Hypoxic Injury Research Articles

Early Detection of High-altitude Hypoxic Brain Injury by In Vivo Electrochemistry.

High-altitude hypoxic brain injury (HHBI) is a kind of acute mountain sickness and the survival rate of patients with HHBI can be improved only if it is detected and treated at the early stage. However, limited by speediness and accuracy, it is still very difficult for most of current approaches to realize the early detection of HHBI. We propose herein a novel strategy for this goal based on spatiotemporal changes in the brain oxygen level. As revealed by in vivo electrochemistry, the characteristic changes of brain oxygen level under the high-altitude exposure are directly associated with the brain hypoxia status. Given brain hypoxia is the main pathogenesis of HHBI, the degree of HHBI can be diagnosed by the variation of brain oxygen, making the early detection of HHBI feasible. In addition, the risk of HHBI for mouse exposed to high-altitude hypoxia environments can be also prognosed days in advance.

Early Detection of High‐altitude Hypoxic Brain Injury by In Vivo Electrochemistry

High‐altitude hypoxic brain injury (HHBI) is a kind of acute mountain sickness and the survival rate of patients with HHBI can be improved only if it is detected and treated at the early stage. However, limited by speediness and accuracy, it is still very difficult for most of current approaches to realize the early detection of HHBI. We propose herein a novel strategy for this goal based on spatiotemporal changes in the brain oxygen level. As revealed by in vivo electrochemistry, the characteristic changes of brain oxygen level under the high‐altitude exposure are directly associated with the brain hypoxia status. Given brain hypoxia is the main pathogenesis of HHBI, the degree of HHBI can be diagnosed by the variation of brain oxygen, making the early detection of HHBI feasible. In addition, the risk of HHBI for mouse exposed to high‐altitude hypoxia environments can be also prognosed days in advance.

Retraction Note: Knockdown of insulin-like growth factor 1 exerts a protective effect on hypoxic injury of aged BM-MSCs: role of autophagy.

Retraction Note: Knockdown of insulin-like growth factor 1 exerts a protective effect on hypoxic injury of aged BM-MSCs: role of autophagy.

Integration of transcriptomics and metabolomics to study the mechanism of Siwei Huangqi powder in Tibetan medicine for protecting against high-altitude hypoxic brain injuries

Integration of transcriptomics and metabolomics to study the mechanism of Siwei Huangqi powder in Tibetan medicine for protecting against high-altitude hypoxic brain injuries

The antisickling agent, 5-hydroxymethyl-2-furfural: Other potential pharmacological applications.

For the last two decades, the aromatic aldehyde 5-hydroxymethyl-furfural (5-HMF) has been the subject of several investigations for its pharmacologic potential. In 2004, the Safo group reported that 5-HMF has potent antisickling activity by targeting and ameliorating the primary pathophysiology of hypoxia-induced sickling of erythrocytes (red blood cells [RBC]). Following the encouraging outcome of the preclinical and phase I/II clinical studies of 5-HMF for the treatment of sickle cell disease (SCD), there have been multiple studies suggesting 5-HMF has several other biological or pharmacologic activities, including anti-allergic, antioxidant, anti-hypoxic, anti-ischemic, cognitive improvement, anti-tyrosinase, anti-proliferation, cytoprotective, and anti-inflammatory activities. The wide range of its effects makes 5-HMF a potential candidate for treating a variety of diseases including cognitive disorders, gout, allergic disorders, anemia, hypoxia, cancers, ischemia, hemorrhagic shock, liver fibrosis, and oxidative injury. Several of these therapeutic claims are currently under investigation and, while promising, vary in terms of the strength of their evidence. This review presents the research regarding the therapeutic potential of 5-HMF in addition to its sources, physicochemical properties, safety, absorption, distribution, metabolism, and excretion (ADME) profiles.

Evaluation of Neutrophil Gelatinase-Associated Lipocalin Levels in Children With Febrile Seizures: A Case-Control Study.

Febrile seizure (FS) is a common pediatric neurological disorder, which may be associated with hypoxia and kidney injury. We aimed to investigate serum levels of neutrophil gelatinase-associated lipocalin (NGAL) in children with FS. This case-control study included 50 children with FS, 50 febrile controls (FCs), and 50 healthy controls (HCs). We measured serum NGAL levels using a human enzyme-linked immunosorbent assay. Serum NGAL/creatinine values showed significant differences within and between study groups with the highest levels for the FS group (1382 ± 215), the middle for FCs (1133 ± 129), and the lowest for HCs (857 ± 97). None of the study participants had abnormal serum creatinine levels, and their values were comparable among the 3 study groups. In conclusion, children with FS may have increased serum NGAL levels despite normal serum creatinine, indicating that FS could contribute to subclinical renal injury without significant loss of excretory kidney function.

Effect of nelonemdaz for patients with out-of-hospital cardiac arrest: the AWAKE phase II randomised clinical trial

Abstract Background Hypoxic brain injury is a major hurdle that limits the survival of out-of-hospital cardiac arrest (OHCA). Nelonemdaz is a dual-target neuroprotectant, serving as a moderate NR2B-selective N-methyl-D-aspartate (NMDA) receptor antagonist while also exhibiting potent free radical scavenger properties. This dual neuroprotective action of nelonemdaz has the potential to reduce hypoxic brain injury in OHCA. We investigated the efficacy and safety of nelonemdaz for patients with OHCA. Methods AWAKE trial was a double-blind, placebo-controlled, randomised, multicentre phase II trial at 5 sites in South Korea. OHCA patients undergoing targeted temperature management were randomly assigned to high-dose (5250 mg), low-dose (3250 mg), and placebo groups at a 1:1:1 ratio. The primary outcome was the blood level of neuron-specific enolase (NSE) after 4th administration of drug. Secondary outcomes comprised blood biomarkers including neuron specific enolase (NSE) and S100beta, brain magnetic resonance imaging (MRI), and Cerebral Performance Category (CPC) and Modified Rankin Scale (mRS) up to day 90. Safety is assessed by serious adverse event. Findings: A total of 105 patients were enrolled between November 18, 2018 to February 23, 2023. Patients with a median age of 61 years and 82% male were assigned to the high-dose (N=37), low-dose (N=35), and placebo (N=33) groups. Primary outcome was evaluated in 93 patients. There was no difference of neuron specific enolase (NSE, ng/mL), which served as the primary endpoint, between high-dose (median and interquartile range; 23·7, 15·0–69·9) and placebo (17·5, 13·6–113·0) groups and also between low-dose (26·6, 16·2–83·4) versus placebo groups (all p>0·05). Among secondary outcomes, fractional anisotropy of brain MRI was significantly higher in high-dose group compared to placebo group (0·465, 0·449–0·485 versus 0·441, 0·431–0·464; p=0·028), and was not different between low-dose (0·462, 0·439–0·480) and placebo groups (p>0·05). At day 90, the common odds ratio (95% confidence interval) indicating a favourable shift in the modified Rankin Scale was 1·25 (0·48–3·24) and 1·22 (0·47–3·20) in the high-dose and low-dose groups respectively, compared to placebo group (all p>0·05). No serious adverse events were reported. Interpretation: Nelonemdaz did not reduced blood NSE level of OHCA patients. However, patients treated with high-dose nelonemdaz showed better fractional anisotropy that suggests reduced cerebral white matter damage. Patients treated with nelonemdaz also showed a favourable tendency of neurological recovery at day 90 without significant adverse effects. These results justify the initiation of a large-scale phase III trial.Neurological function up to day 90

The role of TRAP1 in regulating mitochondrial dynamics during acute hypoxia-induced brain injury

Brain damage caused by acute hypoxia is associated with the physiological activities of mitochondria. Although mitochondria being dynamically regulated, our comprehensive understanding of the response of specific brain cell types to acute hypoxia remains ambiguous. Tumor necrosis factor receptor-associated protein 1 (TRAP1), a mitochondrial-based molecular chaperone, plays a role in controlling mitochondrial movements. Herein, we demonstrated that acute hypoxia significantly alters mitochondria morphology and functionality in both in vivo and in vitro brain injury experiments. Summary-data-based Mendelian Randomization (SMR) analyses revealed possible causative links between mitochondria-related genes and hypoxia injury. Advancing the protein-protein interaction network and molecular docking further elucidated the associations between TRAP1 and mitochondrial dynamics. Furthermore, it was shown that TRAP1 knockdown levels variably affected the expression of key mitochondrial dynamics proteins (DRP1, FIS1, and MFN1/2) in primary hippocampal neurons, astrocytes, and BV-2 cell, leading to changes in mitochondrial structure and function. Understanding the function of TRAP1 in altering mitochondrial physiological activity during hypoxia-induced acute brain injury could help serve as a potential therapeutic target to mitigate neurological damage.

Clinical and Radiological Parameters Affecting the Yield of Routine Electroencephalography in Various Indications.

To highlight the significance of various clinical and radiological parameters in association with specific electroencephalographic (EEG) patterns in order to prioritize EEG referrals. This retrospective, cross-sectional study was conducted in the neurology department of King Fahad University Hospital, Alkhobar, and involved a review and analysis of EEG and medical records pertaining to 604 patients referred for routine EEG. The data were analyzed using SPSS version 22. An association between various parameters and EEG yield was established. Factors associated with the yield of abnormal EEG patterns were diverse, like generalized tonic-clonic seizures (GTCs) (P =.05), status epilepticus (SE) (P =.05), altered level of consciousness (ALC) (P =.00), abnormal movement (P =.00), cardiac arrest (P =.00), prior history of epilepsy (P =.04), chronic renal disease (CRD) (P =.03), abnormal neurological exam (P =.00), and cortical lesions on brain imaging (P =.00). Among the abnormal EEG patterns, epileptiform activity (EA) in EEG was associated with focal seizures (P =.03), GTCs (P =.00), falls (P =.05), cardiac arrest (P =.00), a history of epilepsy (P =.00), and hypoxic ischemic injury (P =.03). Encephalopathy in EEG was also associated with focal sz (P =.02), GTCs (P =.00), SE (P =.01), ALC (P =.00), cardiac arrest (P =.00), history of stroke (P =.01), and epilepsy (P =.00). Among the studied parameters, patient level of consciousness, neurological exam findings, and neuroimaging findings, with some discrepancies, were found to be the most consistent in predicting the EEG yield. The study demonstrated the value of a proper neurological exam and careful selection of patients to gain the optimum benefit from the routine EEG.

Curcumin triggers the Wnt/β-catenin pathway and shields neurons from injury caused by intermittent hypoxia

The objective of this study was to explore the molecular basis through which Curcumin (Cur) mitigates neuronal damage caused by obstructive sleep apnea (OSA). HT22 was used to simulate intermittent hypoxia (IH) injury and explore the effect of Cur on these cells. We evaluated the cell viability, cytotoxicity, apoptosis, proliferation, and Wnt/β-catenin (WβC) pathway. IWR-1 was used to block the pathway and investigate the protective mechanism of Cur. We constructed an in vivo model of IH to validate the results of the cellular experiments. IH accelerated apoptosis and cytotoxicity, suppressed proliferation, and decreased the activity of the WβC pathway. Cur can significantly improve cell viability, reduce apoptosis rate and cell toxicity, promote cell proliferation, and up-regulate the WβC. After blocking the WβC pathway, the proliferative effect of Cur was observably weakened. In vivo, IH caused hippocampal damage and inhibited WβC pathway activity in mice, which was ameliorated by Cur treatment. This implies that Cur could be a novel treatment option for neurological impairment brought on by OSA.

Tranexamic Acid for reduction of intra- and postoperative TRansfusion requirements in elective Abdominal surgery (TATRA): study protocol for an investigator-initiated, multicenter, double-blind, placebo-controlled, randomized superiority trial with two parallel groups

BackgroundIntra- and postoperative hemorrhage is a relevant problem in major abdominal surgery, leading to acute anemia and necessitating transfusion of packed red blood cells. It is estimated that in 30% of abdominal surgeries, intra- or postoperative transfusion is required. Transfusion potentially has detrimental health effects and poses a considerable socioeconomic burden. Tranexamic acid, a lysine analog inhibiting plasminogen activation and providing clot stability, has been used to reduce hemorrhage. While there is ample evidence in other surgical disciplines, it is almost completely lacking in abdominal surgery.MethodsThis multicenter double-blind parallel group randomized superiority trial will compare tranexamic acid (loading dose 1000 mg over 10 min prior to skin incision, maintenance dose 125 mg/h continuously until skin closure or until 1000 mg have been administered) to placebo in patients ≥ 18 years undergoing elective esophagectomy, gastrectomy, colectomy, rectal resection, pancreatic resection, or hepatectomy. The primary efficacy endpoint is the intra- or postoperative transfusion of at least one unit of packed red blood cells. Key secondary endpoints are the number of transfused units per patient, estimated intraoperative blood loss, postoperative complications/mortality, length of hospital stay, operation/anesthesia time, D-dimer levels, and quality of life. Sample size calculation is based on the assumption that in the control group, 30% of patients require transfusion while the intervention achieves a risk reduction of 33%, reducing the probability to 20%. With a type one error of 5% and a power of 90%, using a two-sided χ2 test, this results in 412 patients per group. Accounting for non-compliance, 425 patients are to be randomized per group. The total trial duration will be 30 months with a recruitment period of 18 months.DiscussionIf the proposed trial yielded positive results, the routine use of tranexamic acid in major abdominal surgery would be supported. This would avoid acute anemia with detrimental effects such as tissue hypoxia and organ injury, as well as the negative immediate and delayed effects of transfusions.Trial registrationEU CT Nr: 2023–509970-43–01, NCT06414031. Registered on 10 May 2024.

Nitidine Chloride Alleviates Hypoxic Stress via PINK1-Parkin-Mediated Mitophagy in the Mammary Epithelial Cells of Milk Buffalo.

Hypoxia in the mammary gland epithelial cells of milk buffalo (BMECs) can affect milk yield and composition, and it can even cause metabolic diseases. Nitidine chloride (NC) is a natural alkaloid with antioxidant properties that can scavenge excessive reactive oxygen species (ROS). However, the effect of NC on the hypoxic injury of BMECs and its molecular mechanisms are still unknown. Here, an immunofluorescence assay, transmission electron microscopy (TEM), and flow cytometry, combined with untargeted metabolomics, were used to investigate the protective effect of NC on hypoxic stress injury in BMECs. It was found that NC can significantly reduce cell activity (p < 0.05) and inhibit cellular oxidative stress (p < 0.05) and cell apoptosis (p < 0.05). A significant decrease in mitophagy mediated by the PINK1-Parkin pathway was observed after NC pretreatment (p < 0.05). In addition, a metabolic pathway enrichment analysis demonstrated that the mechanisms of NC against hypoxic stress may be related to the downregulation of pathways involving aminoacyl tRNA biosynthesis; arginine and proline metabolism; glycine, serine, and threonine metabolism; phenylalanine, tyrosine, and tryptophan biosynthesis; and phenylalanine metabolism. Thus, NC has a protective effect on hypoxic mitochondria, and it can regulate amino acid metabolism in response to hypoxic stress. The present study provides a reference for the application of nitidine chloride to regulate the mammary lactation function of milk buffalo.

Olig2+/NG2+/BLBP+ astrocyte progenitors: a novel component of the neurovascular unit in the developing mouse hippocampus.

Astrocytes are key components of the neurovascular unit. While we have recently identified Olig2+ astrocyte progenitors (ASPs) in the developing mouse dentate gyrus (DG), their molecular signature remains incompletely characterized. Here we demonstrate that Olig2+ ASPs predominantly express brain lipid-binding protein (BLBP), while only a small population of them expresses gfap-GFP. These Olig2+/BLBP+ ASPs co-express the transcription factors Sox3, Sox9 and the proteoglycan NG2 but not Sox10, a marker for oligodendrocyte progenitors (OLPs). Olig2+ ASPs appear from embryonic day 18 (E18) onwards and decline at postnatal day 14 (P14). Consistent with the proliferation of both Olig2+ and NG2+ glial cells after brain injury, intrauterine intermittent hypoxia (IH) led to an increase in Olig2+/NG2+/BLBP+ ASPs in the postnatal DG. IH also promoted both angiogenesis and vascular coupling of Olig2+/NG2+ ASPs. Our data suggest that IH-induced expression of HIF1a increases Olig2+/NG2+/BLBP+ ASPs in a cell non-autonomous manner. Our data also revealed increased vascular coupling of GFAP+ astrocytes following IH, while the number of GFAP+ astrocytes remains unchanged. Given that BLBP, Olig2 and NG2 are expressed in reactive astrocytes, our findings suggest that Olig2+/NG2+/BLBP+ ASPs represent a subtype of reactive astrocyte progenitors. Furthermore, the enhanced vascular coupling of Olig2+/NG2+/BLBP+ ASPs appears to be an adaptive response to hypoxic brain injury. This study provides new insights into the molecular characteristics of Olig2+/NG2+/BLBP+ ASPs and their potential role in the brain's response to hypoxic injury, contributing to our understanding of neurovascular unit dynamics in both development and pathological conditions.

Riboflavin as a potential new therapeutic agent for perinatal encephalopathies caused by cerebral oxygen deprivation

ABSTRACT Objective: This letter to the editor presents suggestions for the therapeutic use of riboflavin in perinatal brain lesions caused by oxygen deprivation. Methods: Clinical and preclinical studies using riboflavin conjugated with other components for the treatment of cerebral oxygen deprivation were included in the discussion. Results: Oxygen deprivation is predisposed by anoxia, hypoxia, or ischemia and causes severe early central damage, including sensorimotor impairment. At the moment, these lesions lack effective and affordable therapies. We present studies demonstrating the neuroprotective effects of riboflavin–containing drugs to treat children affected by hypoxic perinatal injuries. Discussion: This article suggests conducting preclinical studies to elucidate the potential isolated effects of riboflavin on the pathogenesis of perinatal brain injury caused by oxygen deprivation, by presenting routes for future clinical strategies for the prevention or treatment of perinatal encephalopathies.

Inhibition of the FOXO1–ROCK1 axis mitigates cardiomyocyte injury under chronic hypoxia in Tetralogy of Fallot by maintaining mitochondrial quality control

IntroductionPersistent chronic myocardial hypoxia causes disturbances in mitochondrial quality control (MQC), ultimately leading to increased cardiomyocyte injury in patients with Tetralogy of Fallot (TOF). The present study aimed to identify the key effector molecules of cardiomyocyte injury under chronic hypoxia in TOF. MethodsClinical data from TOF patients were collected and whole transcriptome sequencing was performed on myocardial samples. Chronic hypoxia models were established in cardiac-specific knockout mice and cardiomyocytes, and a series of molecular experiments were used to determine the specific mechanisms involved. ResultsClinical cohort data and whole-transcriptome sequencing analysis of myocardial samples from TOF patients revealed that forkhead box O1 (FOXO1) plays an important role in chronic hypoxic cardiomyocyte injury. In a model of chronic hypoxia established in FOXO1 cardiac-specific knockout mice and FOXO1 gene-deficient cardiomyocytes, the AMPK signaling pathway regulates the expression of FOXO1, which in turn disrupts MQC by regulating the transcriptional activation of Rho-associated protein kinase 1 (ROCK1), and increasing the production of mitochondrial ROS, thereby exacerbating damage to cardiomyocytes. Excessive reactive oxygen species (ROS) production during MQC dysfunction further activates Cox7a2L to increase the assembly of the respiratory chain supercomplex. In addition, we found that miR-27b-3p partially binds to the 3′ untranslated region of FOXO1 to exert a protective effect. ConclusionsMaintenance of MQC under chronic hypoxia is achieved through a series of injury-protection mechanisms, suggesting that FOXO1 inhibition may be crucial for future mitigation of chronic hypoxic cardiomyocyte injury in TOF.

Sodium Hydrosulfide Protects Rats from Hypobaric-Hypoxia-Induced Acute Lung Injury

Hydrogen sulfide (H2S), as a key gas signaling molecule, plays an important role in regulating various diseases, with appropriate concentrations providing antioxidative, anti-inflammatory, and anti-apoptotic effects. The specific role of H2S in acute hypoxic injury remains to be clarified. This study focuses on the H2S donor sodium hydrosulfide (NaHS) and explores its protective effects and mechanisms against acute hypoxic lung injury. First, various mouse hypoxia models were established to evaluate H2S’s protection in hypoxia tolerance. Next, a rat model of acute lung injury (ALI) induced by hypoxia at 6500 m above sea level for 72 h was created to assess H2S’s protective effects and mechanisms. Evaluation metrics included blood gas analysis, blood routine indicators, lung water content, and lung tissue pathology. Additionally, LC-MS/MS and bioinformatic analyses were combined in performing quantitative proteomics on lung tissues from the normoxic control group, the hypoxia model group, and the hypoxia model group with NaHS treatment to preliminarily explore the protective mechanisms of H2S. Further, enzyme-linked immunosorbent assays (ELISA) were used to measure oxidative stress markers and inflammatory factors in rat lung tissues. Lastly, Western blot analysis was performed to detect Nrf2, HO-1, P-NF-κB, NF-κB, HIF-1α, Bcl-2, and Bax proteins in lung tissues. Results showed that H2S exhibited significant anti-hypoxic effects in various hypoxia models, effectively modulating blood gas and blood routine indicators in ALI rats, reducing pulmonary edema, improving lung tissue pathology, and alleviating oxidative stress, inflammatory responses, and apoptosis levels.

Salidroside improves blood-brain barrier integrity and cognitive function in hypobaric hypoxia mice by inhibiting microglia activation through GSK3β.

Salidroside, an active component found in Rhodiola rosea L., has emerged as a potential therapeutic agent for the prevention and treatment of hypoxic brain injury, while the precise target and mechanism of salidroside were remain unclear. The study utilized techniques such as network pharmacology, transcriptome sequencing to investigate the mechanism and target of salidroside in regulating blood-brain barrier (BBB) function to protect hypoxic brain injury in vivo. Utilized macromolecular docking and molecular biology techniques to explore the molecular mechanism of salidroside in alleviating brain injury induced by hypoxia in BV2 cell model. The results show that salidroside alleviated the learning and memory dysfunction and pathological injury in mice exposed to hypobaric hypoxia, reduced brain water content and attenuate the inflammatory response and oxidative stress, effectively reversed S100β in serum and promoted the repair of BBB. GSK3β is an important therapeutic target of salidroside in the treatment of hypoxic cognitive impairment, and salidroside can specifically bind GSK3β in the ATP binding pocket, inducing the phosphorylation of GSK3β, targeting downstream Nrf-2 to regulate microglia activity, promoting the accumulation of β-catenin, thereby inhibiting microglial activation, improving the BBB integrity injury and achieving a neuroprotective effect. This study demonstrates that salidroside can inhibit the activation of microglia by inducing GSK3β phosphorylation, achieve neuroprotective effects and alleviate learning and memory dysfunction in hypobaric hypoxia mice. This study provides a theoretical basis for the development of salidroside and the clinical application of Rhodiola rosea L.

Salidroside rescues hypoxic cardiomyocytes by regulating the EGLN1/HIF‑1α pathway.

Myocardial infarction is characterized by oxygen deficiency caused by arterial flow restriction. Salidroside (SAL) protects against myocardial damage via antioxidant production and inhibition of apoptosis. The present study aimed to investigate potential rescue mechanism of SAL on hypoxic cardiomyocytes. H9C2 cardiomyocytes were divided into normoxia, hypoxia and hypoxia + SAL groups. The inhibitory rate of hypoxia and the optimal concentration and rescue effect of SAL were determined using Cell Counting Kit-8 assay and flow cytometry. Ca2+ concentration following hypoxia treatment and SAL intervention were detected by Fluo-4/acetoxymethyl. Tandem mass tag (TMT) proteomics was used to analyze the differential expression of hypoxia-associated proteins among the three groups. SAL exerted a protective effect on hypoxia-injured cardiomyocytes by enhancing aerobic metabolism during hypoxia and rescuing cardiomyocytes from hypoxic damage. SAL promoted cell proliferation, decreased apoptosis and increased Ca2+ levels in cell membranes of hypoxic cardiomyocytes. TMT proteomics results showed that the expression levels of intracellular hypoxia inducible factor-1 (HIF)-1α and Egl-9 family HIF 1 (EGLN1) in H9C2 cells were elevated under hypoxic conditions. However, SAL significantly decreased expression levels of HIF-1α and EGLN1. SAL inhibited mitochondrial calcium overload in hypoxic cardiomyocytes and attenuated expression of hypoxia-associated factors. SAL exerted its rescue effect on hypoxic cardiomyocytes through the EGLN1/HIF-1α pathway, thereby suppressing cardiomyocyte apoptosis, improving mitochondrial energy metabolism efficiency and rescuing cardiomyocytes from hypoxic injury.

Validation of an ultrahigh contrast divided subtracted inversion recovery technique using a standard T1 phantom.

The divided subtracted inversion recovery (dSIR) is a high T1 contrast technique that shows changes in white matter in patients with traumatic brain injury and hypoxic injury. The changes can be explained by small differences in T1; however, to date, there has been no independent validation of the technique using a standard reference. The present study develops the theory of the dSIR signal and performs validation using the NIST/ISMRM T1 phantom. Non-idealities are explored, including the influence of noise bias and finite repetition time (TR), which leads to the introduction of an optimally efficient TR for inversion recovery acquisitions. Results show excellent agreement with theoretical calculations.

Decreased hepatic CT value on immediate postmortem CT after CPR: Comparison with antemortem CT and correlation with liver enzymes changes

Purpose We compared hepatic antemortem CT (AMCT) and postmortem CT (PMCT) values obtained in the same subjects. The correlations between the changes in hepatic CT values and changes in aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) values were also investigated.Materials and methods Fifty subjects (20 males, 30 females; mean age: 85.9 ± 7.9 years; range: 67–100 years) who were transported to the emergency room in cardiopulmonary arrest (CPA) and underwent PMCT immediately after unsuccessful cardiopulmonary resuscitation (CPR) comprised the study population. The hepatic AMCT and PMCT values were both measured, and the differences between the two were calculated. The differences between AST, ALT, and LDH values at CPR and antemortem were also calculated. The correlations between the hepatic CT value differences and AST, ALT, and LDH value differences also were assessed.Results The hepatic AMCT and PMCT values of 61.7 ± 6.8 Hounsfield Unit (HU) and 46.2 ± 8.2 HU, respectively, were significantly different. The AST, ALT, and LDH values were significantly higher at CPR than at antemortem. The differences in the hepatic CT values and in the AST, ALT, and LDH values were moderately correlated.Conclusion The hepatic values were significantly lower on PMCT than on AMCT. The changes in hepatic CT values correlated with the changes in the liver deviation enzyme values. These results indicate the possibility that ischemic, hypoxic injury, and anerobic glycolysis of the liver at CPR after CPA are the cause of decreased hepatic PMCT values.