Strong Protection by 4-Hydroxyestrone against Erastin-Induced Ferroptotic Cell Death in Estrogen Receptor-Negative Human Breast Cancer Cells: Evidence for Protein Disulfide Isomerase as a Mechanistic Target for Protection.

Ferroptosis is a recently identified form of regulated cell death, characterized by excessive iron-dependent lipid peroxidation. Recent studies have demonstrated that protein disulfide isomerase (PDI) is an important mediator of chemically induced ferroptosis and also a new target for protection against ferroptosis-associated cell death. In the present study, we identified that 4-hydroxyestrone (4-OH-E1), a metabolic derivative of endogenous estrogen, is a potent small-molecule inhibitor of PDI, and can strongly protect against chemically induced ferroptotic cell death in the estrogen receptor-negative MDA-MB-231 human breast cancer cells. Pull-down and CETSA assays demonstrated that 4-OH-E1 can directly bind to PDI both in vitro and in intact cells. Computational modeling analysis revealed that 4-OH-E1 forms two hydrogen bonds with PDI His256, which is essential for its binding interaction and thus inhibition of PDI's catalytic activity. Additionally, PDI knockdown attenuates the protective effect of 4-OH-E1 as well as cystamine (a known PDI inhibitor) against chemically induced ferroptosis in human breast cancer cells. Importantly, inhibition of PDI by 4-OH-E1 and cystamine or PDI knockdown by siRNAs each markedly reduces iNOS activity and NO accumulation, which has recently been demonstrated to play an important role in erastin-induced ferroptosis. In conclusion, this study demonstrates that 4-OH-E1 is a novel inhibitor of PDI and can strongly inhibit ferroptosis in human breast cancer cells in an estrogen receptor-independent manner. The mechanistic understanding gained from the present study may also aid in understanding the estrogen receptor-independent cytoprotective actions of endogenous estrogen metabolites in many noncancer cell types.

Attenuation of amyloid-ß-induced mitochondrial dysfunction by active components of anthocyanins in HT22 neuronal cells.

Alzheimer's disease (AD) is a common form of neurodegenerative disease in the elderly. Amyloid-ß (Aß)-associated neurotoxicity is an important component of the neurodegenerative change in AD. Recent studies have revealed a beneficial effect of anthocyanins in improving learning and memory in AD animal models. Using cultured HT22 mouse hippocampal neuronal cells as an in vitro model, we examined in this study the protective effect of ten pure components of anthocyanins against Aß 42-induced cytotoxicity and also investigated the mechanism of their protective effects. We found that treatment of HT22 cells with the pure components of anthocyanins dose-dependently rescued Aß 42-induced cytotoxicity, with slightly different potencies. Using petunidin as a representative compound, we found that it enhanced mitochondrial homeostasis and function in Aß 42-treated HT22 cells. Mechanistically, petunidin facilitated ß-catenin nuclear translocation and enhanced the interaction between ß-catenin and TCF7, which subsequently upregulated mitochondrial homeostasis-related protein Mfn2, thereby promoting restoration of mitochondrial homeostasis and function in Aß 42-treated HT22 cells. Together, these results reveal that the pure components of anthocyanins have a strong protective effect in HT22 cells against Aß 42-induced cytotoxicity by ameliorating mitochondrial homeostasis and function in a ß-catenin/TCF-dependent manner.

Biochemical mechanism of erastin-induced ferroptotic cell death in neuronal cells.

Ferroptosis is a new form of nonapoptotic cell death closely associated with glutathione (GSH) peroxidase 4 inhibition and/or GSH depletion, resulting in the accumulation of cellular iron and lipid peroxides. The exact mechanism by which GSH depletion causes the accumulation of reactive oxygen species (ROS) and lipid-ROS and subsequent ferroptotic cell death in neuronal cells remains unclear. In the present study, using immortalized HT22 mouse hippocampal neuronal cells as a model, we show that nitric oxide (NO) accumulation via protein disulfide isomerase (PDI)-mediated neuronal nitric oxide synthase (nNOS) activation plays a critical role in chemically-induced ferroptosis. Mechanistically, we find that erastin-induced GSH depletion leads to activation of PDI, which then mediates ferroptosis by catalyzing nNOS dimerization, followed by accumulation of cellular NO, ROS and lipid ROS and ultimately ferroptotic cell death. Pharmacological inhibition of PDI enzymatic activity or selective PDI knockdown can effectively abrogate erastin-induced ferroptosis in HT22 cells. The results of this study reveal an important role of PDI in mediating chemically induced ferroptosis in a neuronal cell model, and PDI may serve as a potential drug target for protection against GSH depletion-associated ferroptotic neuronal cell death.

Protection against glutathione depletion-associated oxidative neuronal death by neurotransmitters norepinephrine and dopamine: Protein disulfide isomerase as a mechanistic target for neuroprotection.

Oxidative stress is extensively involved in neurodegeneration. Clinical evidence shows that keeping the mind active through mentally-stimulating physical activities can effectively slow down the progression of neurodegeneration. With increased physical activities, more neurotransmitters would be released in the brain. In the present study, we investigated whether some of the released neurotransmitters might have a beneficial effect against oxidative neurodegeneration in vitro. Glutamate-induced, glutathione depletion-associated oxidative cytotoxicity in HT22 mouse hippocampal neuronal cells was used as an experimental model. We showed that norepinephrine (NE, 50 µM) or dopamine (DA, 50 µM) exerted potent protective effect against glutamate-induced cytotoxicity, but this effect was not observed when other neurotransmitters such as histamine, γ-aminobutyric acid, serotonin, glycine and acetylcholine were tested. In glutamate-treated HT22 cells, both NE and DA significantly suppressed glutathione depletion-associated mitochondrial dysfunction including mitochondrial superoxide accumulation, ATP depletion and mitochondrial AIF release. Moreover, both NE and DA inhibited glutathione depletion-associated MAPKs activation, p53 phosphorylation and GADD45α activation. Molecular docking analysis revealed that NE and DA could bind to protein disulfide isomerase (PDI). In biochemical enzymatic assay in vitro, NE and DA dose-dependently inhibited the reductive activity of PDI. We further revealed that the protective effect of NE and DA against glutamate-induced oxidative cytotoxicity was mediated through inhibition of PDI-catalyzed dimerization of the neuronal nitric oxide synthase. Collectively, the results of this study suggest that NE and DA may have a protective effect against oxidative neurodegeneration through inhibition of protein disulfide isomerase and the subsequent activation of the MAPKs‒p53‒GADD45α oxidative cascade.

Effect of Silage Diet (Sweet Sorghum vs. Whole-Crop Corn) and Breed on Growth Performance, Carcass Traits, and Meat Quality of Lambs.

Diet and breed directly affect ruminant carcass traits and meat quality. Therefore, this research aimed to evaluate the effect of silage diet and breed on growth performance, carcass traits, and meat quality of lambs. A total of 28, 3-4 months old female lambs consisting of 14 Dorper lambs (DP) and 14 Thin-tailed Han lambs (TH) were allocated in a 2 × 2 factorial design and offered two experimental diets (sweet sorghum silage: SS; whole-crop corn silage: WS) for 90 days. Lambs fed the WS diet had a higher growth performance (p < 0.01), intramuscular fat content (p < 0.05), and bright meat color (p < 0.01) than lambs fed the SS diet. The lambs fed the SS diet showed a higher polyunsaturated fatty acid (PUFA) content than the lambs fed the WS diet (p < 0.01); there was no significant difference in growth performance and carcass characteristics between DP and TH lambs (p > 0.05). The meat of the DP lambs showed lower values of initial pH, shear force, lightness (L*), redness (a*), and saturated fatty acid (SFA) content (p < 0.05). The lamb breed influenced fewer variables of growth performance and carcass characteristics compared to the diet. The lambs fed the SS diet had higher nutritional quality meat than lambs fed the WS diet.

A Study on Weak Edge Detection of COVID-19's CT Images Based on Histogram Equalization and Improved Canny Algorithm.

The coronavirus disease 2019 (COVID-19) is a substantial threat to people's lives and health due to its high infectivity and rapid spread. Computed tomography (CT) scan is one of the important auxiliary methods for the clinical diagnosis of COVID-19. However, CT image lesion edge is normally affected by pixels with uneven grayscale and isolated noise, which makes weak edge detection of the COVID-19 lesion more complicated. In order to solve this problem, an edge detection method is proposed, which combines the histogram equalization and the improved Canny algorithm. Specifically, the histogram equalization is applied to enhance image contrast. In the improved Canny algorithm, the median filter, instead of the Gaussian filter, is used to remove the isolated noise points. The K-means algorithm is applied to separate the image background and edge. And the Canny algorithm is improved continuously by combining the mathematical morphology and the maximum between class variance method (OTSU). On selecting four types of lesion images from COVID-CT date set, MSE, MAE, SNR, and the running time are applied to evaluate the performance of the proposed method. The average values of these evaluation indicators are 1.7322, 7.9010, 57.1241, and 5.4887, respectively. Compared with other three methods, these values indicate that the proposed method achieves better result. The experimental results prove that the proposed algorithm can effectively detect the weak edge of the lesion, which is helpful for the diagnosis of COVID-19.

Clinical characteristics of 71 patients with coronavirus disease 2019. / 71例2019å† çŠ¶ç— æ¯’ç— ä¸´åºŠç‰¹å¾åˆ†æž.

OBJECTIVES: To analyze the clinical characteristics of 71 patients with coronavirus disease 2019 (COVID-19). METHODS: The general data, epidemiological data, laboratory tests, imaging examinations, and treatment of 71 patients with COVID-19 admitted to the Sixth People's Hospital of Zhengzhou from January 19, 2020 to March 3, 2020 were retrospectively analyzed. RESULTS: Of the 71 COVID-19 patients, the ages were 4-84 (41.29±15.21) years, 38 (53.5%) patients were male, 33 (46.5%) were female, and 52 (73.2%) were in 22 clusters. The main clinical manifestations were fever (78.9%), cough (64.8%), and sputum (38.0%). The fever was mainly low and moderate, with 49 patients (69.0%) at 37.3-39.0 ℃. Most of the leukocytes, neutrophils, and lymphocytes were normal, accounting for 47 (66.2%), 51 (71.8%), and 51 (71.8%) patients, respectively; a few of them were decreased, accounting for 21 (29.6%), 16 (22.5%), and 20 (28.2%) patients, respectively. There were 38 (53.5%) and 31 (43.7%) patients with the decreased CD4+ and CD8+ T cell counts, respectively. There were 41 (57.7%), 38 (53.5%), 32 (45.1%), 26(36.6%), 22 (31.0%), 20 (28.2%), 14 (19.7%), 14 (19.7%), and 9 (12.7%) patients with the increased levels of C-reactive protein, erythrocyte sedimentation rate, procalcitonin, fibrinogen,interleukin 6, lactate dehydrogenase,D-dimer,alanine aminotransferase, and aspartate aminotransferase, respectively. Of the 71 patients, the lung was involved in 60 (84.5%) patients, the double lung was involved in 47 (66.2%) patients, and the single lung was involved in 13 (18.3%) patients. The course of the disease was long, and the time from symptom onset to the second severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleic acid negative transformation was (17.22±6.34) days.There were no significant differences in the incubation period (t=-0.453, P>0.05), the complicates (χ2=0.042, P>0.05), and the time from symptom onset to diagnosis (t=-1.330, P>0.05) in patients between the non-severe group and the severe group. The onset age, gender, SARS-CoV-2 nucleic acid negative time, lymphocyte count, D-dimer, C-reactive protein, total bilirubin, direct bilirubin, lactate dehydrogenase, calcium ion, CD4+ T cell count, CD8+ T cell count, calcitonin, procalcitonin, and troponin were significantly different between the severe group and the non-severe group (all P<0.05). Among the 71 patients, 4 (5.6%) patients were mild, 59 (83.1%) were normal, and 8 (11.3%) were severe or critical. CONCLUSIONS: The aggregation phenomenon of COVID-19 is obvious. Fever and cough are the main clinical manifestations. White blood cells, neutrophils, and lymphocytes in the most patients in the early onset are normal. Most COVID-19 patients are light and ordinary type, with good prognosis.