Nicorandil Ameliorates Doxorubicin-Induced Cardiotoxicity in Rats, as Evaluated by 7 T Cardiovascular Magnetic Resonance Imaging.

PURPOSE: Doxorubicin-induced cardiotoxicity (DIC) is a common side effect of doxorubicin chemotherapy, and a major mechanism of DIC is inflammation. However, no effective method exists to prevent DIC. In the present study, we investigated the cardioprotective effects of nicorandil against DIC using multiparametric cardiac magnetic resonance (CMR) imaging and elucidated the anti-inflammatory properties of nicorandil in rat models. METHODS: Male Sprague-Dawley rats received four weekly intraperitoneal doxorubicin doses (4 mg/kg/injection) to establish the DIC model. After treatment with or without nicorandil (3 mg/kg/day) or diazoxide (10 mg/kg/day) orally, all the groups underwent weekly CMR examinations, including cardiac function and strain assessment and T2 mapping, for 6 weeks. Additionally, blood samples and hearts were collected to examine inflammation and histopathology. RESULTS: According to our results, the earliest DIC CMR parameter in the doxorubicin group was T2 mapping time prolongation compared with the DIC rats treated with nicorandil (doxorubicin+nicorandil group) at week 2. Subsequently, the left ventricular ejection fraction (LVEF) and global peak systolic myocardial strain in the doxorubicin group were significantly reduced, and nicorandil effectively inhibited these effects at week 6. Our results were confirmed by histopathological evaluations. Furthermore, nicorandil treatment had a protective effect against the doxorubicin-induced inflammatory response. Interestingly, similar protective results were obtained using the KATP channel opener diazoxide. CONCLUSION: Collectively, our findings indicate that nicorandil application ameliorates DIC in rats with significantly higher cardiac function and myocardial strain and less fibrosis, apoptosis and inflammatory cytokine production. Nicorandil prevents T2 abnormalities in the early stages of DIC, showing a high clinical value for early nicorandil treatment in chemotherapy patients.

Using 7.0 T cardiac magnetic resonance to investigate the effect of estradiol on biventricular structure and function of ovariectomized rats exposed to chronic hypobaric hypoxia at high altitude.

BACKGROUND: Despite that estradiol can reduce the risk of cardiovascular diseases in ovariectomized animals in the plains, its effect on animals at high altitude has seldom been reported. We hypothesize that estradiol can ameliorate cardiac damage to ovariectomized rats induced by chronic exposure to hypobaric hypoxia at high altitude. PURPOSE: This study was intended to investigate whether cardiovascular magnetic resonance (CMR) imaging could reveal cardioprotective effect of estradiol on ovariectomized rats under chronic exposure to hypobaric hypoxia at high altitude. METHODS: Thirty-two rats were randomized into the Control group (Plain), HH + Sham group (Hypobaric Hypoxia + Sham), HH + OVX group (Hypobaric Hypoxia + Bilateral Ovariectomy) and HH-OVX + E2 group (Hypobaric Hypoxia + Bilateral Ovariectomy + Estradiol, 50 µg/kg, 3 times a week, for 6 weeks) (n = 8 per group). Except the Control group (altitude: 500 m), rats in other groups were subcutaneously injected with 17ß -estradiol or vehicle and exposed to chronic hypobaric hypoxia in Qinghai-Tibet Plateau (altitude: 4250 m), China, for 6 weeks. Biventricular cardiac function and global strain of the rats were measured by CMR and analyzed using the cine tissue tracking techniques. Biochemical tests, histopathology and electronic microscopy were used to evaluate the protective effect of estradiol on the heart tissue of ovariectomized rats exposed to a high-altitude environment. RESULTS: The biventricular ejection fraction and global strains decreased in the HH + OVX group compared with that in the Control group (all p < 0.05). All the aforementioned changes in the HH + OVX group ameliorated in the HH-OVX + E2 group (all p < 0.05). Estradiol also alleviated the right ventricular dilatation and hypertrophy in the HH + OVX group (all p < 0.05). In addition, histological and biochemical analyses also supported these in vivo results. CONCLUSIONS: Estradiol ameliorated the biventricular structural and functional damage in ovariectomized rats exposed to chronic hypobaric hypoxia at high altitude.

A Multimodal MR Imaging Study of the Effect of Hippocampal Damage on Affective and Cognitive Functions in a Rat Model of Chronic Exposure to a Plateau Environment.

Prolonged exposure to high altitudes above 2500 m above sea level (a.s.l.) can cause cognitive and behavioral dysfunctions. Herein, we sought to investigate the effects of chronic exposure to plateau hypoxia on the hippocampus in a rat model by using voxel-based morphometry, creatine chemical exchange saturation transfer (CrCEST) and dynamic contrast-enhanced MR imaging techniques. 58 healthy 4-week-old male rats were randomized into plateau hypoxia rats (H group) as the experimental group and plain rats (P group) as the control group. H group rats were transported from Chengdu (500 m a.s.l.), a city in a plateau located in southwestern China, to the Qinghai-Tibet Plateau (4250 m a.s.l.), Yushu, China, and then fed for 8 months there, while P group rats were fed in Chengdu (500 m a.s.l.), China. After 8 months of exposure to plateau hypoxia, open-field and elevated plus maze tests revealed that the anxiety-like behavior of the H group rats was more serious than that of the P group rats, and the Morris water maze test revealed impaired spatial memory function in the H group rats. Multimodal MR imaging analysis revealed a decreased volume of the regional gray matter, lower CrCEST contrast and higher transport coefficient Ktrans in the hippocampus compared with the P group rats. Further correlation analysis found associations of quantitative MRI parameters of the hippocampus with the behavioral performance of H group rats. In this study, we validated the viability of using noninvasive multimodal MR imaging techniques to evaluate the effects of chronic exposure to a plateau hypoxic environment on the hippocampus.

Epigallocatechin-3-Gallate Ameliorated Iron Accumulation and Apoptosis and Promoted Neuronal Regeneration and Memory/Cognitive Functions in the Hippocampus Induced by Exposure to a Chronic High-Altitude Hypoxia Environment.

We aimed to explore the protective effects and potential treatment mechanism of Epigallocatechin-3-gallate (EGCG) in an animal model of chronic exposure in a natural high-altitude hypoxia (HAH) environment. Behavioral alterations were assessed with the Morris water maze test. Iron accumulation in the hippocampus was detected by using DAB enhanced Perls' staining, MRI, qPCR and colorimetry, respectively. Oxidative stress (malondialdehyde, MDA), apoptosis (Caspase-3), and neural regeneration (brain-derived neurotrophic factor, BDNF) were detected by using ELISA and western blotting. Neural ultrastructural changes were evaluated by transmission electron microscopy (TEM). The results showed that learning and memory performance of rats decreased when exposure to HAH environment. It was followed by iron accumulation, dysfunctional iron metabolism, reduced BDNF and the upregulation of MDA and Caspase-3. TEM confirmed the ultrastructural changes in neurons and mitochondria. EGCG reduced HAH-induced cognitive impairment, iron deposition, oxidative stress, and apoptosis and promoted neuronal regeneration against chronic HAH-mediated neural injury.

Machine learning to differentiate small round cell malignant tumors and non-small round cell malignant tumors of the nasal and paranasal sinuses using apparent diffusion coefficient values.

OBJECTIVE: We used radiomics feature-based machine learning classifiers of apparent diffusion coefficient (ADC) maps to differentiate small round cell malignant tumors (SRCMTs) and non-SRCMTs of the nasal and paranasal sinuses. MATERIALS: A total of 267 features were extracted from each region of interest (ROI). Datasets were randomized into two sets, a training set (∼70%) and a test set (∼30%). We performed dimensional reductions using the Pearson correlation coefficient and feature selection analyses (analysis of variance [ANOVA], relief, recursive feature elimination [RFE]) and classifications using 10 machine learning classifiers. Results were evaluated with a leave-one-out cross-validation analysis. RESULTS: We compared the AUC for all the pipelines in the validation dataset using FeAture Explorer (FAE) software. The pipeline using RFE feature selection and Gaussian process classifier yielded the highest AUCs with ten features. When the "one-standard error" rule was used, FAE produced a simpler model with eight features, including Perc.01%, Perc.10%, Perc.90%, Perc.99%, S(1,0) SumAverg, S(5,5) AngScMom, S(5,5) Correlat, and WavEnLH_s-2. The AUCs of the training, validation, and test datasets achieved 0.995, 0.902, and 0.710, respectively. For ANOVA, the pipeline with the auto-encoder classifier yielded the highest AUC using only one feature, Perc.10% (training/validation/test datasets: 0.886/0.895/0.809, respectively). For the relief, the AUCs of the training, validation, and test datasets that used the LRLasso classifier using five features (Perc.01%, Perc.10%, S(4,4) Correlat, S(5,0) SumAverg, S(5,0) Contrast) were 0.892, 0.886, and 0.787, respectively. Compared with the RFE and relief, the results of all algorithms of ANOVA feature selection were more stable with the AUC values higher than 0.800. CONCLUSIONS: We demonstrated the feasibility of combining artificial intelligence with the radiomics from ADC values in the differential diagnosis of SRCMTs and non-SRCMTs and the potential of this non-invasive approach for clinical applications. KEY POINTS: • The parameter with the best diagnostic performance in differentiating SRCMTs from non-SRCMTs was the Perc.10% ADC value. • Results of all the algorithms of ANOVA feature selection were more stable and the AUCs were higher than 0.800, as compared with RFE and relief. • The pipeline using RFE feature selection and Gaussian process classifier yielded the highest AUC.

Nicotinamide mononucleotide attenuates doxorubicin-induced cardiotoxicity by reducing oxidative stress, inflammation and apoptosis in rats.

Doxorubicin (DOX) is an effective and widely used antineoplastic drug. However, its clinical application is limited due to its dose-dependent cardiotoxicity. Great efforts have been made to explore the pathological mechanism of DOX-induced cardiotoxicity (DIC), but new drugs and strategies to alleviate cardiac damage are still needed. Here, we aimed to investigate the effect of nicotinamide mononucleotide (NMN) on DIC in rats. The results of the present study showed that DOX treatment significantly induced cardiac dysfunction and cardiac injury, whereas NMN alleviated these changes. In addition, NMN inhibited Dox-induced activation of nucleotide-binding domain-like receptor protein 3 (NLRP3) inflammasome-mediated inflammation, as evidenced by decreased caspase 1 and IL-1ß activity. Moreover, NMN treatment increased glutathione (GSH) levels and superoxide dismutase (SOD) activity and decreased the levels of malondialdehyde (MDA) and reactive oxygen species (ROS) in DOX-treated rats. Furthermore, NMN treatment mitigated DOX-induced cardiomyocyte apoptosis and cardiac fibrosis. In conclusion, the results indicated that NMN protects against DIC in rats by inhibiting NLRP3 inflammasome activation, oxidative stress, and apoptosis.

TDP-43 loss induces extensive cryptic polyadenylation in ALS/FTD.

Nuclear depletion and cytoplasmic aggregation of the RNA-binding protein TDP-43 is the hallmark of ALS, occurring in over 97% of cases. A key consequence of TDP-43 nuclear loss is the de-repression of cryptic exons. Whilst TDP-43 regulated cryptic splicing is increasingly well catalogued, cryptic alternative polyadenylation (APA) events, which define the 3' end of last exons, have been largely overlooked, especially when not associated with novel upstream splice junctions. We developed a novel bioinformatic approach to reliably identify distinct APA event types: alternative last exons (ALE), 3'UTR extensions (3'Ext) and intronic polyadenylation (IPA) events. We identified novel neuronal cryptic APA sites induced by TDP-43 loss of function by systematically applying our pipeline to a compendium of publicly available and in house datasets. We find that TDP-43 binding sites and target motifs are enriched at these cryptic events and that TDP-43 can have both repressive and enhancing action on APA. Importantly, all categories of cryptic APA can also be identified in ALS and FTD post mortem brain regions with TDP-43 proteinopathy underlining their potential disease relevance. RNA-seq and Ribo-seq analyses indicate that distinct cryptic APA categories have different downstream effects on transcript and translation. Intriguingly, cryptic 3'Exts occur in multiple transcription factors, such as ELK1, SIX3, and TLX1, and lead to an increase in wild-type protein levels and function. Finally, we show that an increase in RNA stability leading to a higher cytoplasmic localisation underlies these observations. In summary, we demonstrate that TDP-43 nuclear depletion induces a novel category of cryptic RNA processing events and we expand the palette of TDP-43 loss consequences by showing this can also lead to an increase in normal protein translation.

The role of sex and ovarian hormones in hippocampal damage and cognitive deficits induced by chronic exposure to hypobaric hypoxia.

Purpose: This study aims to investigate the role of sex and ovarian hormones in hippocampal damage and cognitive deficits and behavioral dysfunction in rats induced by chronic exposure to hypobaric hypoxia. Methods: Six-week-old male and female SD rats were housed for 3 months either in a real altitude (4,250 m) environment as the model of chronic hypobaric-hypoxia (CHH) or in a plain as controls. The animal behavioral and hippocampal neurons at subcellular, molecular, and ultrastructural levels were characterized after CHH exposure. Results: After 3 months of CHH exposure, (1) male CHH rats' serum testosterone level was lower than male controls' whereas female CHH rats' serum estradiol level was higher than female controls'; (2) Morris water maze test finds that male rats showed more learning and spatial memory deficits than female rats; (3) male rats showed more severe hippocampal damage, hippocampal inflammation, oxidative stress and decreased hippocampal integrity (neurogenesis and dendritic spine density) than female rats; (4) Western blot analysis shows that, compared with the male control group, in male CHH group's hippocampus, expression of nNOS, HO-1, and Bax protein increased whereas that of Bcl-2 protein decreased; (5) Expression of PON2 protein in male rats (CHH and controls) was lower than female rats (CHH and controls). In addition, CHH exposure decreased the expression of PON2 protein in both male and female rats; (6) qPCR analysis reveals that CHH exposure reduced the gene expression of N-methyl-D-aspartate receptor NR2A and NR2B subunits in male rats' hippocampus. In addition, compared with the sham CHH group, the expression level of PON2 protein decreased in the OVX-CHH group's hippocampus whereas oxidative stress, neuroinflammation, and degeneration of hippocampal neurons increased in the OVX-CHH group's hippocampus. Conclusion: After CHH exposure, male rats were significantly more likely than female rats to develop hippocampal damage, hippocampal neuroinflammation, and cognitive decline and deficits, suggesting that sex and ovarian hormones were significantly involved in regulating the rats' susceptibility to CHH exposure-induced hippocampal damage.

Left ventricular strain patterns and their relationships with cardiac biomarkers in hypertrophic cardiomyopathy patients with preserved left ventricular ejection fraction.

Aims: This study aims to assess left ventricular (LV) function in hypertrophic cardiomyopathy (HCM) patients with preserved left ventricular ejection fraction (LVEF) by LV strain patterns based on cardiac magnetic resonance feature tracking (CMR-FT) and to explore the relationships between LV strain patterns and cardiac biomarkers in these patients, such as cardiac troponin (cTnT) and N-terminal prohormone of the brain natriuretic peptide (NT-proBNP). Methods: A total of 64 HCM patients with preserved LVEF and 33 healthy people were included in this study. All subjects underwent contrast-enhanced CMR, and all patients took blood tests for cTnT and NT-proBNP during hospitalization. Results: Despite the absence of a significant difference in LVEF between HCM patients and healthy controls, almost all global and segmental strains in radial, circumferential, and longitudinal directions in the HCM group deteriorated significantly as compared to controls (p < 0.05). Moreover, some global and segmental strains correlated significantly with NT-proBNP and cTnT in HCM patients, and the best correlations were global radial strain (GRS) (r = -0.553, p < 0.001) and mid-ventricular radial strain (MRS) (r = -0.582, p < 0.001), respectively, with a moderate correlation. The receiver operating characteristic (ROC) results showed that among the LV deformation parameters, GRS [area under the curve (AUC), 0.76; sensitivity, 0.49; specificity, 1.00], MRS (AUC, 0.81; sensitivity, 0.77; specificity, 0.79) demonstrated greater diagnostic accuracy to predict elevated NT-proBNP, and abnormal cTnT, respectively. Their cut-off values were 21.17 and 20.94%, respectively. Finally, all global strains demonstrated moderate, good, and excellent intra- and inter-observer reproducibility. Conclusion: LV strain patterns can be used to assess the subclinical cardiac function of HCM patients on the merit of being more sensitive than LVEF. In addition, LV strain patterns can detect serious HCM patients and may be helpful to non-invasively predict elevated NT-proBNP and cTnT.

Protective effect of a chronic hypobaric hypoxic environment at high altitude on cardiotoxicity induced by doxorubicin in rats: a 7 T magnetic resonance study.

BACKGROUND: Doxorubicin (DOX)-induced cardiotoxicity (DIC), a major clinical problem, has no effective preventive therapies. We hypothesized that left ventricular (LV) systolic function would be improved in a chronic hypobaric hypoxia environment at high altitude. The purpose of this study was to investigate whether cardiovascular magnetic resonance could reveal the cardioprotective effect of chronic hypobaric hypoxia on DIC. METHODS: In total, 60 rats were randomly assigned to 1 of 6 groups (n=10 per group): the P group (plain), PD group (plain + DOX), HH group (high altitude), HHD4 group (high altitude + DOX for 4 weeks), HHD8 group (high altitude + DOX for 8 weeks), and HHD12 group (high altitude + DOX for 12 weeks). The rats were transported to either Yushu (altitude: 4,250 m) or Chengdu (altitude: 500 m) where they underwent intraperitoneal injection of DOX (5 mg/kg/week for 3 weeks) or saline. Preclinical 7 T cardiovascular magnetic resonance was performed at weeks 4, 8, and 12. Tissue tracking was used to measure LV cardiac function and to analyze global and segmental strains. Subsequently, histological and oxidative stress tests were performed to evaluate the protective effect of a high-altitude environment on DIC. RESULTS: The left ventricular ejection fraction (LVEF) and global and regional strains in the middle, apical, anterior, septal, inferior, and lateral segments (all P<0.05) were improved in the HHD4 group compared with the PD group. The global strain was significantly greater in absolute value in the HHD8 and HHD12 groups than in the HHD4 group (all P<0.05). Additionally, histological and enzyme-linked immunosorbent assay evaluations supported the in vivo results. CONCLUSIONS: A chronic hypobaric and hypoxic environment at high altitude partially prevented cardiac dysfunction and increased global and regional strain in DIC rat models, thereby minimizing myocardial injury and fibrosis. In addition, by increasing the total duration of chronic hypobaric hypoxia, the global strain was further increased, which was likely due to reduced oxidative stress.