a more comprehensive understanding of the genetic mechanism behind resistance to bacterial leaf streak, we conducted tests on these genes in both the indica and japonica subpopulations, ultimately identifying superior haplotypes that suggest the potential utilization of these genes in breeding disease-resistant rice varieties. CONCLUSIONS: The findings of our study broaden our comprehension of the genetic mechanisms underlying RBLS in rice and offer significant insights that can be applied towards genetic improvement and breeding of disease-resistant rice in rapidly evolving environmental conditions.

Natural variation in Tiller Number 1 affects its interaction with TIF1 to regulate tillering in rice.

Tiller number per plant-a cardinal component of ideal plant architecture-affects grain yield potential. Thus, alleles positively affecting tillering must be mined to promote genetic improvement. Here, we report a Tiller Number 1 (TN1) protein harbouring a bromo-adjacent homology domain and RNA recognition motifs, identified through genome-wide association study of tiller numbers. Natural variation in TN1 affects its interaction with TIF1 (TN1 interaction factor 1) to affect DWARF14 expression and negatively regulate tiller number in rice. Further analysis of variations in TN1 among indica genotypes according to geographical distribution revealed that low-tillering varieties with TN1-hapL are concentrated in Southeast Asia and East Asia, whereas high-tillering varieties with TN1-hapH are concentrated in South Asia. Taken together, these results indicate that TN1 is a tillering regulatory factor whose alleles present apparent preferential utilization across geographical regions. Our findings advance the molecular understanding of tiller development.

RRS1 shapes robust root system to enhance drought resistance in rice.

A strong root system facilitates the absorption of water and nutrients from the soil, to improve the growth of crops. However, to date, there are still very few root development regulatory genes that can be used in crop breeding for agriculture. In this study, we cloned a negative regulator gene of root development, Robust Root System 1 (RRS1), which encodes an R2R3-type MYB family transcription factor. RRS1 knockout plants showed enhanced root growth, including longer root length, longer lateral root length, and larger lateral root density. RRS1 represses root development by directly activating the expression of OsIAA3 which is involved in the auxin signaling pathway. A natural variation in the coding region of RRS1 changes the transcriptional activity of its protein. RRS1T allele, originating from wild rice, possibly increases root length by means of weakening regulation of OsIAA3. Knockout of RRS1 enhances drought resistance by promoting water absorption and improving water use efficiency. This study provides a new gene resource for improving root systems and cultivating drought-resistant rice varieties with important values in agricultural applications.

Fabrication of CuInZnS/ZnS Quantum Dot Microbeads by a Two-Step Approach of Emulsification-Solvent Evaporation and Surfactant Substitution and Its Application for Quantitative Detection.

CuInS2 quantum dots (CIS QDs) are considered to be promising alternatives for Cd-based QDs in the fields of biology and medicine. However, high-quality hydrophobic CIS QDs are difficult to be transferred to water due to their 1-dodecylmercaptan (DDT) ligands. Therefore, the fluorescence and stability of the prepared aqueous CIS QDs is not enough to meet the requirement for sensitive detection. Here, as large as 13 nm CuInZnS/ZnS QDs with DDT ligands were first synthesized, and then, CuInZnS/ZnS microbeads (QBs) containing thousands of QDs were successfully fabricated by a two-step approach of emulsion-solvent evaporation and surfactant substitution. Through emulsion-solvent evaporation, the CuInZnS/ZnS QDs formed microbeads in the microemulsion with dodecyl trimethylammonium bromide (DTAB), and the Förster resonance energy transfer (FRET) has been effectively overcome. Then, CO-520 was introduced to substitute DTAB to improve the stability and water solubility. Lastly, the microbeads were coated with a SiO2 shell and carboxylated. Subsequently, the constructed QBs (∼210 nm) were used as labels in a fluorescence immunosorbent assay (FLISA) for quantitative detection of heart type fatty acid binding protein (H-FABP), and the limit of detection was 0.48 ng mL-1, which indicated a greatly improved detection sensitivity compared to that of the Cd-free QDs. The highly fluorescent and stable CuInZnS/ZnS QBs will have great application prospects in many biological fields.

Two unusual novel iridoid glycosides from Cornus officinalis fruit and their biological activities.

Two unusual novel iridoid glycosides, cornsecoside A (1) and cornsecoside B (2), were isolated from a 40% ethanol elution fraction of a 50% ethanol extract of Cornus officinalis fruit. Their structures were determined by spectroscopic data analysis combined with hydrolysis and ECD spectroscopy. In addition, compounds 1 and 2 exhibited cytotoxic activity against Bel-7402 cells with IC50 values of 8.12 and 9.31 µM, and were neuroprotective against H2O2-induced SH-SY5Y cell injure at a concentration of 10 µM.

Toxicity evaluation of chlorinated natural water using Photobacterium phosphoreum: Implications for ballast water management.

Chlorination of ballast water could produce harmful disinfection by-products (DBPs) and total residual oxidants. The International Maritime Organization calls for toxicity testing of discharged ballast water with fish, crustacea and algae to reduce the risk, but it is difficult to evaluate the toxicity of treated ballast water in a short time. Therefore, the purpose of this study was to analyze the applicability of luminescent bacteria to the assessment of residual toxicity of chlorinated ballast water. The toxicity unit for all treated samples were higher for Photobacterium phosphoreum than for microalgae (Selenastrum capricornutum and Chlorella pyrenoidosa), after adding neutralizer, all samples showed little effect on the luminescent bacteria and microalgae. For the DBPs, except for 2,4,6-Tribromophenol, Photobacterium phosphoreum could produce more sensitive and rapid test results than other species, the results in Photobacterium phosphoreum showed that the toxicity of DBPs in order of: 2,4-Dibromophenol > 2,6-Dibromophenol > 2,4,6-Tribromophenol > Monobromoacetic acid > Dibromoacetic acid > Tribromoacetic acid, and most binary mixtures (aromatic DBPs and aliphatic DBPs) presented synergistic effects based on the CA model. The aromatic DBPs in ballast water deserve more attention. In general, for ballast water management, the use of luminescent bacteria to evaluate the toxicity of treated ballast water and DBPs is desirable, this study could provide beneficial information for enhancing ballast water management.

Variations in OsSPL10 confer drought tolerance by directly regulating OsNAC2 expression and ROS production in rice.

Drought is a major factor restricting the production of rice (Oryza sativa L.). The identification of natural variants for drought stress-related genes is an important step toward developing genetically improved rice varieties. Here, we characterized a member of the SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) family, OsSPL10, as a transcription factor involved in the regulation of drought tolerance in rice. OsSPL10 appears to play a vital role in drought tolerance by controlling reactive oxygen species (ROS) production and stomatal movements. Haplotype and allele frequency analyses of OsSPL10 indicated that most upland rice and improved lowland rice varieties harbor the OsSPL10Hap1 allele, whereas the OsSPL10Hap2 allele was mainly present in lowland and landrace rice varieties. Importantly, we demonstrated that the varieties with the OsSPL10Hap1 allele showed low expression levels of OsSPL10 and its downstream gene, OsNAC2, which decreases the expression of OsAP37 and increases the expression of OsCOX11, thus preventing ROS accumulation and programmed cell death (PCD). Furthermore, the knockdown or knockout of OsSPL10 induced fast stomatal closure and prevented water loss, thereby improving drought tolerance in rice. Based on these observations, we propose that OsSPL10 confers drought tolerance by regulating OsNAC2 expression and that OsSPL10Hap1 could be a valuable haplotype for the genetic improvement of drought tolerance in rice.

RGN1 controls grain number and shapes panicle architecture in rice.

Yield in rice is determined mainly by panicle architecture. Using map-based cloning, we identified an R2R3 MYB transcription factor REGULATOR OF GRAIN NUMBER1 (RGN1) affecting grain number and panicle architecture. Mutation of RGN1 caused an absence of lateral grains on secondary branches. We demonstrated that RGN1 controls lateral grain formation by regulation of LONELY GUY (LOG) expression, thus controlling grain number and shaping panicle architecture. A novel favourable allele, RGN1C , derived from the Or-I group in wild rice affected panicle architecture by means longer panicles. Identification of RGN1 provides a theoretical basis for understanding the molecular mechanism of lateral grain formation in rice; RGN1 will be an important gene resource for molecular breeding for higher yield.

Biomolecular Surface Functionalization and Stabilization Method to Fabricate Quantum Dots Nanobeads for Accurate Biosensing Detection.

The surface functionalization of quantum dots (QDs) is essential for their application as a label material in a biological field. Here, a protein surface functionalization approach was introduced to combine with silica encapsulation for the sustainable and stable synthesis of QDs nanobeads for biomarker detection. The formation of QDs nanobeads was achieved by multiple mercapto groups in bovine serum albumin (BSA) macromolecules as multidentate ligands to replace hydrophobic ligands on the surface of QDs and decompression. The resulting QDs nanobeads exhibited 20 times more photoluminescence than the corresponding hydrophobic QDs and presented excellent stability under physiological conditions due to the protection of BSA and silica. The nanobeads served as a robust signal-generating reagent to construct the lateral flow immunoassay (LFIA) biosensor for the detection of glycosylated hemoglobin (HbA1c). The concentration of HbA1c was determined within 10 min with high specificity using only 60 µL of whole blood samples collected clinically. The nanobeads-based LFIA biosensor exhibited linear detection of HbA1c from 4.2% to 13.6%. The accuracy and stability of this approach in clinical utility was demonstrated by the detection of HbA1c after a long-term storage of test strips. This protein surface modification technology provides a new way for improving the biological properties of QDs in clinical diagnosis.

Papaverine Infusion Through Aortic Root before Cardiac Self-recovery in Heart Valve Replacement with TiO2 Nanocrystalline Film Material.

This work was to investigate TiO2 nanocrystalline film material in heart valve replacement (HVR) and the effect of papaverine infusion through the aortic root before cardiac self-recovery during the HVR. TiO2 nanocrystalline films were prepared by radio frequency (RF) reactive sputtering. The crystallization characteristics and surface morphology of TiO2 nanocrystalline films were observed by X-ray diffraction and scanning electron microscopy, and the anti-platelet adhesion and anti-coagulation properties of the films were analyzed. 86 patients with heart valve disease were selected and all underwent HVR. They were randomly divided into a control group (routine treatment) and an experimental group (papaverine perfusion through aortic root), with 43 cases in each group. The rate of cardiac self-recovery and the dosage of dopamine were observed. The results showed that the TiO2 nanocrystalline film was composed of a large number of uniform particles, and the average particle size was about 18.97 ± 7.28 nm. The rate of cardiac self-recovery in the experimental group was 97.67%, which was significantly higher than that in the control group (67.44%) (P< 0.05). The dosage of epinephrine, dopamine, and duration of cardiopulmonary bypass (CPB) assistance in the observation group were less than those in the control group (P < 0.05). These results indicated that TiO2 nanocrystalline film could be used in HVR, and papaverine infusion through aortic root before HVR and myocardial protection measures can significantly improve the rate of cardiac self-recovery and promote postoperative recovery.