Gut microbiota-dependent phenylacetylglutamine in cardiovascular disease: current knowledge and new insights

Phenylacetylglutamine (PAGln) is an amino acid derivate that comes from the amino acid phenylalanine. There are increasing studies showing that the level of PAGln is associated with the risk of different cardiovascular diseases. In this review, we discussed the metabolic pathway of PAGln production and the quantitative measurement methods of PAGln. We summarized the epidemiological evidence to show the role of PAGln in diagnostic and prognostic value in several cardiovascular diseases, such as heart failure, coronary heart disease/atherosclerosis, and cardiac arrhythmia. The underlying mechanism of PAGln is now considered to be related to the thrombotic potential of platelets via adrenergic receptors. Besides, other possible mechanisms such as inflammatory response and oxidative stress could also be induced by PAGln. Moreover, since PAGln is produced across different organs including the intestine, liver, and kidney, the cross-talk among multiple organs focused on the function of this uremic toxic metabolite. Finally, the prognostic value of PAGln compared to the classical biomarker was discussed and we also highlighted important gaps in knowledge and areas requiring future investigation of PAGln in cardiovascular diseases.

Self-recruited neutrophils trigger over-activated innate immune response and phenotypic change of cardiomyocytes in fulminant viral myocarditis

Fulminant myocarditis (FM) is a life-threatening inflammatory disease. However, the mechanisms underlying its acute onset are unknown. By dynamic cardiac function measurement, we discovered that the initiation of sudden hemodynamic collapse was on day 4 in the mouse model of FM. Single-cell RNA-sequencing study revealed that healthy cardiomyocytes (CMs) lost their contractile and metabolic function and differentiated into pro-angiogenic and pro-inflammatory CMs. Meanwhile, neutrophils, the most expanded immune cells, exhibited a unique developmental trajectory only after migrating to the heart, where they continuously attracted peripheral neutrophils via Cxcl2/Cxcl3, resulting in the acute accumulation of neutrophils in the heart. Well-differentiated cardiac-infiltrating neutrophils, rather than viruses, induced phenotypic changes in CMs. Moreover, neutrophils could amplify cytokine storm by recruiting and activating pro-inflammatory monocytes. Blockade of the self-recruiting loop of neutrophils by targeting the Cxcl2/Cxcl3-Cxcr2 axis substantially alleviated FM in mice. Collectively, we provide a comprehensive single-cell atlas of immune cells and CMs in FM, elucidate the disease pathogenesis, and suggest potential therapeutic strategies.

[Incidence and prognosis of olfactory and gustatory dysfunctions related to infection of SARS-CoV-2 Omicron strain: a national multi-center survey of 35 566 population]

Objective: This cross-sectional investigation aimed to determine the incidence, clinical characteristics, prognosis, and related risk factors of olfactory and gustatory dysfunctions related to infection with the SARS-CoV-2 Omicron strain in mainland China. Methods: Data of patients with SARS-CoV-2 from December 28, 2022, to February 21, 2023, were collected through online and offline questionnaires from 45 tertiary hospitals and one center for disease control and prevention in mainland China. The questionnaire included demographic information, previous health history, smoking and alcohol drinking, SARS-CoV-2 vaccination, olfactory and gustatory function before and after infection, other symptoms after infection, as well as the duration and improvement of olfactory and gustatory dysfunction. The self-reported olfactory and gustatory functions of patients were evaluated using the Olfactory VAS scale and Gustatory VAS scale. Results: A total of 35 566 valid questionnaires were obtained, revealing a high incidence of olfactory and taste dysfunctions related to infection with the SARS-CoV-2 Omicron strain (67.75%). Females(χ2=367.013, P<0.001) and young people(χ2=120.210, P<0.001) were more likely to develop these dysfunctions. Gender(OR=1.564, 95%CI: 1.487-1.645), SARS-CoV-2 vaccination status (OR=1.334, 95%CI: 1.164-1.530), oral health status (OR=0.881, 95%CI: 0.839-0.926), smoking history (OR=1.152, 95%CI=1.080-1.229), and drinking history (OR=0.854, 95%CI: 0.785-0.928) were correlated with the occurrence of olfactory and taste dysfunctions related to SARS-CoV-2(above P<0.001). 44.62% (4 391/9 840) of the patients who had not recovered their sense of smell and taste also suffered from nasal congestion, runny nose, and 32.62% (3 210/9 840) suffered from dry mouth and sore throat. The improvement of olfactory and taste functions was correlated with the persistence of accompanying symptoms(χ2=10.873, P=0.001). The average score of olfactory and taste VAS scale was 8.41 and 8.51 respectively before SARS-CoV-2 infection, but decreased to3.69 and 4.29 respectively after SARS-CoV-2 infection, and recovered to 5.83and 6.55 respectively at the time of the survey. The median duration of olfactory and gustatory dysfunctions was 15 days and 12 days, respectively, with 0.5% (121/24 096) of patients experiencing these dysfunctions for more than 28 days. The overall self-reported improvement rate of smell and taste dysfunctions was 59.16% (14 256/24 096). Gender(OR=0.893, 95%CI: 0.839-0.951), SARS-CoV-2 vaccination status (OR=1.334, 95%CI: 1.164-1.530), history of head and facial trauma(OR=1.180, 95%CI: 1.036-1.344, P=0.013), nose (OR=1.104, 95%CI: 1.042-1.171, P=0.001) and oral (OR=1.162, 95%CI: 1.096-1.233) health status, smoking history(OR=0.765, 95%CI: 0.709-0.825), and the persistence of accompanying symptoms (OR=0.359, 95%CI: 0.332-0.388) were correlated with the recovery of olfactory and taste dysfunctions related to SARS-CoV-2 (above P<0.001 except for the indicated values). Conclusion: The incidence of olfactory and taste dysfunctions related to infection with the SARS-CoV-2 Omicron strain is high in mainland China, with females and young people more likely to develop these dysfunctions. Active and effective intervention measures may be required for cases that persist for a long time. The recovery of olfactory and taste functions is influenced by several factors, including gender, SARS-CoV-2 vaccination status, history of head and facial trauma, nasal and oral health status, smoking history, and persistence of accompanying symptoms.

DISC1 inhibits GSK3β activity to prevent tau hyperphosphorylation under diabetic encephalopathy

Diabetic encephalopathy (DE) is a common complication of type 2 diabetes (T2D), especially in those patients with long T2D history. Persistent high glucose (HG) stimulation leads to neuron damage and manifests like Alzheimer's disease's pathological features such as neurofilament tangle. However, the precise mechanism of high-glucose-induced tau hyperphosphorylation is not fully revealed. We here gave evidence that Disrupted in schizophrenia 1 protein (DISC1) could interact with glycogen synthase kinase 3β (GSK3β) and inhibit its activity to prevent tau hyperphosphorylation. By using DB/DB mice as animal model and HG-treated N2a cell as cell model, we found that DISC1 was downregulated both in vivo and in vitro, complicated with Tau hyperphosphorylation and GSK3β activation. Further, we identified DISC1 interacted with GSK3β by its 198th-237th amino acid residues. Overexpression of full length DISC1 but not mutated DISC1 lacking this domain could prevent HG induced tau hyperphosphorylation. Taken together, our work revealed DISC1 could be an important negative modulators of tau phosphorylation, and suggested that preservation of DISC1 could prevent HG induced neuron damage.

Salvianolic Acid Ameliorates Pressure Overload-Induced Cardiac Endothelial Dysfunction via Activating HIF1[Formula: see text]/HSF1/CD31 Pathway

Pressure overload is a major risk factor for various cardiovascular diseases. Disorders of the endothelium are involved in the pathological mechanisms of pressure, and maintaining endothelial function is a practical strategy to alleviate pressure overload-induced cardiac injury. In this study, we provided evidence that salvianolic acid, the active component of Danshen, a traditional Chinese herb medicine, preserved pressure overload-induced cardiac dysfunction via protecting endothelium. Male C57BL/6J mice were imposed with transverse aortic constriction to mimic pressure overload and treated with salvianolic acid (200[Formula: see text]mg/kg/day) or vehicle for 6 weeks. The hemodynamic and cardiac functional parameters were detected by the cardiac catheter and transthoracic echocardiography. The pathological measurements were conducted by heart hematoxylin-eosin, wheat germ agglutinin staining, Masson's trichrome staining, and immunofluorescence staining. Endothelial cell (EC) proliferation was estimated using the Cell Counting Kit-8, EC migration was evaluated by scratched assay, and EC integrity was observed by electron microscope. Salvianolic acid notably inhibited cardiac chamber enlargement, restrained cardiac contractile dysfunction, and repressed cardiac fibrosis caused by chronic pressure overload. Salvianolic acid maintained endothelial tight junction integrity by boosting the expression of CD31. Furthermore, the endothelial protective effect of salvianolic acid against pressure overload is dependent on the activation of hypoxia-inducible factor 1[Formula: see text], which consequently activated heat shock factor 1 and promoted CD31 expression. Our study uncovered that salvianolic acid protected cardiac ECs against pressure overload via a HIF1[Formula: see text]/HSF1/CD31 pathway, indicating a potential appliance of salvianolic acid in hypertensive heart disease.

Pirfenidone alleviates cardiac fibrosis induced by pressure overload via inhibiting TGF-β1/Smad3 signalling pathway

Cardiac fibrosis critically injured the cardiac structure and function of the hypertensive patients. However, the anti‐fibrotic strategy is still far from satisfaction. This study aims to determine the effect and mechanism of Pirfenidone (PFD), an anti‐lung fibrosis medicine, in the treatment of cardiac fibrosis and heart failure induced by pressure overload. Male C57BL/6 mice were subjected to thoracic aorta constriction (TAC) or sham surgery with the vehicle, PFD (300 mg/kg/day) or Captopril (CAP, 20 mg/kg/day). After 8 weeks of surgery, mice were tested by echocardiography, and then sacrificed followed by morphological and molecular biological analysis. Compared to the sham mice, TAC mice showed a remarkable cardiac hypertrophy, interstitial and perivascular fibrosis and resultant heart failure, which were reversed by PFD and CAP significantly. The enhanced cardiac expression of TGF‐β1 and phosphorylation of Smad3 in TAC mice were both restrained by PFD. Cardiac fibroblasts isolated from adult C57BL/6 mice were treated by Angiotensin II, which led to significant increases in cellular proliferation and levels of α‐SMA, vimentin, TGF‐β1 and phosphorylated TGF‐β receptor and Smad3. These changes were markedly inhibited by pre‐treatment of PFD. Collectively, PFD attenuates myocardial fibrosis and dysfunction induced by pressure overload via inhibiting the activation of TGF‐β1/Smad3 signalling pathway.

RBM20, a Therapeutic Target to Alleviate Myocardial Stiffness via Titin Isoforms Switching in HFpEF

Increased myocardial stiffness is critically involved in heart diseases with impaired cardiac compliance, especially heart failure with preserved ejection fraction (HFpEF). Myocardial stiffness mainly derives from cardiomyocyte- and extracellular matrix (ECM)-derived passive stiffness. Titin, a major component of sarcomeres, participates in myocardial passive stiffness and stress-sensitive signaling. The ratio of two titin isoforms, N2BA to N2B, was validated to influence diastolic dysfunction via several pathways. RNA binding motif protein 20 (RBM20) is a well-studied splicing factor of titin, functional deficiency of RBM20 in mice profile improved cardiac compliance and function, which indicated that RBM20 functions as a potential therapeutic target for mitigating myocardial stiffness by modulating titin isoforms. This minor review summarized how RBM20 and other splicing factors modify the titin isoforms ratio, therefore providing a promising target for improving the myocardial compliance of HFpEF.

GSK-J4, a Specific Histone Lysine Demethylase 6A Inhibitor, Ameliorates Lipotoxicity to Cardiomyocytes via Preserving H3K27 Methylation and Reducing Ferroptosis

Changes in modern lifestyle provoke a series of metabolic stresses such as hyperlipidemia. Excessive free fatty acids induce cardiomyocyte metabolic reprogramming and rearrangement of the lipid content of cardiomyocyte and promote oxidative stress. As a newly defined lipid peroxidation-related cell death pathway, the role of ferroptosis in metabolic stress-induced cardiomyocyte injury is poorly revealed. Our work indicates that GSK-J4, a histone lysine demethylase 6A/6B dual inhibitor, can alleviate palmitic acid (PA)-induced hypersensitivity to ferroptosis by suppressing H3K27 demethylation. Mechanistically, PA stimulation reduces the H3K27me3 level and hence promotes the expression of ACSL4, a key lipid modulator of ferroptosis. GSK-J4 pretreatment significantly preserves the H3K27me3 level and reduces the ACSL4 level. GSK-J4 also reduces reactive oxygen species to alleviate oxidative stress, which further decreases lipid peroxidation. Taken together, our data suggest that cardiomyocyte undergoes epigenetic reprogramming under metabolic challenges, rearranging lipid content, and sensitizing to ferroptosis. GSK-J4 can be a potential drug for treating hyperlipidemia-induced cardiomyocyte injury by targeting epigenetic modulations.

Emerging Roles of Ceramide in Cardiovascular Diseases

Ceramide is a core molecule of sphingolipid metabolism that causes selective insulin resistance and dyslipidemia. Research on its involvement in cardiovascular diseases has grown rapidly. In resting cells, ceramide levels are extremely low, while they rapidly accumulate upon encountering external stimuli. Recently, the regulation of ceramide levels under pathological conditions, including myocardial infarction, hypertension, and atherosclerosis, has drawn great attention. Increased ceramide levels are strongly associated with adverse cardiovascular risks and events while inhibiting the synthesis of ceramide or accelerating its degradation improves a variety of cardiovascular diseases. In this article, we summarize the role of ceramide in cardiovascular disease, investigate the possible application of ceramide as a new diagnostic biomarker and a therapeutic target for cardiovascular disorders, and highlight the remaining problems.

Trimetazidine Attenuates Heart Failure by Improving Myocardial Metabolism via AMPK

Energic deficiency of cardiomyocytes is a dominant cause of heart failure. An antianginal agent, trimetazidine improves the myocardial energetic supply. We presumed that trimetazidine protects the cardiomyocytes from the pressure overload-induced heart failure through improving the myocardial metabolism. C57BL/6 mice were subjected to transverse aortic constriction (TAC). After 4 weeks of TAC, heart failure was observed in mice manifested by an increased left ventricular (LV) chamber dimension, an impaired LV ejection fraction evaluated by echocardiography analysis, which were significantly restrained by the treatment of trimetazidine. Trimetazidine restored the mitochondrial morphology and function tested by cardiac transmission electron microscope and mitochondrial dynamic proteins analysis. Positron emission tomography showed that trimetazidine significantly elevated the glucose uptake in TAC mouse heart. Trimetazidine restrained the impairments of the insulin signaling in TAC mice and promoted the translocation of glucose transporter type IV (GLUT4) from the storage vesicle to membrane. However, these cardioprotective effects of trimetazidine in TAC mice were notably abolished by compound C (C.C), a specific AMPK inhibitor. The enlargement of neonatal rat cardiomyocyte induced by mechanical stretch, together with the increased expression of hypertrophy-associated proteins, mitochondria deformation and dysfunction were significantly ameliorated by trimetazidine. Trimetazidine enhanced the isolated cardiomyocyte glucose uptake in vitro. These benefits brought by trimetazidine were also removed with the presence of C.C. In conclusion, trimetazidine attenuated pressure overload-induced heart failure through improving myocardial mitochondrial function and glucose uptake via AMPK.

N-Acetyl Cysteine Ameliorates High-Fat Diet-Induced Nonalcoholic Fatty Liver Disease and Intracellular Triglyceride Accumulation by Preserving Mitochondrial Function

Rationale: Nonalcoholic fatty liver disease (NAFLD) is a kind of metabolic disease characterized by liver steatosis. Excessive reactive oxygen species (ROS) originating from dysfunctional mitochondria is the major pathophysiological contributor in the development of NAFLD and is thought to be a promising therapeutic target. A few reports demonstrate the antioxidative treatments for NAFLD.

Methods: Male C57 mice were fed on a normal chow diet (ND) or high-fat diet (HFD) for 8 weeks. PBS or N-acetyl cysteine (NAC) was gavaged to mice. LO2 human liver cell line treated with palmitic acid (PA) was applied as a cellular model. Western blot, immunofluorescence, biochemistry assay, and pathological staining were used to investigate the mechanism of suppressing lipid accumulation of NAC.

Results: NAC treatment was able to prevent HFD-induced NAFLD, as evidenced by less hepatic triglyceride accumulation and lipid droplet formation compared with that of mice in the HFD group. NAC could preserve mitochondrial function by inhibiting excessive mitophagy and promoting mitochondria biogenesis to prevent ROS production. NAC also activated Sirt1 and preserved its protein level and subsequently promoted mitochondria biogenesis via deacetylating PGC1a.

Conclusion: We demonstrated that NAC may be an effective drug to treat NAFLD, which was related to its antioxidative and mitochondrial protective effect.

MicroRNA-203a-3p affects the biological characteristics of nasopharyngeal carcinoma by targeting vascular endothelial growth factor-C

Nasopharyngeal carcinoma (NPC) has a high incidence in Southeast Asia and China. This study aims to investigate the effect of miR-203a-3p and vascular endothelial growth factor-C (VEGF-C) on nasopharyngeal carcinoma. In this study, we investigate the transfection of miR-203a-3p mimics and the ability of miR-203a-3p to inhibit in nasopharyngeal carcinoma cell line 5-8F and C666-1, the expression levels of protein AKT, p-AKT in VEGF-C and the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) signal pathway by plate clone formation experiment, flow cytometer PI staining method, transwell cell experiment, vasculogenic mimicry experiment, and Western blot. The results showed that miR-203a-3p in the nasopharyngeal carcinoma cell line significantly decreased, while VEGF-C in nasopharyngeal carcinoma tissues and cell lines significantly increased. Furthermore, miR-203a-3p inhibited the proliferation of nasopharyngeal carcinoma cells and blocked the cell cycle of nasopharyngeal carcinoma in the G⁰/G¹ phase, reduced the vasculogenic phenomena and epithelial-mesenchymal transition of nasopharyngeal carcinoma cells, and effectively inhibited the growth of nasopharyngeal carcinoma in vivo. The low expression of VEGF-C can inhibit the proliferation, vasculogenic mimicry, and epithelial-mesenchymal transition of nasopharyngeal carcinoma cells. We found that miR-203a-3p was expressed to a low degree in nasopharyngeal carcinoma. Furthermore, miR-203a-3p regulated the PI3K/AKT signal pathway by downregulating the expression of VEGF-C, thereby inhibiting the proliferation, migration, invasion, vasculogenic mimicry, epithelial-mesenchymal transition, and other malignant biological characteristics of nasopharyngeal carcinoma cells.

Endothelial dysfunction in COVID-19 calls for immediate attention: the emerging roles of the endothelium in inflammation caused by SARS-CoV-2

The COVID-19 pandemic has caused numerous deaths around the world. A growing body of evidence points to the important role of overwhelming inflammatory responses in the pathogenesis of COVID-19 and the effectiveness of anti-inflammation therapy against COVID-19 is emerging. In addition to affecting the lungs, COVID-19 can be a severe systemic inflammatory disease that is related to endothelial dysfunction. We are calling for closer attention to endothelial dysfunction in COVID-19 not only for fully revealing the pathogenic mechanism of COVID-19 but also for properly adjusting the strategy of clinical intervention.

ApoE4 (Δ272-299) induces mitochondrial-associated membrane formation and mitochondrial impairment by enhancing GRP75-modulated mitochondrial calcium overload in neuron

Background

Apolipoprotein E4 (apoE4) is a major genetic risk factor of Alzheimer’s disease. Its C-terminal-truncated apoE4 (Δ272–299) has neurotoxicity by affecting mitochondrial respiratory function. However, the molecular mechanism(s) underlying the action of apoE4 (Δ272–299) in mitochondrial function remain poorly understood.

Methods

The impact of neuronal apoE4 (Δ272–299) expression on ER stress, mitochondrial-associated membrane (MAM) formation, GRP75, calcium transport and mitochondrial impairment was determined in vivo and in vitro. Furthermore, the importance of ER stress or GRP75 activity in the apoE4 (Δ272–299)-promoted mitochondrial dysfunction in neuron was investigated.

Results

Neuronal apoE4 (Δ272–299) expression induced mitochondrial impairment by inducing ER stress and mitochondrial-associated membrane (MAM) formation in vivo and in vitro. Furthermore, apoE4 (Δ272–299) expression promoted GRP75 expression, mitochondrial dysfunction and calcium transport into the mitochondria in neuron, which were significantly mitigated by treatment with PBA (an inhibitor of ER stress), MKT077 (a specific GRP75 inhibitor) or GRP75 silencing.

Conclusions

ApoE4 (Δ272–299) significantly impaired neuron mitochondrial function by triggering ER stress, up-regulating GRP75 expression to increase MAM formation, and mitochondrial calcium overload. Our findings may provide new insights into the neurotoxicity of apoE4 (Δ272–299) against mitochondrial function and uncover new therapeutic targets for the intervention of Alzheimer’s disease.

[Analysis on endoscopic endonasal approach combined with the frontotemporal orbitozygomatic approach under the microscope for skull base tumor with intra and extra-cranial involvement]

Objective: To evaluate the application of combination use of endoscopic endonasal approach combined with the frontotemporal orbitozygomatic approach microscopically in skull base tumor with intra and extra-cranial involvement. Methods: A total of 7 patients (4 males and 3 females, aging from 27 to 65 years old, with a medium age of 48) undergone complicated skull base surgeries via endoscopic endonasal approach combined with the frontotemporal orbitozygomatic approach microscopically from May 2016 to January 2018 were reviewed respectively. The patients included 2 cases of recurrent invasive pituitary adenoma, 3 cases of basal skull meningiomas, 1 case of clivus chondrosarcoma, and 1 case of recurrent nasopharyngeal carcinoma. The lesion extensively infiltrated nasal cavity, extending to the paranasal sinus, bilateral cavernous sinus, sellar region, suprasellar, superior clivus, temporal lobe, pterygopalatine fossa, infratemporal fossa and important intracranial vessels. All the 7 patients were treated under general anesthesia by endoscopic endonasal approach combined with frontotemporal orbitozygomatic approach under the microscope. Total excision rate, intraoperative and postoperative complications and postoperative curative effect were observed. All of them were followed up for 6 to 12 months. The Glasgow Outcome Scale (GOS) was used to evaluate the prognosis. Result: Total tumor removal was performed in 5 cases, subtotal removel in 2 cases. There was no complication during the operation. Postoperative severe complications occurred in 2 cases, including 1 case of cerebrospinal fluid rhinorrhea and intracranial infection, which was cured by lumbar cistern drainage and intrathecal injection; 1 case occurred oculomotor nerve paralysis, which recovered during follow-up. Postoperative complications occurred in 1 case of trochlear nerve dysfunction, 2 cases of facial numbness, and 1 case of tinnitus. During follow-up, all patients recovered to varying degrees. There was no bleeding and death after the operation. No tumor recurred during the follow-up period. All patients were recovered well with GOS grade Ⅳ-Ⅴ. Conclusions: Endoscopic transnasal approach combined with microscopic frontotemporal orbitozygomatic approach can remove tumors in one stage, reduce surgical complications and improve surgical effect. It has good application prospects and is suitable for excising complex intracranial and extracranial communicating tumors of widely involving sellar, clivus and petrous apex area.

Trimetazidine in Heart Failure

Heart failure is a systemic syndrome caused by multiple pathological factors. Current treatments do not have satisfactory outcomes. Several basic studies have revealed the protective effect of trimetazidine on the heart, not only by metabolism modulation but also by relieving myocardial apoptosis, fibrosis, autophagy, and inflammation. Clinical studies have consistently indicated that trimetazidine acts as an adjunct to conventional treatments and improves the symptoms of heart failure. This review summarizes the basic pathological changes in the myocardium, with an emphasis on the alteration of cardiac metabolism in the development of heart failure. The clinical application of trimetazidine in heart failure and the mechanism of its protective effects on the myocardium are carefully discussed, as well as its main adverse effects. The intention of this review is to highlight this treatment as an effective alternative against heart failure and provide additional perspectives for future studies.

Fulminant myocarditis: a comprehensive review from etiology to treatments and outcomes

Fulminant myocarditis (FM) is characterized by a rapid progressive decline in cardiac function and a high mortality rate. Since the first report of FM patients in the 1980s, several clinical trials and research studies have been published increasing our knowledge regarding FM. Currently, the diagnosis of FM depends on various techniques including electrocardiography, echocardiography, endomyocardial biopsy, and cardiac magnetic resonance. The development of mechanical circulation support (MCS) devices and progress in our understanding of the pathophysiological mechanisms underlying FM, treatment regimens have evolved from simple symptomatic treatment to a life support-based comprehensive treatment approach. The core mechanism underlying the development of FM is the occurrence of an inflammatory cytokine storm. This review provides a comprehensive account of the current understanding of FM pathophysiology and knowledge regarding its etiology, pathophysiology, treatments, and outcomes.

Neuron-Specific Apolipoprotein E4 (1-272) Fragment Induces Tau Hyperphosphorylation and Axonopathy via Triggering Endoplasmic Reticulum Stress

Apolipoprotein (apo) E4 is the major genetic risk factor for Alzheimer's disease (AD). It is shown that apoE4 preferentially undergoes aberrant cleavage in neurons, yielding neurotoxic C-terminal-truncated apoE4 fragment. Endoplasmic reticulum (ER) stress has also been known to be involved in the pathogenesis of AD. However, little is known about the contribution of ER stress to the neurotoxicity of apoE4 fragment. In the present study, we established the neuron-specific expression human C-terminal-truncated apoE4(1-272) fragment transgenic mice and also transfected apoE4(1-272) fragment in neuroblastoma N2a cells. We found that human apoE4(1-272) fragment could trigger ER stress as evidenced by increasing the expression of ER stress markers both in vivo and in vitro. Meanwhile, the apoE4(1-272) transgenic mice presented obviously AD-like neuropathological changes, including the impairment of spatial learning and memory, prominent axonal morphological changes, and hyperphosphorylation of tau. At the same time, we also found that glycogen synthase kinase-3 activities were significantly increased. Furthermore, these neuropathological changes, especially tau hyperphosphorylation and axonal transport impairment, were significantly rescued by the ER stress protector 4-phenylbutyric acid (4-PBA) in apoE4(1-272)-transfected N2a cells. Pretreatment with 4-PBA not only decreased the protein expression of immunoglobulin binding protein (BiP) and C/EBP-homologous protein (CHOP), but also significantly reversed these defects in axonal transport. These results suggested that the neurotoxic effects of apoE4(1-272) fragment found in AD subjects, at least in part, through triggering ER stress and inducing tau hyperphosphorylation, led to the enduring impairment of axonal transport.

The role of CD36 in cardiovascular disease

CD36, also known as the scavenger receptor B2, is a multifunctional receptor widely expressed in various organs. CD36 plays a crucial role in the uptake of long-chain fatty acids, the main metabolic substrate in myocardial tissue. The maturation and transportation of CD36 is regulated by post-translational modifications, including phosphorylation, ubiquitination, glycosylation, and palmitoylation. CD36 is decreased in pathological cardiac hypertrophy caused by ischaemia-reperfusion and pressure overload, and increased in diabetic cardiomyopathy and atherosclerosis. Deficiency of CD36 alleviates diabetic cardiomyopathy and atherosclerosis, while overexpression of CD36 eliminates ischaemia-reperfusion damage, together suggesting that CD36 is closely associated with the progression of cardiovascular diseases and may be a new therapeutic target. This review summarizes the regulation and post-translational modifications of CD36 and evaluates its role in cardiovascular diseases and its potential as a therapeutic target.

[Analysis of correlation between magnetic resonance imaging features and prognosis of invasive pituitary adenoma]

Objective: To explore the application of conventional nuclear magnetic resonance imaging, diffusion-weighted imaging and dynamic contrast-enhanced imaging in invasive pituitary adenoma, and to study the correlation between its imaging features and prognosis. Methods: The imaging manifestations (including T1WI, T2WI, ADC and dynamic contrast-enhanced MR), clinical features and pathological data of 47 cases of invasive pituitary adenomas (IPA) in Tianjin Huanhu Hospital from June 2017 to June 2018 were retrospectively analyzed, and compared with 16 cases of non-invasive pituitary adenoma (NIPA). The differences in tumor/white matter signal intensity ratio on T1WI and T2WI images, MR signs, ADC values and time signal-curve type, peak enhancement time and average enhancement rate between the two groups were observed. Postoperative MR enhanced scan and related hormone results were reviewed to evaluate the prognosis of all patients. Logistic stepwise regression analysis was used to analyze the relationship between IPA imaging characteristics and prognosis. Results: The location, shape, size, Knosp classification and ADC value of tumors were significantly different between IPA and NIPA groups (χ(2) values were 41.344, 21.818, 28.596 respectively, t values were 5.869, 11.720 respectively, all P<0.05). The majority of T1WI, T2WI and enhanced heterogeneous signals occurred in IPA group (P<0.05). IPA showed two-stage enhancement characteristics of rapid enhancement and fast subsidence phase. There were significant differences in peak enhancement time between intrasellar tumors and invasive cavernous sinus tumors. There were no significant differences in signal intensity of T1 and diffusion limitation and two-stage enhancement characteristics between the two groups (all P>0.05). There was a significant correlation between the ratio of tumor body/white matter signal on T2WI, ADC value and the constitution of invasive pituitary tumors (all P<0.05). In IPA, 9 cases(19%) were totally resected, 25 cases(53%) subtotally resected and 13 cases(28%) partially resected. Postoperative symptoms were improved in 29 cases(62%), alleviated in 6 cases(13%), unhealed in 3 cases(6%), assisted drug therapy in 7 cases and radiotherapy in 15 cases. All cases were followed up for 7 to 16 months, with a median time of 12.5 months. Eight cases recurred, with a recurrence rate of 17%. There were significant differences in the total/subtotal resection rate, the improvement rate of symptoms and the need for adjuvant treatment among IPA with different texture (all P<0.05).Knosp grade, tumor size and the ratio of tumor body to white matter on T2WI were associated with IPA recurrence (all P<0.05). Conclusion: It is helpful to diagnose IPA by analyzing the distribution, shape, size, ADC value and signal difference of tumors in sella turcica region through MR and DWI signs. Combined with dynamic contrast enhancement features, the invasion of IPA and its surrounding tissues can be early judged, and the texture of the tumors can be assessed by imaging signs, so as to better evaluate the therapeutic effect and prognosis of IPA.

Cardiac injuries in coronavirus disease 2019 (COVID-19)

As the coronavirus disease 2019 (COVID-19) epidemic worsens, this global pandemic is impacting more than 200 countries/regions and more than 4,500,000 confirmed cases worldwide. COVID-19 is caused by the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), which might attack not only the respiratory system, but also the other important organs, including the heart. It was reported that COVID-19 patients with a past history of cardiovascular diseases would have a higher mortality. Meanwhile, elevated troponin levels were frequently observed in COVID-19 cases. Besides the comprehensive treatments for COVID-19, as a cardiologist, we should also remain vigilant about the cardiac injuries, especially those with severe emergent cardiovascular symptoms.

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Cardiac injury is a common co-morbidity in COVID-19 patients.

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Myocarditis, especially fulminant myocarditis might be also induced by SARS-CoV-2.

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Larger cohorts are required to illustrate the roles of COVID-19 in cardiac injury.

[Magnetic resonance imaging characteristics and differential diagnosis of common sellar cystic lesions]

Objective: To investigate magnetic resonance imaging (MRI) characteristic and differential diagnostic keypoints of common sellar regional cystic lesions with the purpose of improving differential diagnostic accuracy. Methods: In total, 174 cases of the pathologically diagnosed cystic lesions in sellar region between March 2016 and June 2019 were included in the current retrospective analysis. These cases included Rathke's cleft cyst (n=68), craniopharyngioma (n=48), pituitary adenoma (n=56) and arachnoid cyst (n=2) in the sellar region. The position, texture and morphology of leisions, signal of cystic and solid part, invasion of surrounding tissues and maximum diameter of cysts on the MRI images were evaluated and compared between different groups. SPSS 25.0 software was used for statistical analysis. Results: There were several specific changes on several MRI sequences in Rathke's cleft cysts, craniopharyngioma and pituitary adenoma groups. For Rathke's cleft cysts, round shape, rare polycystic structure, lack of solid part and maximum diameter of cysts which was significantly less than that of craniopharyngioma and pituitary adenoma groups ((17.37±6.12) mm vs (30.29±13.51) mm vs (28.18±11.13) mm, t value was 6.680, 5.838, respectively, all P<0.05), were favorable diagnostic criteria. While, the intracystic nodules were mostly found in craniopharyngioma. There was no high signal intensity in cystic wall on T1WI and T2WI of pituitary adenoma. MRI signal of arachnoid cyst in sellar region was basically the same as CSF signal, with low signal intensity on T1WI and DWI, high signal intensity on T2WI, without enhanced signal. Conclusions: Common sellar regional cystic lesions showed characteristic manifestations on different MRI sequences. Valuable information in the morphology, MRI signal intensity, maximum diameter measurements may improve accuracy of differential diagnosis for sellar regional cystic lesions.

Berberine Alleviates Tau Hyperphosphorylation and Axonopathy-Associated with Diabetic Encephalopathy via Restoring PI3K/Akt/GSK3β Pathway

BACKGROUND

Axonopathy is closely linked to the development of diabetic encephalopathy induced by type II diabetes (T2D). Berberine has been shown to cross the blood-brain barrier and holds promising effect for neuronal damage in diabetes.

OBJECTIVE

The present study investigated the protective effect and the underlying mechanism of berberine on neuronal axonopathy in both in vitro and in vivo models.

METHODS

High glucose/high fat diet and streptozotocin injection-induced T2D rat model was used. Berberine was administered p.o. to T2D rat model for 10 weeks. Morris water maze test, in vivo neuronal tracing, immunohistochemistry, and western blot analysis were performed to evaluate the protective effects of berberine in T2D-induced diabetic encephalopathy rats. Primary cultured neurons were used to further explore the underlying mechanisms in vitro.

RESULTS

Berberine dramatically reduced blood glucose and serum insulin levels and alleviated insulin resistance. Berberine significantly attenuated memory impairment, axonopathy, and tau hyperphosphorylation, and also restored PI3K/Akt/GSK3β signaling pathway in T2D rats. In vitro, berberine induced an increase in the phosphorylation of PI3K/Akt as well as GSK3β in high glucose-treated primary neurons. Furthermore, berberine-induced PI3K/Akt activation also resulted in the dephosphorylation of tau protein, which could improve axonal transport impairment in high glucose-treated primary neurons. Pretreated neurons with LY294002, an inhibitor of PI3K, partially blocked berberine-inhibited tau phosphorylation and berberine-activated PI3K/Akt signaling pathway.

CONCLUSIONS

Berberine exerts the protective effect against cognitive deficits by improving tau hyperphosphorylation and the axonal damage through restoring PI3K/Akt/GSK3β signaling pathway.

[Expression of mTOR and 4E-BP1 in extranodal Nasal-type NK/T-cell Lymphoma and implication for prognosis]

Objective: To study the expression of mTOR and 4E-BP1 in extranodal Nasal-type NK/T-cell Lymphoma(ENKTCL) and the correlation with the clinicopathological factors and prognosis of ENKTCL.Method: Immunohistochemistry was used to detect the expresstion of mTOR and 4E-BP1 in the tissues of ENKTCL and nasal pharyngeal lymphoid hyperplasia. The relationship between the expression of mTOR and 4E-BP1 and clinicopathological features was analyzed using the Chi-square test, which including sorting clinical stage, general condition score and international prognostic index(IPI). Result: The expression rates of mTOR and 4E-BP1 in ENKTCL were 63.9% and 58.3% respectively, and significantly higher than those（15.0% and 10.0%）in patients with nasal pharyngeal lymphoid hyperplasia(χ ²=12.355, P=0.0001; χ ²=12.410, P=0.0001). The positive expression rate of mTOR was linked to clinical staging, and the positive protein expressions in Stage Ⅲ and Ⅳwere higher than those in stageⅠand Ⅱ(χ ²=17.902, P=0.0001). mTOR expression was related to 4E-BP1(r=0.655,P=0.001). The positive expression rates of 4E-BP1were linked to IPI of lymphoma(χ ²=4.051, P=0.044). Conclusion: High-expressions of mTOR and 4E-BP1 in patients with ENKTCL are related to the biological progression and recurrence of ENKTCL and are malignant indicators to identify ENKTCL from nasal pharyngeal lymphoid hyperplasia. mTOR and 4E-BP1 may play important roles to assess ENKTCL prognosis..

[Clinical analysis of endoscopic endonasal approach for removal of sellar tumors]

Objective:To investigate the safety and efficacy of endoscopic endonasal approach for removal of sellar tumors. Method: The clinical data of 18 patients with sellar tumors undergoing endoscopic endonasal surgery were analyzed retrospectively. This series consisted of ten pituitary adenomas, five craniopharyngiomas, three meningiomas. The headache, visual improvement, endocrine, extent of resection and surgical complications were evaluated. Result:Total removal was achieved in 14 patients (77.8%), almost total removal was achieved in one patient of pituitary adenoma with two craniopharyngiomas (16.7%), and one patient with the subtotal removal of craniopharyngioma (5.6%) received gamma knife therapy. Overall, 18 patients with headache got improved obviously; 15 patients presented with visual and view impairment, All of them, vision and view were improved or even recovered to normal following surgery; There were 2 new cases of postoperative diabetes insipidu; 5(27.8%) patients had hyposmia after operation; 1 patient (5.6%) with adenoma suffered cerebrospinal fluid rhinorrhea, the second operation was successful. The follow-up lasted 12-84 months, no tumor recurrence was identified by MRI examination, and no patient died. Conclusion:The endoscopic endonasal approach is feasible and safe for the treatment of tumors in the sellar region. With advantages of clear vision, better exposure, without brain retraction, and preservation of vascular and neurological function. Skilled endoscopic technique and reliable skull base reconstruction are important to ensure success of surgery.

Berberine Ameliorates High Glucose-Induced Cardiomyocyte Injury via AMPK Signaling Activation to Stimulate Mitochondrial Biogenesis and Restore Autophagic Flux

Background: Type II diabetes (T2D)-induced cardiomyocyte hypertrophy is closely linked to the impairment of mitochondrial function. Berberine has been shown to be a promising effect for hypoglycemia in T2D models. High glucose-induced cardiomyocyte hypertrophy in vitro has been reported. The present study investigated the protective effect and the underlying mechanism of berberine on high glucose-induced H9C2 cell line.

Methods: High glucose-induced H9C2 cell line was used to mimic the hyperglycemia resulting in cardiomyocyte hypertrophy. Berberine was used to rescue in this model and explore the mechanism in it. Confocal microscopy, immunofluorescence, RT-PCR, and western blot analysis were performed to evaluate the protective effects of berberine in high glucose-induced H9C2 cell line.

Results: Berberine dramatically alleviated hypertrophy of H9C2 cell line and significantly ameliorated mitochondrial function by rectifying the imbalance of fusion and fission in mitochondrial dynamics. Furthermore, berberine further promoted mitogenesis and cleared the damaged mitochondria via mitophagy. In addition, berberine also restored autophagic flux in high glucose-induced cardiomyocyte injury via AMPK signaling pathway activation.

Conclusion: Berberine ameliorates high glucose-induced cardiomyocyte injury via AMPK signaling pathway activation to stimulate mitochondrial biogenesis and restore autophagicflux in H9C2 cell line.

[Olfactory functional magnetic resonance imaging in patients with mild cognitive impairment]

Objective: To analyze the activation of brain regions associated with olfactory in patients with mild cognitive impairment (MCI) by olfactory functional magnetic resonance imaging (fMRI). Methods: Twenty six patients with MCI were compared with twenty six controls in the dementia center of Tianjin HuanHu hospital in terms of olfactory function T&T testing, the differences between the activation of the whole brain and region of interest associated with olfactory (bilateral primary olfactory cortex(POC), bilateral hippocampus, bilateral orbital frontal gyrus) by olfactory stimulator using event correlation design for olfactory fMRI scanning. To analyze the correlation between the number of activator in POC and the threshold of olfactory discriminate as well as the severity of cognitive impairment.SPSS 19.0 software was used for the statistical analysis. Results: T&T olfactory testing revealed that MCI patients had higher scores than controls (3.57±1.29 (x±s) vs 1.02±0.35, t=4.372, P<0.05). The activation range of whole brain in MCI patients was less than controls (pleasant odor (po) 147.36±21.45 vs 323.11±39.76, unpleasant odor (upo) 201.86±24.93 vs 447.73±57.22, t(po)=4.241, t(upo)=5.365, both P<0.05). The activation range of whole brain in inhaling unpleasant odor was more than pleasant odor in controls (447.73±57.22 vs 323.11±39.76, t=3.936, P<0.05). The number of activator in ROI(awo) in MCI patients was less than controls (pleasant odor (po) 51.0[8.0, 109.0](M[P(25), P(75)]) vs 135.0[21.0, 321.5], unpleasant odor (upo) 65.0[6.0, 158.0]vs 205.0[36.5, 491.0], Z(po)=-2.199, Z(upo)=-2.216, both P<0.05). The number of activator in POC in MCI patients was less than controls (pleasant odor (po) 19.0[4.0, 35.5]vs 46.0[9.0, 118.5], unpleasant odor (upo) 26.0[2.0, 51.0]vs 79.0[17.5, 189.0], Z(po)=-1.898, Z(upo)=-2.167, both P<0.05). The number of activator in POC was negatively correlated with olfactory discriminate threshold in MCI patients (r(po)=-0.415, r(upo)=-0.409, both P<0.05). The number of activator in POC was positively correlated with MoCA in MCI patients (r(po)=0.289, r(upo)=0.296, both P<0.05). Conclusion: Olfactory fMRI can objectively assess the olfactory function in MCI, it is a imaging indicator with neuropsychological tests for detection in MCI, the number of activator in POC can reflect the severity of MCI.

SAC-1 ensures epithelial endocytic recycling by restricting ARF-6 activity

Arf6/ARF-6 is a crucial regulator of the endosomal phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) pool in endocytic recycling. To further characterize ARF-6 regulation, we performed an ARF-6 interactor screen in Caenorhabditis elegans and identified SAC-1, the homologue of the phosphoinositide phosphatase Sac1p in yeast, as a novel ARF-6 partner. In the absence of ARF-6, basolateral endosomes show a loss of SAC-1 staining in epithelial cells. Steady-state cargo distribution assays revealed that loss of SAC-1 specifically affected apical secretory delivery and basolateral recycling. PI(4,5)P2 levels and the endosomal labeling of the ARF-6 effector UNC-16 were significantly elevated in sac-1 mutants, suggesting that SAC-1 functions as a negative regulator of ARF-6. Further analyses revealed an interaction between SAC-1 and the ARF-6-GEF BRIS-1. This interaction outcompeted ARF-6(guanosine diphosphate [GDP]) for binding to BRIS-1 in a concentration-dependent manner. Consequently, loss of SAC-1 promotes the intracellular overlap between ARF-6 and BRIS-1. BRIS-1 knockdown resulted in a significant reduction in PI(4,5)P2 levels in SAC-1-depleted cells. Interestingly, the action of SAC-1 in sequestering BRIS-1 is independent of SAC-1's catalytic activity. Our results suggest that the interaction of SAC-1 with ARF-6 curbs ARF-6 activity by limiting the access of ARF-6(GDP) to its guanine nucleotide exchange factor, BRIS-1.

Melatonin Mitigates Kainic Acid-Induced Neuronal Tau Hyperphosphorylation and Memory Deficits through Alleviating ER Stress

Kainic acid (KA) exposure causes neuronal degeneration featured by Alzheimer-like tau hyperphosphorylation and memory deficits. Melatonin (Mel) is known to protect hippocampal neurons against KA-induced damage. However, the underlying mechanisms remain elusive. In the current study, we investigated the protective effect of melatonin on KA-induced tau hyperphosphorylation by focusing on endoplasmic reticulum (ER) stress-mediated signaling pathways. By using primary hippocampal neurons and mouse brain, we showed that KA treatment specifically induced ER stress and activated GSK-3β and CDK5, two major kinases responsible for tau phosphorylation. Inhibition of ER stress efficiently inactivated GSK-3β and CDK5. Mechanistically, we found that KA-induced ER stress significantly activated calpain, a calcium-dependent protease. Inhibition of ER stress or calpain leads to the reduction in KA-induced GSK-3β and CDK5 activities and tau phosphorylation. Moreover, GSK-3β or CDK5 inhibition failed to downregulate ER stress efficiently, suggesting that ER stress functions upstream of GSK-3β or CDK5. Notably, our results revealed that melatonin acts against KA-induced neuronal degeneration and tau hyperphosphorylation via easing ER stress, further highlighting the protective role of melatonin in the KA-induced neuronal defects.

LET-413/Erbin acts as a RAB-5 effector to promote RAB-10 activation during endocytic recycling

RAB-10 is a master regulator of endocytic recycling in polarized epithelial cells. Liu et al. identify LET-413, the Caenorhabditis elegans homolog of Scrib/Erbin, as a RAB-5 effector that is required for the DENN-4–mediated activation of RAB-10 and the control of membrane expansion in the C. elegans intestine.

RAB-10/Rab10 is a master regulator of endocytic recycling in epithelial cells. To better understand the regulation of RAB-10 activity, we sought to identify RAB-10(GDP)–interacting proteins. One novel RAB-10(GDP)–binding partner that we identified, LET-413, is the Caenorhabditis elegans homologue of Scrib/Erbin. Here, we focus on the mechanistic role of LET-413 in the regulation of RAB-10 within the C. elegans intestine. We show that LET-413 is a RAB-5 effector and colocalizes with RAB-10 on endosomes, and the overlap of LET-413 with RAB-10 is RAB-5 dependent. Notably, LET-413 enhances the interaction of DENN-4 with RAB-10(GDP) and promotes DENN-4 guanine nucleotide exchange factor activity toward RAB-10. Loss of LET-413 leads to cytosolic dispersion of the RAB-10 effectors TBC-2 and CNT-1. Finally, we demonstrate that the loss of RAB-10 or LET-413 results in abnormal overextensions of lateral membrane. Hence, our studies indicate that LET-413 is required for DENN-4–mediated RAB-10 activation, and the LET-413–assisted RAB-5 to RAB-10 cascade contributes to the integrity of C. elegans intestinal epithelia.

[Immune checkpoint inhibitor therapy in advanced head and neck cancer]

Immune checkpoint inhibitor therapy, which targets regulatory pathways in T cells to enhance antitumor immune responses, improves the life quality of cancer patients and has joined the ranks of surgery, radiation, and chemotherapy to become a major choice for cancer therapy. Over the past few years, multiple exciting results have been obtained on checkpoint inhibitor therapy in advanced head and neck cancer. However, questions such as patient selection and biomarkers for assessing the therapy are largely unsolved. Herein, we briefly review recent findings in checkpoint inhibitor therapy for advanced head and neck cancer. We will also discuss possible mechanism, safety, combination therapy, and side effects for the therapy. Checkpoint inhibitor therapy has led to important clinical advances and will provide a new weapon against cancer.

Melatonin Mediates Protective Effects against Kainic Acid-Induced Neuronal Death through Safeguarding ER Stress and Mitochondrial Disturbance

Kainic acid (KA)-induced neuronal death is linked to mitochondrial dysfunction and ER stress. Melatonin is known to protect hippocampal neurons from KA-induced apoptosis, but the exact mechanisms underlying melatonin protective effects against neuronal mitochondria disorder and ER stress remain uncertain. In this study, we investigated the sheltering roles of melatonin during KA-induced apoptosis by focusing on mitochondrial dysfunction and ER stress mediated signal pathways. KA causes mitochondrial dynamic disorder and dysfunction through calpain activation, leading to neuronal apoptosis. Ca²⁺ chelator BAPTA-AM and calpain inhibitor calpeptin can significantly restore mitochondrial morphology and function. ER stress can also be induced by KA treatment. ER stress inhibitor 4-phenylbutyric acid (PBA) attenuates ER stress-mediated apoptosis and mitochondrial disorder. It is worth noting that calpain activation was also inhibited under PBA administration. Thus, we concluded that melatonin effectively inhibits KA-induced calpain upregulation/activation and mitochondrial deterioration by alleviating Ca²⁺ overload and ER stress.

Speciation of gold(III)-L-histidine complex: a multi-instrumental approach

The formation and structure of gold (III)-L-histidine complex was investigated with the use of carbon (13C) and proton (1H) nuclear magnetic resonance (NMR), infrared (IR) spectroscopy, capillary electrophoresis (CE), capillary electrophoresis-inductively coupled plasma-mass spectroscopy (CE-ICP-MS), X-ray fluorescence spectroscopy (XRF), matrix-assisted laser desorption/ionization (MALDI), and laser desorption mass spectroscopy (LDMS). It was found that two L-histidine molecules and one gold ion slowly form a complex in acidic solution. Each L-histidine molecule provided two nitrogen ligands; one was the alpha-amino group and the other from the imidazole ring. The Au(III)-bis-L-histidine complex precipitates after deprotonation of the free carboxylic group, resulting in an increase in the solution acidity. Determination of the exact sequence of events and the identity of the complex was a comprehensive instrumental analysis problem involving the above techniques.

Powering the analytical glow discharge

The glow discharge may be powered by direct current (dc), radio frequency (rf) and pulsed discharge sources. Each has specific advantages and special features that should be considered by analysts using the various forms of glow discharge spectroscopy. This paper reviews some of the factors that contribute to the selection of a power source for the glow discharge.

Microsecond-pulse glow discharge atomic emission

A microsecond pulsed glow discharge was produced with high pulse magnitude and small duty cycle. Time resolved emission and absorption spectroscopy was applied to study the processes of atomization, excitation and ionization in the glow discharge. Experimental results show that, without overheating the sample, the emission peak intensity is several orders greater than that obtained in the conventional dc mode. This implies that a much more intense plasma is generated during pulsed "on" region.