Chlorogenic acid alleviates hypoxic-ischemic brain injury in neonatal mice

Recent studies have shown that chlorogenic acid(CGA),which is present in coffee,has protective effects on the nervous system.However,its role in neonatal hypoxic-ischemic brain injury remains unclear.In this study,we established a newborn mouse model of hypoxic-ischemic brain injury using a modified Rice-Vannucci method and performed intraperitoneal injection of CGA.We found that CGA intervention effectively reduced the volume of cerebral infarct,alleviated cerebral edema,restored brain tissue structure after injury,and promoted axon growth in injured brain tissue.Moreover,CGA pretreatment alleviated oxygen-glucose deprivation damage of primary neurons and promoted neuron survival.In addition,changes in ferroptosis-related proteins caused by hypoxic-ischemic brain injury were partially reversed by CGA.Furthermore,CGA intervention upregulated the expression of the key ferroptosis factor glutathione peroxidase 4 and its upstream glutamate/cystine antiporter related factors SLC7A11 and SLC3A2.In summary,our findings reveal that CGA alleviates hypoxic-ischemic brain injury in neonatal mice by reducing ferroptosis,providing new ideas for the treatment of neonatal hypoxic-ischemic brain injury.

Transplantation of human placental chorionic plate-derived mesenchymal stem cells for repair of neurological damage in neonatal hypoxic-ischemic encephalopathy

Neonatal hypoxic-ischemic encephalopathy is often associated with permanent cerebral palsy,neurosensory impairments,and cognitive deficits,and there is no effective treatment for complications related to hypoxic-ischemic encephalopathy.The therapeutic potential of human placental chorionic plate-derived mesenchymal stem cells for various diseases has been explored.However,the potential use of human placental chorionic plate-derived mesenchymal stem cells for the treatment of neonatal hypoxic-ischemic encephalopathy has not yet been investigated.In this study,we injected human placental chorionic plate-derived mesenchymal stem cells into the lateral ventricle of a neonatal hypoxic-ischemic encephalopathy rat model and observed significant improvements in both cognitive and motor function.Protein chip analysis showed that interleukin-3 expression was significantly elevated in neonatal hypoxic-ischemic encephalopathy model rats.Following transplantation of human placental chorionic plate-derived mesenchymal stem cells,interleukin-3 expression was downregulated.To further investigate the role of interleukin-3 in neonatal hypoxic-ischemic encephalopathy,we established an in vitro SH-SY5Y cell model of hypoxic-ischemic injury through oxygen-glucose deprivation and silenced interleukin-3 expression using small interfering RNA.We found that the activity and proliferation of SH-SY5Y cells subjected to oxygen-glucose deprivation were further suppressed by interleukin-3 knockdown.Furthermore,interleukin-3 knockout exacerbated neuronal damage and cognitive and motor function impairment in rat models of hypoxic-ischemic encephalopathy.The findings suggest that transplantation of hpcMSCs ameliorated behavioral impairments in a rat model of hypoxic-ischemic encephalopathy,and this effect was mediated by interleukin-3-dependent neurological function.

Diffusion tensor imaging of neural tract injury in a patient with hypoxic-ischemic brain injury

Hypoxic-ischemic brain injury （HI-BI） is one of the most common causes of severe neurological disability, Some studies have reported diffusion tensor imaging （DTI） findings of neonatal patients with HI-BI. However, very little is known about DTI in the adult brain. The present study reports on a 15-year-old male patient with HI-BI, who exhibited no specific focal lesions on conventional brain MRI at 5 weeks. However, neural tract injuries were revealed by DTI. Seven control subjects were also evaluated. The patient suffered from cardiac arrest due to ventricular fibrillation for a period of 10 15 minutes. At 4 weeks after onset of cardiac arrest, although he was conscious and alert, he exhibited mild quadriparesis and severe cognitive dysfunction. DTI was acquired at 5 weeks after HI-BI onset. Decreased fractional anisotropy or voxel number of neural tracts suggested partial injury of the corticospinal tract, fornix, and cingulum. Disruptions of the fornix and cingulum on DTI confirmed neural tract injury. DTI could serve as a useful tool for evaluating the state of neural tracts in patients with HI-BI.

Hyperbaric oxygen treatment promotes neural stem cell proliferation in the subventricular zone of neonatal rats with hypoxic-ischemic brain damage

Hyperbaric oxygen therapy for the treatment of neonatal hypoxic-ischemic brain damage has been used clinically for many years, but its effectiveness remains controversial. In addition, the mechanism of this potential neuroprotective effect remains unclear. This study aimed to investigate the influence of hyperbaric oxygen on the proliferation of neural stem cells in the subventricular zone of neonatal Sprague-Dawley rats （7 days old） subjected to hypoxic-ischemic brain damage. Six hours after modeling, rats were treated with hyperbaric oxygen once daily for 7 days. Immunohistochemistry revealed that the number of 5-bromo-2＇-deoxyuridine positive and nestin positive cells in the subventricular zone of neonatal rats increased at day 3 after hypoxic-ischemic brain damage and peaked at day 5. After hyperbaric oxygen treatment, the number of 5-bromo-2＇- deoxyuddine positive and nestin positive cells began to increase at day 1, and was significantly higher than that in normal rats and model rats until day 21. Hematoxylin-eosin staining showed that hyperbaric oxygen treatment could attenuate pathological changes to brain tissue in neonatal rats, and reduce the number of degenerating and necrotic nerve cells. Our experimental findings indicate that hyperbaric oxygen treatment enhances the proliferation of neural stem cells in the subventricular zone of neonatal rats with hypoxic-ischemic brain damage, and has therapeutic potential for promoting neurological recovery following brain injury.

Mild hypothermia combined with neural stem cell transplantation for hypoxic-ischemic encephalopathy: neuroprotective effects of combined therapy

Neural stem cell transplantation is a useful treatment for ischemic stroke, but apoptosis often occurs in the hypoxic-ischemic environment of the brain after cell transplantation. In this study, we determined if mild hypothermia （27-28~C） can increase the survival rate of neural stem cells （1.0 x 105/~tL） transplanted into neonatal mice with hypoxic-ischemic encephalopathy. Long-term effects on neurological functioning of the mice were also examined. After mild hy- pothermia combined with neural stem cell transplantation, we observed decreased expression levels of inflammatory factor nuclear factor-kappa B and apoptotic factor caspase-3, reduced cerebral infarct volumes, increased survival rate of transplanted cells, and marked improvements in neurological function. Thus, the neuroprotective effects of mild hypothermia combined with neural stem cell transplantation are superior to those of monotherapy. Moreover, our findings suggest that the neuroprotective effects of mild hypothermia combined with neural stem cell transplantation on hypoxic-ischemic encephalopathy are achieved by anti-inflammatory and an- ti-apoptotic mechanisms.

The role of pineal microRNA-325 in regulating circadian rhythms after neonatal hypoxic-ischemic brain damage

Circadian rhythm disorder is a common,but often neglected,consequence of neonatal hypoxic-ischemic brain damage(HIBD).However,the underlying molecular mechanisms remain largely unknown.We previously showed that,in a rat model of HIBD,up-regulation of microRNA-325(miR-325)in the pineal gland is responsible for the suppression of Aanat,a key enzyme involved in melatonin synthesis and circadian rhythm regulation.To better understand the mechanism by which miR-325 affects circadian rhythms in neonates with HIBD,we compared clinical samples from neonates with HIBD and samples from healthy neonates recruited from the First Affiliated Hospital of Soochow University(Dushuhu Branch)in 2019.We found that circulating miR-325 levels correlated positively with the severity of sleep and circadian rhythm disorders in neonates with HIBD.Furthermore,a luciferase reporter gene assay revealed that LIM homeobox 3(LHX3)is a novel downstream target of miR-325.In addition,in miR-325 knock-down mice,the transcription factor LHX3 exhibited an miR-325-dependent circadian pattern of expression in the pineal gland.We established a neonatal mouse model of HIBD by performing doublelayer ligation of the left common carotid artery and exposing the pups to a low-oxygen environment for 2 hours.Lhx3 mRNA expression was significantly down-regulated in these mice and partially rescued in miR-325 knockout mice subjected to the same conditions.Finally,we showed that improvement in circadian rhythm-related behaviors in animals with HIBD was dependent on both miR-325 and LHX3.Taken together,our findings suggest that the miR-325-LHX3 axis is responsible for regulating circadian rhythms and provide novel insights into the identification of potential therapeutic targets for circadian rhythm disorders in patients with neonatal HIBD.The clinical trial was approved by Institutional Review Board of Children’s Hospital of Soochow University(approval No.2015028)on July 20,2015.Animal experiments were approved by Animal Care and Use Committee,School of Medicine,Soochow University,China(approval No.XD-2016-1)on January 15,2016.

Effects of ephedrine on expression of Nogo-A and synaptophysin in neonatal rats following hypoxic-ischemic brain damage

BACKGROUND： Central nervous system axons regenerate poorly following neonatal hypoxic-ischemic brain damage （HIBD）, partly due to inhibitors, such as Nogo-A. Very few studies have addressed the regulation of Nogo-A in neonatal rats following HIBD. However, numerous studies have shown that ephedrine accelerates neuronal remodeling and promotes recovery of neural function in neonatal rats following HIBD. OBJECTIVE： To investigate the effects of ephedrine on expression of Nogo-A and synaptophysin in brain tissues of neonatal rats following HIBD. DESIGN, TIME AND SETTING： A completely randomized, controlled study was performed at the Immunohistochemistry Laboratory of the Research Institute of Pediatrics, Children＇s Hospital of Chongqing Medical University from August 2008 to March 2009. MATERIALS： Ephedrine hydrochloride （Chifeng Pharmaceutical Group, China）, rabbit anti-Nogo-A polyclonal antibody （Abcam, UK）, and rabbit anti-synaptophysin polyclonal antibody （Lab Vision, USA） were used in this study. METHODS： A total of 96 healthy, neonatal, Sprague Dawley rats were randomly assigned to three groups （n = 32）： sham operation, HIBD, and ephedrine. The HIBD model was established by permanent occlusion of the left common carotid artery, followed by 2 hours of hypoxia （8% oxygen and 92% nitrogen）. In the sham operation group, the left common carotid artery was exposed, but was not ligated or subjected to hypoxia. Rats in the ephedrine group were intraperitoneally injected with ephedrine immediately following HIBD, with 1.5 mg/kg each time. Rats in the sham operation and HIBD groups were injected with an equal volume of saline. All neonatal rats were treated once daily for 7 days. MAIN OUTCOME MEASURES： Histopathological damage to the cortex and hippocampus was determined by hematoxylin-eosin staining. Expression of Nogo-A and synaptophysin was detected using immunohistochemical staining. RESULTS： Neuronal degeneration and edema were observed in the hypoxJc-Jschemic cortex and hippocampus by hematoxylin-eosin staining. Compared with the sham operation group, the levels of Nogo-A significantly increased in the HIBD group at various time points （P 〈 0.01）. Nogo-A expression was significantly reduced in the ephedrine group compared with the HIBD group （P 〈 0.01）. Synaptophysin expression was significantly decreased in the hypoxic-ischemJc cortex, compared with the sham operation group （P 〈 0.01）. Synaptophysin levels were significantly increased in the ephedrine group, compared with the HIBD group （P 〈 0.01）. CONCLUSION： Altered Nogo-A expression was associated with inversely altered synaptophysin expression. The use of ephedrine normalized expression levels of Nogo-A and synaptophysin following HIBD.

STUDY ON LIQUID-LIQUID EXTRACTION OF RESVERATROL FROM GIANT KNOTWEED AND ITS PROTECTIVE EFFECT ON MYOCARDIUM INJURY

Objective An efficient extraction and separation method of resveratrol from a Chinese herb giant knotweed was developed and the protective effect of resveratrol on myocardium injury was investigated.Methods An orthogonal experiment was utilized to optimize the extraction conditions and the pure white crystal obtained utilizing the proposed method was used for the investigation of myocardium ischemic injury.Results Resveratrol was found to have many beneficial activities including the protective effect on the heart and the scavenging of free radical.Conclusion The protective effect of resveratrol on myocardium injury is related to the quenching of lipid peroxidation.

AD-16 Protects Against Hypoxic-Ischemic Brain Injury by Inhibiting Neuroinflammation

Neuroinflammation is a key contributor to the pathogenic cascades induced by hypoxic-ischemic(HI)insult in the neonatal brain.AD-16 is a novel anti-inflammatory compound,recently found to exert potent inhibition of the lipopolysaccharide-induced production of pro-inflammatory and neurotoxic mediators.In this study,we evaluated the effect of AD-16 on primary astrocytes and neurons under oxygen-glucose deprivation(OGD)in vitro and in mice with neonatal HI brain injury in vivo.We demonstrated that AD-16 protected against OGD-induced astrocytic and neuronal cell injury.Single dose post-treatment with AD-16(1 mg/kg)improved the neurobehavioral outcome and reduced the infarct volume with a therapeutic window of up to 6 h.Chronic administration reduced the mortality rate and preserved whole-brain morphology following neonatal HI.The in vitro and in vivo effects suggest that AD-16 offers promising therapeutic efficacy in attenuating the progression of HI brain injury and protecting against the associated mortality and morbidity.

Time-dependent effect of combination therapy with erythropoietin and granulocyte colony-stimulating factor in a mouse model of hypoxic-ischemic brain injury

Erythropoietin （EPO） and granulocyte colony- stimulating factor （G-CSF） are likely to play broad roles in the brain. We investigated the effects of combination therapy with EPO and G-CSF in hypoxic- ischemic brain injury during the acute, subacute, and chronic phases. A total of 79 C57BL/6 mice with hypoxic-ischemic brain injury were randomly assigned acute （days 1-5）, subacute （days 11-15）and chronic （days 28-32） groups. All of them were treated with G-CSF （250 μg/kg） and EPO （5 000 U/kg） or saline daily for 5 consecutive days. Behavioral assessments and immunohistochemistry for angiogenesis, neuro- genesis, and astrogliosis were performed with an 8-week follow-up. Hypoxia-inducible factor-1 （HIF-1） was also measured by Western blot analysis. The results showed that the combination therapy with EPO and G-CSF in the acute phase significantly improved rotarod performance and forelimb-use symmetry compared to the other groups, while subacute EPO and G-CSF therapy exhibited a modest improvement compared with the chronic saline controls. The acute treatment significantly increased the density of CD31^＋（PECAM-1） and a-smooth muscle actin^＋ vessels in the frontal cortex and striatum, increased BrdU^＋/PSA- NCAM^＋ neurogenesis in the subventricular zone, and decreased astroglial density in the striatum. Furthermore, acute treatment significantly increased the HIF-1 expression in the cytosol and nucleus, whereas chronic treatment did not change the HIF-1 expression, consistent with the behavioral outcomes. These results indicate that the induction of HIF-1 expression by combination therapy with EPO and G-CSF synergistically enhances not only behavioral function but also neurogenesis and angiogenesis while decreasing the astroglial response in a time- dependent manner.

Brain metabolism in patients with vegetative state after post-resuscitated hypoxic-ischemic brain injury： statistical parametric mapping analysis of F-18 fluorodeoxyglucose positron emission tomography

Background Hypoxic-ischemic brain injury （HIBI） after cardiopulmonary resuscitation is one of the most devastating neurological conditions that causing the impaired consciousness. However, there were few studies investigated the changes of brain metabolism in patients with vegetative state （VS） after post-resuscitated HIBI. This study aimed to analyze the change of overall brain metabolism and elucidated the brain area correlated with the level of consciousness （LOC） in patients with VS after post-resuscitated HIBI. Methods We consecutively enrolled 17 patients with VS after HIBI, who experienced cardiopulmonary resuscitation. Overall brain metabolism was measured by F-18 fluorodeoxyglucose positron emission tomography （F-18 FDG PET） and we compared regional brain metabolic patterns from 17 patients with those from 15 normal controls using voxel-by-voxel based statistical parametric mapping analysis. Additionally, we correlated the LOC measured by the JFK-coma recovery scale-revised of each patient with brain metabolism by covariance analysis. Results Compared with normal controls, the patients with VS after post-resuscitated HIBI revealed significantly decreased brain metabolism in bilateral precuneus, bilateral posterior cingulate gyrus, bilateral middle frontal gyri, bilateral superior parietal gyri, bilateral middle occipital gyri, bilateral precentral gyri （PFEw correctecd 〈0.0001 ）, and increased brain metabolism in bilateral insula, bilateral cerebella, and the brainstem （PFEWcorrectecd 〈0.0001 ）. In covariance analysis, the LOC was significantly correlated with brain metabolism in bilateral fusiform and superior temporal gyri （P uncorrected 〈0.005）. Conclusions Our study demonstrated that the precuneus, the posterior cingulate area and the frontoparietal cortex, which is a component of neural correlate for consciousness, may be relevant structure for impaired consciousness in patient with VS after post-resuscitated HIBI. In post-resuscitated HIBI, measurement of brain metabolism using PET images may be helpful for investigating the brain function that cannot be obtained by morphological imaging and can be used to assess the brain area responsible for consciousness.

Biomarkers of hypoxic-ischemic encephalopathy:a systematic review

Background Current diagnostic criteria for hypoxic–ischemic encephalopathy in the early hours lack objective measurement tools.Therefore,this systematic review aims to identify putative molecules that can be used in diagnosis in daily clinical practice(PROSPERO ID:CRD42021272610).Data sources Searches were performed in PubMed,Web of Science,and Science Direct databases until November 2020.English original papers analyzing samples from newborns>36 weeks that met at least two American College of Obstetricians and Gynecologists diagnostic criteria and/or imaging evidence of cerebral damage were included.Bias was assessed by the Newcastle–Ottawa Scale.The search and data extraction were verified by two authors separately.Results From 373 papers,30 met the inclusion criteria.Data from samples collected in the first 72 hours were extracted,and increased serum levels of neuron-specific enolase and S100-calcium-binding protein-B were associated with a worse prognosis in newborns that suffered an episode of perinatal asphyxia.In addition,the levels of glial fibrillary acidic protein,ubiquitin carboxyl terminal hydrolase isozyme-L1,glutamic pyruvic transaminase-2,lactate,and glucose were elevated in newborns diagnosed with hypoxic–ischemic encephalopathy.Moreover,pathway analysis revealed insulin-like growth factor signaling and alanine,aspartate and glutamate metabolism to be involved in the early molecular response to insult.Conclusions Neuron-specific enolase and S100-calcium-binding protein-B are potential biomarkers,since they are correlated with an unfavorable outcome of hypoxic-ischemic encephalopathy newborns.However,more studies are required to determine the sensitivity and specificity of this approach to be validated for clinical practice.

Protective effects of erythropoietin pretreatment on myocardium with hypoxia/reoxygenation injury in rats

Objective: To establish the rat model with myocardial hypoxia/reoxygenation (H/R) injury, and investigate the protective effect of EPO pretreatment on the myocardium. Methods: Sixty male adult Wistar rats were randomly divided into 3 groups: control group, H/R group, and EPO group, 20 in each group. The rats in EPO group accepted injection of 5 000 U/kg recombinant human erythropoietin (RHuEPO) through vein, and the other rats accepted the injection of the same volume of saline. Twenty-four hours after the injection, rats in the EPO and H/R groups were put into the hypoxia environment for 12 h and then returned to the normoxic environment for 2 h, and then the samples of blood and myocardium were collected. Serum myocardial enzyme activity, apoptosis, ultrastructure, myocardial MDA contents, EPO receptor (EPOR) expression in cardiac myocytes and cardiac functions were tested. Results: EPOR expression was positive in cardiac myocytes of adult rat according to the result of immunonistochemitry assaying. Compared to those in H/R group, rats in EPO group presented lighter injury of myocardial ultrastructure, the reduction of serum myocardial enzyme activity, inhibition of apoptosis, the better recovery of cardiac functions, and the less production of oxygen-derived free radicals. Conclusion: Adult rat cardiac myocytes could express EPOR, and EPO pretreatment produced protective effects on myocardium with H/R injury.

Reperfusion after hypoxia-ischemia exacerbates brain injury with compensatory activation of the antiferroptosis system:based on a novel rat model

Hypoxic-ischemic encephalopathy,which predisposes to neonatal death and neurological sequelae,has a high morbidity,but there is still a lack of effective prevention and treatment in clinical practice.To better understand the pathophysiological mechanism underlying hypoxic-ischemic encephalopathy,in this study we compared hypoxic-ischemic reperfusion brain injury and simple hypoxic-ischemic brain injury in neonatal rats.First,based on the conventional RiceVannucci model of hypoxic-ischemic encephalopathy,we established a rat model of hypoxic-ischemic reperfusion brain injury by creating a common carotid artery muscle bridge.Then we performed tandem mass tag-based proteomic analysis to identify differentially expressed proteins between the hypoxic-ischemic reperfusion brain injury model and the conventional Rice-Vannucci model and found that the majority were mitochondrial proteins.We also performed transmission electron microscopy and found typical characteristics of ferroptosis,including mitochondrial shrinkage,ruptured mitochondrial membranes,and reduced or absent mitochondrial cristae.Further,both rat models showed high levels of glial fibrillary acidic protein and low levels of myelin basic protein,which are biological indicators of hypoxic-ischemic brain injury and indicate similar degrees of damage.Finally,we found that ferroptosis-related Ferritin(Fth1)and glutathione peroxidase 4 were expressed at higher levels in the brain tissue of rats with hypoxic-ischemic reperfusion brain injury than in rats with simple hypoxic-ischemic brain injury.Based on these results,it appears that the rat model of hypoxic-ischemic reperfusion brain injury is more closely related to the pathophysiology of clinical reperfusion.Reperfusion not only aggravates hypoxic-ischemic brain injury but also activates the anti-ferroptosis system.

Dephosphorylation of cardiomyocyte Cx43 is associated with myocardial ischemia and reperfusion injury

Objective：Myocardial ischemia/reperfusion（I/R） injury is the leading cause of death in the world. However, the details of the mechanism of its pathophysiology are still unknown. The present study was designed to investigate the role of connexin 43（Cx43） in acute models of myocardial I/R injury. Methods： Male C57BL/6 mice were subjected to myocardial ischemia（45 min） followed by reperfusion（4 hrs） in vivo. The whole operation was monitored using a two-lead ECG. Hearts were harvested and the level of protein was assessed by western blot analysis. Haematoxylin and Eosin（HE） staining was used to detect the extent of neutrophil infiltration. The expression level of IL-6 was detected by ELISA. Results： A murine myocardial I/R injury model was constructed successfully. Phosphorylated Cx43 decreased 83. 45% while non-phosphorylated Cx43 increased 1.62- fold in the myocardium after I/R injury. Neutrophil infiltration and the expression of the inflammatory cytokine IL-6 increased in the myocardium following I/R. Conclusion： During myocardial I/R injury, cardiomyocyte Cx43 is dephosphorylated, and this may be associated with an inflammatory response.

Protective mechanisms of micro RNA-27a against oxygen-glucose deprivation-induced injuries in hippocampal neurons

Hypoxic injuries during fetal distress have been shown to cause reduced expression of micro RNA-27a（mi R-27a）,which regulates sensitivity of cortical neurons to apoptosis.We hypothesized that miR-27 a overexpression attenuates hypoxia- and ischemia-induced neuronal apoptosis by regulating FOXO1,an important transcription factor for regulating the oxidative stress response.miR-27 a mimic was transfected into hippocampal neurons to overexpress miR-27 a.Results showed increased hippocampal neuronal viability and decreased caspase-3 expression.The luciferase reporter gene system demonstrated that mi R-27 a directly binded to FOXO1 3′UTR in hippocampal neurons and inhibited FOXO1 expression,suggesting that FOXO1 was the target gene for mi R-27 a.These findings confirm that mi R-27 a protects hippocampal neurons against oxygen-glucose deprivation-induced injuries.The mechanism might be mediated by modulation of FOXO1 and apoptosis-related gene caspase-3 expression.

Reperfusion injury components and manifestations determined by cardiovascular MR and MDCT imaging

Advances in magnetic resonance(MR) and computed tomography(CT) imaging have improved visualization of acute and scar infarct.Over the past decade,there have been and continues to be many significant technical advancements in cardiac MR and multi-detector computed tomography(MDCT) technologies.The strength of MR imaging relies on a variety of pulse sequences and the ability to noninvasively provide information on myocardial structure,function and perfusion in a single imaging session.The recent technical developments may also allow CT technologies to rise to the forefront for evaluating clinical ischemic heart disease.Components of reperfusion injury including myocardial edema,hemorrhage,calcium deposition and microvascular obstruction(MO) have been demonstrated using MR and CT technologies.MR imaging can be used serially and noninvasively in assessing acute and chronic consequences of reperfusion injury because there is no radiation exposure or administration of radioactive materials.MDCT is better suited for assessing coronary artery stenosis and as an alternative technique for as-sessing viability in patients where MR imaging is contraindicated.Changes in left ventricular(LV) volumes and function measured on cine MR are directly related to infarct size measured on delayed contrast enhanced images.Recent MR studies found that transmural infarct,MO and peri-infarct zone are excellent predictors of poor post-infarct recovery and mortality.Recent MR studies provided ample evidence that growth factor genes and stem cells delivered locally have beneficial effects on myocardial viability,perfusion and function.The significance of deposited calcium in acute infarct detected on MDCT requires further studies.Cardiac MR and MDCT imaging have the potential for assessing reperfusion injury components and manifestations.

Dynamic changes of myocardial nitric oxide formation and cGMP content in the early stage after radiation, burn and combined radiation-burninjuries in rats

Nitric oxide formation and cyclic GMP level in the myocardium were studied in the early stage after radiation, bum andcombined radiation-bum injuries in rats. Nitric oxide synthase (NOS) activity was measured in the cytosol of the left ventricularwall. In the controls, the cytosol was found to contain mainly Ca2+ -dependent NOS (cNOS) and a small amount of Ca2+ -inden-pendent NOS (iNOS). After burn and combined radiation-burn injuries, a marked increase of iNOS activity with a peak in the 8thhour postinjury was found but the myocardial cNOS activity declined obviously. Parallel to iNOS activity increase, there was a significant increase of myocardial production of NO and cGMP. The combined effcts of radiation and burn injuries on the rats weremore severe than those of burn injury alone. All the changes could be prevented by the administration of dexamethasone. No obvious changes were observed in the rats after radiation injury alone. Since the increase of cGMP level in the heart is associated withreduced contractility, it is possible that the increased production of NO stimulated by iNOS accounts at least partially, for the depression of myocardial contractility after bum and combined radiation burn injury.

miR-155-5p通过调控心肌细胞焦亡对大鼠心肌缺血-再灌注损伤的影响及机制研究

目的探讨微小RNA(miR)-155-5p对心肌缺血-再灌注损伤(IRI)大鼠心肌细胞焦亡的影响及机制。方法60只SD大鼠随机分为假手术(sham)组、IRI组、agomir-NC组、miR-155-5p agomir组、antagomir-NC组和miR-155-5p antagomir组,每组10只。采用超声心动图仪测定大鼠左心室舒张末期内径(LVEDD)、左心室收缩末期内径(LVESD)、左心室射血分数(LVEF)和左心室短轴缩短率(LVFS)。酶联免疫吸附试验检测大鼠血清肌酸激酶同工酶(CK-MB)、乳酸脱氢酶(LDH)和心肌肌钙蛋白T(cTnT)水平,心肌组织白细胞介素(IL)-1β、IL-6、IL-18和肿瘤坏死因子(TNF)-α水平;苏木素-伊红染色观察大鼠心肌组织病理学变化;实时荧光定量聚合酶链反应检测大鼠心肌组织miR-155-5p和沉默信息调节因子1(SIRT1)信使RNA(mRNA)表达水平;双荧光素酶报告基因实验验证miR-155-5p与SIRT1的靶向关系;蛋白质印迹法检测大鼠心肌组织SIRT1、NOD样受体蛋白3(NLRP3)、剪切型半胱氨酸天冬氨酸蛋白水解酶-1(Cleaved Caspase-1)和GSDMD蛋白表达水平。结果与sham组比较,IRI组大鼠LVEDD和LVESD升高,LVEF和LVFS降低,血清CK-MB、LDH和cTnT水平升高,心肌组织IL-1β、IL-6、IL-18、TNF-α水平升高,心肌组织结构破坏严重,心肌纤维排列紊乱,NLRP3、Cleaved Caspase-1和GSDMD蛋白相对表达量升高,SIRT1蛋白相对表达量降低(均为P<0.05/5)。与IRI组比较,miR-155-5p agomir组大鼠LVEDD和LVESD升高,LVEF和LVFS降低,血清CK-MB、LDH和cTnT水平升高,心肌组织中IL-1β、IL-6、IL-18、TNF-α水平升高,心肌组织病变程度加重,NLRP3、Cleaved Caspase-1和GSDMD蛋白相对表达量升高,SIRT1蛋白相对表达量降低;miR-155-5pantagomir组大鼠LVEDD和LVESD降低,LVEF和LVFS升高,血清CK-MB、LDH和cTnT水平降低,心肌组织中IL-1β、IL-6、IL-18、TNF-α水平降低,心肌组织病变程度减轻,NLRP3、Cleaved Caspase-1和GSDMD蛋白相对表达量下降,SIRT1蛋白相对表达量升高(均为P<0.05/5)。miR-155-5p与SIRT1在大鼠心肌组织中的表达水平呈负相关,且SIRT1是miR-155-5p的靶基因。结论miR-155-5p可能通过靶向下调SIRT1促进NLRP3介导的心肌细胞焦亡参与调节大鼠心肌IRI。