Mother-reliant or Self-reliant: The germination strategy of seeds in a species-rich alpine meadow is associated with the existence of pericarps.

BACKGROUND AND AIMS: Some plants germinate their seeds enclosed by a pericarp, while others lack the outer packaging. As a maternal tissue, may impart seeds with different germination strategies. Plants in a community with different flowering times may separately disperse and germinate their seeds; therefore, flowering time can be considered as one manifestation of maternal effects on offspring. The mass of the seed is another important factor influencing germination and represents the intrinsic resource of seed that supports the germination. Using seeds from a species-rich alpine meadow located in the Hengduan Mountains of China, a global biodiversity hotspot, we aim to illustrate whether and how the type of seed (with and without a pericarp) modulates the interaction of flowering time and seed mass with germination. METHODS: Seeds were germinated under a generally favorable condition and germination speed (estimated by mean germination time, MGT) was calculated. We quantified the maternal conditions by separation of flowering time for 67 species in the meadow, in which 31 produced seeds with pericarps and 36 yielded seeds without pericarps, respectively. We also weighed one hundred seeds to assess their mass. KEY RESULTS: The MGT varied between the two types of seed. For seeds with pericarps, MGT was associated with flowering time but not with seed mass. Plants with earlier flowering times in the meadow exhibited more rapid seed germination. For seeds without pericarp, the MGT depended on seed mass, with smaller seeds germinating more rapidly than larger seeds. CONCLUSIONS: The distinct responses of germination to flowering time and seed mass observed in seeds with and without pericarp suggest that germination strategies might be mother-reliant for seeds protected by pericarps but self-reliant for those without such protection. This novel finding improves our understanding of seed germination by integrating ecologically mediated maternal conditions and inherent genetic properties.

Effect of quality nursing intervention on wound healing in patients with burns: A meta-analysis.

This meta-analysis aimed to explore the effects of quality nursing intervention on wound healing in patients with burns. A computerised search was conducted for randomised controlled trials (RCTs) on the effect of quality nursing intervention on wound healing in patients with burns in the PubMed, Embase, Google Scholar, Cochrane Library, China National Knowledge Infrastructure and Wanfang databases from the date of database inception to November 2023. Two researchers independently screened the literature, extracted data and performed quality assessment based on the inclusion and exclusion criteria. Stata 17.0 software was used for the data analysis. Twenty-nine RCTs involving 2637 patients with burns were included. The meta-analysis revealed that compared with conventional nursing, the implementation of quality nursing intervention in patients with burns significantly shortened the wound healing time (standardised mean difference [SMD] = -2.93, 95% confidence interval [CI]: -3.44 to -2.42, p < 0.001). The incidence of wound infections (odds ratio [OR] = 0.14, 95% CI: 0.07-0.27, p < 0.001) and complications (OR = 0.16, 95% CI: 0.11-0.23, p < 0.001) was also reduced significantly. This meta-analysis shows that applying quality nursing interventions in patients with burns can significantly shorten the wound healing time and reduce the incidence of wound infection and complications, thus promoting early patient recovery.

Immunological mechanisms and treatable traits of chronic rhinosinusitis in Asia: A narrative review.

OBJECTIVES: To review the current literature on immunological mechanisms and treatable traits of chronic rhinosinusitis (CRS) in Asia. DESIGN: This is a narrative review of published data on the immunological mechanisms and treatable traits of CRS in Asia. Published English literature on CRS in Asian and Western countries was reviewed. Where available, the data extracted included epidemiology, immunology, bacterium, phenotype, endotype and treatment. RESULTS AND CONCLUSION: CRS is a heterogeneous disease characterised by persistent locoregional mucosal inflammation of the paranasal sinuses. The inflammatory signatures of CRS vary across patients with distinct racial and ethnic backgrounds and geographic areas. Compared to CRS patients in Western countries, Asian CRS patients display less eosinophilic and Type 2 inflammation, which is associated with lower asthma and allergic rhinitis comorbidities. In contrast, Asian patients with CRS have more prominent non-eosinophilic inflammation than those in Western countries. In addition, Asian CRS patients may have different bacterial colonisation than patients in Western countries. Our review suggests that the distinct immunological mechanisms between Asian and Western CRS patients may influence the clinical phenotype, responses to treatment and outcomes. The treatable trait is a new strategy and therapeutic target identified by phenotype or endotype and has been proposed as a new paradigm for the management of diseases. Improved understanding of CRS phenotypic and endotypic heterogeneity and incorporation of treatable traits into clinical care pathways may facilitate more effective selections of therapeutic interventions, including surgery and biologics.

Ratiometric detection of p-nitrophenol and its derivatives using a dual-emissive neuron cell-like carbonized probe based on a ππ stacking quenching mechanism.

p-Nitrophenol and its derivatives can cause serious harm to the health of mankind and the earth's ecosystem. Therefore, it is necessary to develop a novel and rapid detection technology for p-nitrophenol and its derivative. Herein, excellent water-soluble, large-size and dual-emissive neuron cell-analogous carbon-based probes (NCNPs) have been prepared via a solvothermal approach, using o-phenylenediamine as the only precursor, which exhibit two distinctive fluorescence (FL) peaks at 420 and 555 nm under 345 nm excitation. The NCNPs show a neuron cell-like branched structure, are cross-connected, and are in the range of 10-20 nm in skeleton diameter. Interestingly, their blue-green dual-colour fluorescence is quenched by p-nitrophenol or its derivative due to the specific mechanism of the ππ stacking interactions or internal filtration effect. Accordingly, a simple, rapid, direct and free-label ratiometric FL detection of p-nitrophenol is proposed. An excellent linear relationship shows linear regions over the range of 0.1-50 µM between the ratio of the FL intensity (FL555 nm/FL420 nm) and the concentrations of p-nitrophenol. The detection limit is as low as 43 nM (3σ). Importantly, the NCNP-based probe also shows acceptable repeatability and reproducibility for the detection of p-nitrophenol and its derivatives, and the recovery results for p-nitrophenol in real wastewater samples are favourable.

Palladium/N,N'-Disulfonyl Bisimidazoline-Catalyzed Enantioselective Addition of Arylboronic Acids to Cyclic N-Sulfonyl Ketimines.

The combination of Pd(TFA)2 and an N,N'-disulfonyl bisimidazoline ligand shows high catalytic activity and excellent asymmetric induction in the addition of arylboronic acids to cyclic N-sulfonyl ketimines including benzo[d]isothiazole-1,1-dioxides, benzo[e][1,2,3]oxathiazine-2,2-dioxides, and 1,2,5-thiadiazole-1,1-dioxides, by which three types of chiral quaternary carbon-containing sultams with substantial substitution diversity were synthesized with high yields and excellent enantioselectivities (up to >99% ee). The current catalysis demonstrated a remarkable tolerance to oxygen and thus provided an operationally simple approach for constructing enantioenriched cyclic quaternary stereocenters.

Genome-wide identification and expression analysis of the SPL gene family in woodland strawberry Fragaria vesca.

SQUAMOSA promoter-binding protein-like (SPL) is a class of plant-specific transcription factors that play critical roles in regulating plant growth and development. However, little systematic research on SPL genes has been conducted in strawberry. In this study, 14 SPL genes were identified in the genome of woodland strawberry (Fragaria vesca), one of the model plants of the family Rosaceae. Chromosome localization analysis indicated that the 14 FvSPL genes were unevenly distributed on six chromosomes. Phylogenetic analysis indicated that the FvSPL proteins could be clustered into six groups (G1 to G6). Genes with similar structure were classified into the same group, implying their functional redundancy. In addition, nine out of the 14 FvSPL genes, belonging to G1, G2, and G5, were found to be the putative targets of FvmiR156 genes. Expression analysis indicated FvSPL genes exhibited highly diverse expression patterns in the tissues and organs examined. The transcript levels of most FvmiR156-targeted FvSPL genes in fruit were lower than those non-miR156-targeted genes. In addition, the expression of the FvmiR156-targeted FvSPL genes decreased during fruit ripening, whereas the expression of FvmiR156 genes increased in fruit during this process. The results provide a foundation for future functional analysis of FvSPL genes in strawberry growth and development.

Supramolecular nanofiber of pyrene-lactose conjugates and its two-photon fluorescence imaging.

A lactose modified pyrene derivative (Py-Lac) was synthesized, with which novel twisted supramolecular nanofibers in diameter about 20 nm were constructed by self-assembly. The nanofibers showed solid-state fluorescence between 400 nm and 650 nm with the maximum emission at 495 nm. Furthermore, its recognition reaction with PNA lectin was investigated by fluorescence spectra and turbidity assays. It is interesting found that the supramolecular assembly as multivalent glycocluster exhibited unique and selectively binding interactions with PNA lectin with the binding constant of 5.74 × 106 M-1. Moreover, compound Py-Lac showed two-photon fluorescence imaging with Hep G2 cells.

[Study on mechanism of hepatotoxicity of Ploygoni Multiflori Caulis based on function inhibition of bilirubin-associated transporters in idiosyncratic rat].

To explore the possible mechanism of liver injury, the effects of Ploygoni Multiflori Caulis and its extractive on the function of bilirubin-associated transporters were investigated in normal (N) and idiosyncratic (LPS) rats (M). The normal and LPS rats were respectively administrated powder of Ploygoni Multiflori Caulis, its extractive and same volume of 0.5% CMC-Na solution for 7 d. BSP, a substrate of the transporters of Oatp1a1 and Oatp1b2 was selected, and its pharmacokinetic parameters of intravenous injection were determined to examined the activity these transporters. Meanwhile the mRNA expressions of transporters were detected. Compared with N-blank control group, besides M-powder group, the Cmax has no significantly different from other groups, t1/2, AUC0-t and AUC0-∞ were significantly increased, and CL were significantly decreased. However, compared with N- blank control group, AST and ALT decreased significantly. The expression of Oatp1a1, Oatp1b2 and MRP2 mRNA was significantly decreased (P<0.05), but there was no act synergistically when Ploygoni Multiflori Caulis and extractive were combined with LPS. The function of Oatp1a1, Oatp1b2 and MRP2 in rats were significantly inhibited by Ploygoni Multiflori Caulis and extractive, which may be an important cause of hepatotoxicity.

[In vitro effects of Genkwa Flos chloroform extract on activity of human liver microsomes UGTs and UGT1A1].

To predict the mechanism of liver injury induced by Genkwa Flos, we investigated the effect of chloroform extract on UGTs and UGT1A1 activities of the liver microsomes in rat and human. In the present study, 4-nitrophenol(4-NP) and ß-estradiol were elected as substrates to determine activities of UGTs and UGT1A1 by UV and HPLC. The results showed that there were 1.00% of apigenin, 6.40% of hydroxygenkwanin and 18.38% of genkwanin in chloroform extract; and total diterpene mass fraction was 31.40%. Compared with the control group, chloroform extract could significantly inhibit the activity of UGTs in rat liver microsomes(RLM) system, while the inhibitory effect was not obvious in human liver microsomes(HLM) system. UGT1A1 activity was inhibited by chloroform extract in rat liver microsomes and human liver microsomes (based on genkwanin, IC50=8.76, 10.36 µmol•L⁻¹). The inhibition types were non-competitive inhibition(RLM) and uncompetitive inhibition(HLM). In conclusion, the results indicated that chloroform extract showed different inhibitory effects on UGTs and UGT1A1 activity, which may be one of the mechanisms of liver injury induced by Genkwa Flos.

Anesthesia, Anesthetics, and Postoperative Cognitive Dysfunction in Elderly Patients.

Postoperative cognitive dysfunction (POCD) remains a major issue that worsens the prognosis of elderly surgery patients. This article reviews the current research on the effect of different anesthesia methods and commonly utilized anesthetics on the incidence of POCD in elderly patients, aiming to provide an understanding of the underlying mechanisms contributing to this condition and facilitate the development of more reasonable anesthesia protocols, ultimately reducing the incidence of POCD in elderly surgery patients.

Electron ultra-high dose rate FLASH irradiation study using a clinical linac: Linac modification, dosimetry, and radiobiological outcome.

PURPOSE: Ultra-high dose rate FLASH irradiation (FLASH-IR) has been shown to cause less normal tissue damage compared with conventional irradiation (CONV-IR), this is known as the "FLASH effect." It has attracted immense research interest because its underlying mechanism is scarcely known. The purpose of this study was to determine whether FLASH-IR and CONV-IR induce differential inflammatory cytokine expression using a modified clinical linac. MATERIALS AND METHODS: An Elekta Synergy linac was used to deliver 6 MeV CONV-IR and modified to deliver FLASH-IR. Female FvB mice were randomly assigned to three different groups: a non-irradiated control, CONV-IR, or FLASH-IR. The FLASH-IR beam was produced by single pulses repeated manually with a 20-s interval (Strategy 1), or single-trigger multiple pulses with a 10 ms interval (Strategy 2). Mice were immobilized in the prone position in a custom-designed applicator with Gafchromic films positioned under the body. The prescribed doses for the mice were 6 to 18 Gy and verified using Gafchromic films. Cytokine expression of three pro-inflammatory cytokines (tumor necrosis factor-α [TNF-α], interferon-γ [IFN-γ], interleukin-6 [IL-6]) and one anti-inflammatory cytokine (IL-10) in serum samples and skin tissue were examined within 1 month post-IR. RESULTS: The modified linac delivered radiation at an intra-pulse dose rate of around 1 × 106 Gy/s and a dose per pulse over 2 Gy at a source-to-surface distance (SSD) of 13 to 15 cm. The achieved dose coverage was 90%-105% of the maximum dose within -20 to 20 mm in the X direction and 95% within -30 to 30 mm in the Y direction. The absolute deviations between the prescribed dose and the actual dose were 2.21%, 6.04%, 2.09%, and 2.73% for 6, 9, 12, and 15 Gy as measured by EBT3 films, respectively; and 4.00%, 4.49%, and 2.30% for 10, 14, and 18 Gy as measured by the EBT XD films, respectively. The reductions in the CONV-IR versus the FLASH-IR group were 4.89%, 10.28%, -7.8%, and -22.17% for TNF-α, IFN-γ, IL-6, and IL-10 in the serum on D6, respectively; 37.26%, 67.16%, 56.68%, and -18.95% in the serum on D31, respectively; and 62.67%, 35.65%, 37.75%, and -12.20% for TNF-α, IFN-γ, IL-6, and IL-10 in the skin tissue, respectively. CONCLUSIONS: Ultra-high dose rate electron FLASH caused lower pro-inflammatory cytokine levels in serum and skin tissue which might mediate differential tissue damage between FLASH-IR and CONV-IR.

[The anatomy features and surgical significance of the pulmonary circuits of pulmonary atresia with ventricular septal defect and major aortopulmonary collateral arteries].

OBJECTIVES: To analyze the anatomy features of the pulmonary circuits in the patients with pulmonary atresia (PA) with ventricular septal defect (VSD) and major aortopulmonary collateral arteries (MAPCA), and discuss the clinical significance. METHODS: From April 2002 to June 2010, the anatomy features of pulmonary circuits in 33 patients with PA/VSD/MAPCA were examined and analyzed. There were 21 male and 12 female patients. The age ranged from 11 months to 29 years. The anatomic types of PA/VSD included group B for 22 cases, group C for 11 cases. Thirty-one patients of them underwent 33 operative procedures. The operations included aorta-pulmonary shunt in 8 cases, one stage unifocalization with VSD open in 2 cases, complete repair in 23 cases. RESULTS: Twenty-nine (87.9%) patients had native pulmonary arteries, 6 of them were normal size and 23 were hypoplastic size. Four patients (12.1%) had no native pulmonary arteries. The postoperative oxygen saturation of the patients undergone shunt and one stage unifocalization was increased to 83% to 90%. There was one early death after complete repair because of multiorgan function failure. There were 4 cases of severe low cardiac output and 3 cases of respiratory function failure. Sixteen patients after complete repair were followed up more than one year. The postoperative right ventricular pressure was 41 to 99 mmHg (1 mmHg = 0.133 kPa). The ejection fraction value was more than 50% in 14 patients and less than 50% in 2 patients. Two patients had medium pulmonary insufficiency. CONCLUSIONS: An individualized approach based on the anatomy of the pulmonary circuits permits achievement in the patients with PA/VSD/MAPCA. The surgical strategy for PA/VSD/MAPCA mainly depends on the anatomy features of native pulmonary arteries, confluent pulmonary arteries and MAPCA.

Correction: Synthesis, self-aggregation and cryopreservation effects of perylene bisimide-glycopeptide conjugates.

Correction for 'Synthesis, self-aggregation and cryopreservation effects of perylene bisimide-glycopeptide conjugates' by Xu He et al., Chem. Commun., 2021, DOI: 10.1039/d1cc03835d.

Synthesis, self-aggregation and cryopreservation effects of perylene bisimide-glycopeptide conjugates.

Three perylene bisimide-glycopeptide conjugates (PBI-AFF-Man, PBI-AFF-Glu and PBI-AFF-Gal) were synthesized, which showed moderate activity in the control of ice crystal growth. Furthermore, the cellular cryopreservation effects of PBI-AFF-Man, PBI-AFF-Glu and PBI-AFF-Gal showed enhancements in cell viabilities, especially for PBI-AFF-Glu with values of 22.77 ± 3.33% (HeLa cells), 19.43 ± 1.90% (A549 cells) and 16.63 ± 1.76% (GES-1 cells) at a dose of 1.0 mg mL-1. This work will help guide the development of self-assembled cryoprotectants.

Myocardial ischaemic and diazoxide preconditioning both increase PGC-1alpha and reduce mitochondrial damage.

OBJECTIVES: Pretreatment with diazoxide, a mitochondrial ATP-sensitive potassium channel (mito KATP) opener, was found to protect the rat heart against ischaemia-reperfusion (I/R) injury by mimicking ischaemic preconditioning (IPC). However, the protection mechanisms have not been fully clarified yet.We hypothesize that molecular regulation of mitochondrial energetics is integral to this cardioprotective programme. We explored the involvement of peroxisome proliferator-activated receptor gamma coactivator-1-1alpha (PGC-1alpha) in the effect of IPC and diazoxide preconditioning (DPC) with regard to its role in protection against I/R injury. METHODS: 30 Wistar rats were used to establish the Langendorff isolated perfused heart model. Rats were randomly divided into 5 groups, 6 in each group: (1) the I/R group: after 30 min of equilibration perfusion, the heart was subjected to 30 min of ischaemia and 1 h of reperfusion; (2) the IPC group: after 10 min of equilibration perfusion, the heart was subjected to two times 5 min ischaemia and 5 min of reperfusion, followed by 30 min of ischaemia and 1 h of reperfusion; (3) the DPC group: after 10 min of equilibration perfusion, the heart was given two times a K-H perfusion solution containing diazoxide (100 micromol/l) for 5 min then a non-diazoxide K-H perfusion solution for 5 min, followed by 30 min of ischaemia and 1 h of reperfusion; (4) a blank control group: an equal amount of saline was used instead of diazoxide. The perfusion procedure was the same as in the DPC group; (5) the dimethyl sulfoxide (DMSO) group: DMSO was applied instead of diazoxide, and the perfusion procedure was the same as in the DPC group. Cardiac apex muscle was cut for frozen section. Immunohistochemistry staining of PGC-1alpha was performed and average absorbance was calculated. An electron microscope was used for Flameng scoring of the myocardial mitochondria. RESULTS: The average absorbance values of PGC-1alpha were: I/R group (3.88 +/- 1.72), IPC group (10.94 +/- 5.23), DPC group (8.40 +/- 3.64), blank control group (3.55 +/- 1.56) and DMSO group (4.16 +/- 0.52), respectively. The expression of PGC- 1alpha was significantly increased in the IPC and DPC groups and the differences were statistically significant compared to the I/R, blank control and DMSO groups, i.e., P < 0.01 for IPC group and P < 0.05 for DPC group. However, there was no significant difference between the IPC and DPC groups (P > 0.05). Flameng score: IPC group (0.44 +/- 0.13), DPC group (0.47 +/- 0.10), I/R group (1.78 +/- 0.14), blank control group (1.70 +/- 0.03) and DMSO group (1.68 +/- 0.06). The Flameng score of the IPC and DPC groups was statistically significantly different as compared to the I/R group, blank control group and DMSO group (P < 0.01), but no significant difference was detected between the IPC and DPC groups (P > 0.05). CONCLUSION: IPC and DPC have a protective effect on myocardial mitochondria, and their mechanism of action may be related to activation and over-expression of PGC-1alpha.

Yb(OTf)3-Catalyzed Alkyne-Carbonyl Metathesis-Oxa-Michael Addition Relay for Diastereoselective Synthesis of Functionalized Naphtho[2,1-b]furans.

A new Lewis acid catalyzed alkyne-carbonyl metathesis/oxa-Michael addition relay was first reported, leading to the atom-economic synthesis of unreported functionalized indolone-containing naphtho[2,1-b]furan-1-ones with a quaternary center in good to excellent yields and high diastereoselectivity through scission/recombination of C-O double bonds under the mild conditions. A Yb(OTf)3-catalyzed reaction between α-alkynyl naphthalen-2-ols and isatins worked efficiently and offered a convergent and regioselective protocol to construct cyclic ketones via alkyne polyfunctionalization.

[Diabetes counteracts the protective effect of the diazoxide preconditioning on ischemic reperfused rat heart].

OBJECTIVE: To explore the impact of diabetic condition on the protective effect of diazoxide preconditioning (DPC) on ischemic-reperfused (I/R) myocardium in rats. METHODS: Thirty normal male Sprague-Dawley rats were divided into 3 groups, including non-diabetic control group, non-diabetic I/R group, and non-diabetic I/R DPC group. Thirty diabetic male rats were also divided into the same 3 groups. The Langendorff isolated heart perfusion models were established. The control groups had a 90 min perfusion without any intervention. The I/R groups had a 30 min equilibration period, a 30 min ischemia, and a 30 min reperfusion. The I/R DPC groups had a 10 min equilibration, two cycles of 100 micromol/L diazoxide perfusion, 5 min each, followed by a 5 min diazoxide-free period before the 30 min ischemia and a 30 min reperfusion. The recovery rate of the left ventricular function, including cardiac output, left ventricular developed pressure (LVDP), and the maximum change rate of left ventricular pressure rise and fall (+/- dp/dt(max)) were recorded. The activity of creatine kinase in coronary outflow and activities of malonyldialdehyde, and superoxide dismutase in myocardium were detected. Myocardial water content was also assessed. RESULTS: In non-diabetic rats, the content of creatine kinase, malonyldialdehyde and water content were significantly decreased in I/R DPC group compared with those in I/R group. Furthermore, in I/R DPC group, the activity of superoxide dismutase and the recovery rate of the left ventricular function, including cardiac output, LVDP and +/- dp/dt(max), were significantly increased compared with those in I/R group (P < 0.05). By contrast, there were no significant changes between I/R DPC group and I/R group in diabetic rats (P > 0.05). CONCLUSION: Diabetes counteracts the protective effect of the diazoxide preconditioning on ischemic reperfused rat heart, which may be related with acute insulin resistance in cardiomyocytes.

Role of nitric oxide during early phase myocardial ischemic preconditioning in rats.

BACKGROUND: To date, there have been no reports on altered nitric oxide (NO) content in ischemia/reperfusion with regard to in vivo preconditioning procedures. These studies are important for understanding the mechanisms of NO during early myocardial ischemic preconditioning. The aim of the present study was to investigate the mechanisms of NO during early myocardial ischemic preconditioning by measuring levels of NO and cyclic guanosine monophosphate (cGMP), as well as activity of nitric oxide synthase (NOS) in ischemia/reperfusion with respect to preconditioning in rats. METHODS: Sixty-six female Sprague-Dawley rats were randomly divided into four groups: ischemic preconditioning group (IP), ischemia/reperfusion group (I/R), control group (CON), and preconditioning procedure group (PC). In the PC group, rats were further divided into PC1-, PC1 +, PC2-, PC2 +, PC3-, and PC3 + subgroups. Rats underwent left coronary artery occlusion and reperfusion, and subsequently, NOS activity and levels were assessed with spectrophotometric analysis. cGMP contents were measured with radioimmunoassay. RESULTS: The level of NO and cGMP, as well as the activity of NOS, were significantly higher in the IP group compared to the I/R and CON groups (P < 0.05). During preconditioning prior to prolonged ischemia, NO and cGMP levels varied markedly with ischemia and reperfusion. The levels of NO repeatedly increased when the heart was exposed to three episodes of 5-minute ischemia, and were almost completely reversed during each reperfusion period. NO and cGMP levels were significantly different between the 5-minute period of ischemia and the same period of reperfusion during preconditioning. CONCLUSIONS: NO plays an important role during early phase myocardial ischemic preconditioning in rats. NO and cGMP could be triggers and mediators of early phase myocardial ischemic preconditioning. Altered NOS activity following ischemic stress could be the primary inducer of higher NO levels detected. NO and cGMP fluctuations might be the trigger for protection during early phase myocardial ischemic preconditioning.

[Protective effect of ischemia and diazoxide preconditioning on postischemic reperfused myocardium and possible mechanism thereof].

OBJECTIVE: To study the protective mechanism of ischemic preconditioning (IPC) and diazoxide preconditioning (DPC) against myocardium ischemia-reperfusion (I/R) injury. METHODS: The hearts were taken out from 30 male Wistar rats and were divided randomly into 3 equal groups: I/R group undergoing 30-min equilibration perfusion and 30-min ischemia and then 60-min reperfusion, IPC group undergoing 10-min equilibration perfusion and then two cycles of 5 min ischemia interspersed with 5 min reperfusion prior to 30 min ischemia and a 60-min reperfusion, and DPC group undergoing 10-min equilibration perfusion and 2 cycles of 5 min of 100 microM diazoxide perfusion followed by 5-min drug-free period before the 30 min ischemia and 60-min reperfusion. Frozen sections of myocardium at the cardiac apex were made and immunohistochemical staining was used to detect the expression of peroxisome proliferator-activated receptor-gamma coactivator 1alpha (PGC-1alpha). Ultrathin sections 70 nm thick were made and transmission electron microscopy was used to detect the structure of the mitochondria with the Flameng scoring system. RESULTS: The PGC-1alpha expression of the IPC and DPC groups were significantly higher than that of the I/R group (P<0.01 and P<0.05), however, there was no significant difference in PGC-1alpha is expression between the IPC and DPC groups (P >0.05). The Flameng scores of the IPC and DPC groups were 0.44 +/- 0.13 and 0.47 +/- 0.10 respectively, both significantly higher than that of the I/R group (1.78 +/- 0.14, both P <0.01), however, there was no significant difference between IPC and DPC groups (P>0.05). CONCLUSION: IPC and DPC can protect myocyte mitochondria from the injury of ischemia/ reperfusion. The cardioprotective effects of IPC and DPC may be concerned with the activation and high expression of PGC-1alpha.