MiR-29 inhibits neuronal apoptosis in rats with cerebral infarction through regulating Akt signaling pathway

OBJECTIVE

The aim of this study was to explore the influence of micro ribonucleic acid (miR)-29 on neuronal apoptosis in rats with cerebral infarction by regulating the protein kinase B (Akt) signaling pathway.

MATERIALS AND METHODS

A total of 36 Sprague-Dawley rats were randomly divided into three groups, including: Sham group (n=12), Model group (n=12), and Inhibitor group (n=12). Common carotid artery, external carotid artery, and internal carotid artery were only exposed in the Sham group. However, the ischemia-reperfusion model was established by the suture method in the other two groups. After modeling, artificial cerebrospinal fluid was injected into the lateral ventricle in the rats of the Sham and Model groups. Similarly, miR-29 inhibitor was injected into the lateral ventricle in the rats of the Inhibitor group. At 24 h postoperatively, the sampling was performed. Zea-Longa score was used to evaluate the neurological deficit of rats. Meanwhile, the expressions of B-cell lymphoma 2 (Bcl-2) and Bcl-2 associated X protein (Bax) in cerebral tissues were detected via immunohistochemistry. The protein expression levels of Akt and phosphorylated Akt (p-Akt) were determined using Western blotting. Furthermore, the expression of miR-29 and cell apoptosis were detected via quantitative Polymerase Chain Reaction (qPCR) and terminal deoxynucleotidyl transferase (TdT) dUTP nick-end labeling (TUNEL) assay, respectively.

RESULTS

Compared with Sham group, Model, and Inhibitor groups had substantially raised the Zea-Longa scores (p<0.05). The Zea-Longa score in the Model group was markedly lower than that of the Inhibitor group (p<0.05). The positive expression level of Bax was remarkably upregulated (p<0.05). However, the positive expression level of Bcl-2 declined dramatically in both Model group and Inhibitor group when compared with the Sham group (p<0.05). Besides, the Model group exhibited significantly lower positive expression level of Bax and higher positive expression level of Bcl-2 than the Inhibitor group (p<0.05). The relative protein expression level of p-Akt markedly increased in the Model and Inhibitor groups when compared with the Sham group (p<0.05). However, it was considerably higher in the Model group than that of the Inhibitor group (p<0.05). In comparison with the Sham group, both Model group and Inhibitor group exerted substantially elevated expression level of miR-29 (p<0.05). The relative expression level of miR-29 in the Model group was significantly upregulated when compared with the Inhibitor group (p<0.05). The apoptosis rate of cells in both Model group and Inhibitor group was markedly higher than that of the Sham group (p<0.05). Furthermore, the Model group showed remarkably lower apoptosis rate than the Inhibitor group (p<0.05).

CONCLUSIONS

MiR-29 inhibits neuronal apoptosis in cerebral infarction rats by upregulating the Akt signaling pathway, thereby serving as a protector.

Prognostic impact of baseline tumour immune infiltrate on disease-free survival in patients with completely resected, BRAFv600 mutation-positive melanoma receiving adjuvant vemurafenib

BACKGROUND

We conducted a retrospective exploratory analysis to evaluate the effects of baseline tumour immune infiltrate on disease-free survival (DFS) outcomes in patients with fully resected stage IIC-IIIC melanoma receiving adjuvant vemurafenib monotherapy or placebo in the BRIM8 study.

PATIENTS AND METHODS

BRIM8 was a phase III, international, double-blind, randomised, placebo-controlled study. Eligible patients with BRAF^V600 mutation-positive, completely resected melanoma were randomly assigned to oral vemurafenib (960 mg twice daily) or matching placebo for 52 weeks. The primary end point was DFS. The association of CD8+ T-cell infiltration and programmed death ligand 1 (PD-L1) expression with DFS, as measured by immunohistochemistry, was explored retrospectively.

RESULTS

Four hundred ninety-eight patients were randomly assigned to receive adjuvant vemurafenib (n = 250) or placebo (n = 248); tumour samples were available for biomarker analysis for approximately 60% of patients. In the pooled biomarker population, placebo-treated patients with <1% CD8+ T cells in the tumour centre had shorter median DFS than those with ≥1% CD8+ T cells (7.7 versus 47.8 months). DFS benefit from vemurafenib versus placebo was greater in patients with <1% CD8+ T cells [hazard ratio (HR) 0.56; 95% confidence interval (CI) 0.34-0.92) than in patients with ≥1% CD8+ T cells (HR 0.77; 95% CI 0.48-1.22). Likewise, median DFS was shorter among placebo-treated patients with <5% versus ≥5% PD-L1+ immune cells (IC) in the tumour (7.2 versus 47.8 months). A greater DFS benefit with vemurafenib versus placebo was observed in patients with <5% PD-L1+IC (HR 0.36; 95% CI 0.24-0.56) than in patients with ≥5% PD-L1+IC (HR 0.99; 95% CI 0.58-1.69).

CONCLUSIONS

The presence of CD8+ T cells and PD-L1+IC are favourable prognostic factors for DFS. Treatment with adjuvant vemurafenib may overcome the poor DFS prognosis associated with low CD8+ T-cell count or PD-L1 expression. CLINICALTRIALS.

GOV IDENTIFIER

NCT01667419.

Cobimetinib plus atezolizumab in BRAFV600 wild-type melanoma: primary results from the randomized phase III IMspire170 study

BACKGROUND

Emerging data suggest that the combination of MEK inhibitors and immunotherapeutic agents may result in improved efficacy in melanoma. We evaluated whether combining MEK inhibition and immune checkpoint inhibition was more efficacious than immune checkpoint inhibition alone in patients with previously untreated BRAF^V600 wild-type advanced melanoma.

PATIENTS AND METHODS

IMspire170 was an international, randomized, open-label, phase III study. Patients were randomized 1 : 1 to receive cobimetinib (60 mg, days 1-21) plus anti-programmed death-ligand 1 atezolizumab (840 mg every 2 weeks) in 28-day cycles or anti-programmed death-1 pembrolizumab (200 mg every 3 weeks) alone until loss of clinical benefit, unacceptable toxicity, or consent withdrawal. The primary outcome was progression-free survival (PFS), assessed by an independent review committee in the intention-to-treat population.

RESULTS

Between 11 December 2017, and 29 January 2019, 446 patients were randomized to receive cobimetinib plus atezolizumab (n = 222) or pembrolizumab (n = 224). Median follow-up was 7.1 months [interquartile range (IQR) 4.8-9.9] for cobimetinib plus atezolizumab and 7.2 months (IQR 4.9-10.1) for pembrolizumab. Median PFS was 5.5 months [95% confidence interval (CI) 3.8-7.2] with cobimetinib plus atezolizumab versus 5.7 months (95% CI 3.7-9.6) with pembrolizumab [stratified hazard ratio 1.15 (95% CI 0.88-1.50); P = 0.30]. Hazard ratios for PFS were consistent across prespecified subgroups. In exploratory biomarker analyses, higher tumor mutational burden was associated with improved clinical outcomes in both treatment arms. The most common grade 3-5 adverse events (AEs) were increased blood creatine phosphokinase (10.0% with cobimetinib plus atezolizumab versus 0.9% with pembrolizumab), diarrhea (7.7% versus 1.9%), rash (6.8% versus 0.9%), hypertension (6.4% versus 3.7%), and dermatitis acneiform (5.0% versus 0). Serious AEs occurred in 44.1% of patients with cobimetinib plus atezolizumab and 20.8% with pembrolizumab.

CONCLUSION

Cobimetinib plus atezolizumab did not improve PFS compared with pembrolizumab monotherapy in patients with BRAF^V600 wild-type advanced melanoma.

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is associated with IRF7, BANK1 and TBX21 polymorphisms in two populations

BACKGROUND AND PURPOSE

Autoantibodies targeting the GluN1(NR1) subunit of the anti-N-methyl-D-aspartate receptor (NMDAR) cause encephalitis. Although it has been shown that anti-NMDAR encephalitis is associated with human leukocyte antigen (HLA) loci, susceptibility genes for the disease outside the HLA loci remain unidentified. In this study, we aimed to explore the association of anti-NMDAR encephalitis with non-HLA genes.

METHODS

Two Chinese anti-NMDAR encephalitis cohorts from Han populations were recruited for this study. The North Chinese case-control set consisted of 98 patients and 460 controls, while the South Chinese case-control set included 78 patients and 541 controls. All participants were genotyped for 28 single nucleotide polymorphisms that are associated with autoimmune disorders or infectious diseases.

RESULTS

In two independent case-control sets, we identified significant associations of anti-NMDAR encephalitis with IRF7 rs1131665 (odds ratio [OR] 3.34, 95% confidence interval [CI] 1.99-5.63; P < 0.000001, P^adjusted  = 0.00004), BANK1 rs4522865 (OR 1.44, 95% CI 1.15-1.82; P = 0.0017, P^adjusted  = 0.0149), and TBX21 rs17244587 (OR 2.03, 95% CI 1.35-3.05; P = 0.00051, P^adjusted  = 0.0066). Furthermore, analysis of the three polymorphisms with clinical features of the disease revealed that the IRF7 rs1131665 was associated with tumor status.

CONCLUSION

The present study has for the first time identified non-HLA susceptibility genes for anti-NMDAR encephalitis. The association of IRF7, BANK1 and TBX21 with anti-NMDAR encephalitis suggests that B-cell activation, Th1 responses, virus infection and the type I interferon signaling pathway are involved in the pathogenesis of the disease.

Association of placenta-derived extracellular vesicles with pre-eclampsia and associated hypercoagulability: a clinical observational study

OBJECTIVE

Pre-eclampsia (PE) is a pregnancy-associated condition initiated by placental factors. We have demonstrated that placental extracellular vesicles (pcEVs) cause hypertension and proteinuria in pregnant and non-pregnant mice.

STUDY DESIGN

An observational study with both case-control and longitudinal designs.

SETTING

A single centre at the Department of Obstetrics and Gynaecology, Tianjin Medical University.

POPULATION

We collected blood samples and clinical information from 54 PE patients, 33 normally pregnant women at 30-36 gestational weeks and on postpartum days 1 and 4 for the cross-sectional study, and at 22-31, 32-35 and 36-40 weeks for the longitudinal study. Non-pregnant women were also recruited.

METHODS

Blood samples were analysed using flow cytometry, coagulation tests and ELISA.

MAIN OUTCOME MEASURES

The primary outcome was plasma pcEV and other extracellular vesicles (EVs), and their expressions of anionic phospholipids and von Willebrand factor (VWF). Secondary variables included coagulation, ADAMTS-13 and the anionic phospholipid-binding proteins.

RESULTS

Plasma pcEVs progressively increased from pregnant women during non-menstrual period (NW) to PE patients (interquartile range [IQR] for NW: 206/microlitre [116-255], normal pregnancy [NP]: 1108/microlitre [789-1969] and PE: 8487/microlitre [4991-16 752]) and predicted PE. EVs from endothelial cells, platelets and erythrocytes accounted for <10% of pcEVs. VWF became hyper-adhesive in PE patients and contributed to the pregnancy-associated hypercoagulability.

CONCLUSION

Placental, platelet- and endothelial cell-derived EVs were significantly elevated in PE patients, but only pcEVs predicted PE. These EVs played a causal role in the pregnancy-induced hypercoagulability.

TWEETABLE ABSTRACT

Placenta-derived extracellular vesicles predict pre-eclampsia and the associated hypercoagulability.

Cardioprotection by remote ischemic conditioning is transferable by plasma and mediated by exosomes

Background

Remote ischemic conditioning (RIC) by brief periods of limb ischemia and reperfusion protects against ischemia-reperfusion injury. However, the mechanism is unknown.

Purpose

We studied the role of exosomes for mediating the cardioprotective signal and whether they accumulate in injured myocardium.

Methods

Blood samples from 12 healthy male volunteers were obtained prior to and one hour after RIC. Plasma obtained before and after RIC (n=4) (P-Pre and P-Post) was used to evaluate the transferability of RIC. Pre- and Post-RIC plasma (n=8) was separated into an exosome rich fraction (Exo-Pre and Exo-Post) and an exosome depleted fraction (Prot-Pre and Prot-Post) by size exclusion chromatography. All studies were carried out in duplicate samples from each volunteer. Infarct size was compared in Sprague-Dawley rat hearts perfused with plasma, exosomes and exosome depleted fractions in a Langendorff model. We investigated changes in the miRNA content of the exosomes after RIC by a human miRNA panel. Additionally, fluorescently labeled exosomes isolated from C2C12 cells were used to assess accumulation in injured myocardium in an in vivo rat model. Rats were divided into an infarct group (n=6) (left anterior descending artery ligation) and a sham group (n=6) (without ligation). Labelled exosomes were injected in the femoral vein prior to reperfusion. Exosome-accumulation in infarcted or sham myocardium was evaluated.

Results

P-Post reduced infarct size by 15% points compared with P-Pre (55±4% vs 70±6%, p=0.03) (Fig. 1a). Exo-Post reduced infarct size by 16% points compared with Exo-Pre (53±15% vs 68±12%, p=0.03) (Fig. 1b). Prot-Post did not affect infarct size compared to Prot-Pre (64±3% and 68±10%, p&gt;0.99). We found miRNA-16, miRNA-144 and miRNA-451 to be upregulated in exosomes after RIC and the mTOR-pathway as a potential target for these miRNAs. In the in vivo model, labelled exosomes accumulated more intensively in the infarct area than in remote areas and sham hearts (Fig. 1c).

Conclusion

Cardioprotection by RIC is mediated by exosomes with a changed miRNA profile and exosomes accumulate in injured myocardium.

Figure 1

Funding Acknowledgement

Type of funding source: Private company. Main funding source(s): Novo synergy

A study on regulatory mechanism of miR-223 in ulcerative colitis through PI3K/Akt-mTOR signaling pathway

OBJECTIVE

The aim of this study was to explore the regulatory mechanism of micro ribonucleic acid (miR)-223 in ulcerative colitis (UC) through the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt)-mammalian target of rapamycin (mTOR) signaling pathway.

MATERIALS AND METHODS

A total of 36 Sprague-Dawley (SD) rats were randomly divided into three groups, including normal group (n=12), model group (n=12) and inhibitor group (n=12). Rats in the normal group received no treatment. Rats in the model group were used to establish a UC model. Meanwhile, rats in the inhibitor group underwent intraperitoneal injection of inhibitor and establishment of the UC model. Subsequently, specimens were obtained for detection. Immunohistochemistry was applied to measure the expression of mTOR. Western blotting was adopted to determine the relative protein expressions of P85, P110 and phosphorylated Akt (p-Akt). Quantitative polymerase chain reaction (qPCR) was used to detect the mRNA expression of miR-223. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) was utilized to determine cell apoptosis. Furthermore, an enzyme-linked immunosorbent assay (ELISA) was conducted to measure the content of interleukin-1 beta (IL-1β) and IL-6.

RESULTS

Immunohistochemistry showed that the positive expression of mTOR increased remarkably in the model group and inhibitor group when compared with that of the normal group (p<0.05). However, it decreased notably in the inhibitor group when compared with the model group (p<0.05). Western blotting indicated that the protein expressions of P85, P110 and p-Akt in model group and inhibitor group were significantly higher than the ones of the normal group (p<0.05). However, the inhibitor group showed markedly lower relative protein expressions of P85, P110 and p-Akt than the ones of the model group (p<0.05). Compared with the normal group, the expression level of miR-223 was significantly elevated in model group and inhibitor group (p<0.05). However, there was no significant difference in the mRNA expression of miR-233 between the model group and the inhibitor group (p>0.05). The apoptosis rate of the cells increased prominently in the model group and in the inhibitor group when compared with the normal group (p<0.05). However, it was remarkably reduced in the inhibitor group than the model group (p<0.05). In comparison with the normal group, the content of IL-1β and IL-6 was significantly up-regulated in the model group and in the inhibitor group (p<0.05). However, it declined notably in the inhibitor group compared with the model group (p<0.05).

CONCLUSIONS

MiR-223 can trigger cell apoptosis and inflammation in UC by up-regulating the PI3K/Akt-mTOR signaling pathway.

Efficacy of laparoscopic gastric bypass vs laparoscopic sleeve gastrectomy in treating obesity combined with type-2 diabetes

OBJECTIVE

This prospective study compared the efficacy and safety of laparoscopic gastric bypass and laparoscopic sleeve gastrectomy in treating overweight and obese patients with BMI>28 kg/m² and type-2 diabetes.

METHODS

Patients were randomized into a gastric bypass group (n = 77) or a gastrectomy group (n = 80). The surgery time, intraoperative blood loss, recovery time, and hospitalization time were collected. BMI, waistline, hipline, C-peptide level, insulin resistance index (HOMA-IR), and their blood and lipid profile were also measured.

RESULTS

Surgery time and blood loss were significantly higher in the gastrectomy group, when compared to the gastric bypass group (P < 0.05). In both groups, the levels of BMI, waist circumference and hip circumference (but not their ratio) gradually and significantly decreased after surgery compared with baseline (P < 0.05), and no significant difference was found between these two groups. The C-peptide level, HOMA-IR, fasting blood glucose, 2-hour postprandial blood glucose and glycosylated haemoglobin gradually and significantly decreased after surgery compared with the values before treatment (P < 0.05). The levels of total cholesterol, triglyceride, LDL, and monocyte chemoattractant protein-1 were also lower after surgery in both groups, while HDL and glucagon-like peptide-1 were significantly higher after surgery compared with the values before treatment (P < 0.05). However, no significant difference was found between these two groups of patients.

CONCLUSION

Both laparoscopic gastric bypass and laparoscopic sleeve gastrectomy improved the BMI and diabetic conditions of overweight/obese diabetics, while laparoscopic sleeve gastrectomy had a shorter surgical time and less blood loss.

Functionally weighted airway sparing (FWAS): a functional avoidance method for preserving post-treatment ventilation in lung radiotherapy

Recent changes to the guidelines for screening and early diagnosis of lung cancer have increased the interest in preserving post-radiotherapy lung function. Current investigational approaches are based on spatially mapping functional regions and generating regional avoidance plans that preferentially spare highly ventilated/perfused lung. A potentially critical, yet overlooked, aspect of functional avoidance is radiation injury to peripheral airways, which serve as gas conduits to and from functional lung regions. Dose redistribution based solely on regional function may cause irreparable damage to the 'supply chain'. To address this deficiency, we propose the functionally weighted airway sparing (FWAS) method. FWAS (i) maps the bronchial pathways to each functional sub-lobar lung volume; (ii) assigns a weighting factor to each airway based on the relative contribution of the sub-volume to overall lung function; and (iii) creates a treatment plan that aims to preserve these functional pathways. To evaluate it, we used four cases from a retrospective cohort of SAbR patients treated for lung cancer. Each patient's airways were auto-segmented from a diagnostic-quality breath-hold CT using a research virtual bronchoscopy software. A ventilation map was generated from the planning 4DCT to map regional lung function. For each terminal airway, as resolved by the segmentation software, the total ventilation within the sub-lobar volume supported by that airway was estimated and used as a function-based weighting factor. Upstream airways were weighted based on the cumulative volumetric ventilation supported by corresponding downstream airways. Using a previously developed model for airway radiosensitivity, dose constraints were determined for each airway corresponding to a <5% probability of airway collapse. Airway dose constraints, ventilation scores, and clinical dose constraints were input to a swarm optimization-based inverse planning engine to create a 3D conformal SAbR plan (CRT). The FWAS plans were compared to the patients' prescribed CRT clinical plans and the inverse-optimized clinical plans. Depending on the size and location of the tumour, the FWAS plan showed superior preservation of ventilation due to airflow preservation through open pathways (i.e. cumulative ventilation score from the sub-lobar volumes of open pathways). Improvements ranged between 3% and 23%, when comparing to the prescribed clinical plans, and between 3% and 35%, when comparing to the inverse-optimized clinical plans. The three plans satisfied clinical requirements for PTV coverage and OAR dose constraints. These initial results suggest that by sparing pathways to high-functioning lung subregions it is possible to reduce post-SAbR loss of respiratory function.

[Investigation of the screening interval for population with negative colonoscopy examinations]

Objective: To investigate the colonscopy screening interval among patients with negative colonscopy. Methods: We selected 14 606 participants who completed the baseline and 3-year or 5-year colonoscopy examinations in the American Prostate, Lung, Colorectal, and Ovarian (PLCO) dataset as the target population. Sociodemographic characteristics (i.e., sex, age, marital status, race, and smoking), lifestyle, family history of cancer, and family history of colorectal cancer were collected. Cochran-Armitage trend analysis was used to examine whether the rate of positive cases (colorectal cancer, advanced adenoma, adenoma, and hyperplastic polyp) was increased with the length of screening interval. We compared the differences in number of detected cases, positive rates, and proportions of 3-year and 5-year screening interval strategies using internal standardization method. Results: The age of the population was （61.9±5.2） years and over half of them were males (54.4%) and 46.2% had family cancer history. The mean screening interval between the first and second endoscopies was （1 639.1±320.9） days. A total of 1 716 cases had positive endoscopic findings. With the screening interval extended, rate of the screened positive cases was also increased (P _{for trend}<0.001). After standardized by the internal standardized population (14 606), 17.99 and 11.57 colorectal cancer cases and 177.37 and 240.35 advanced adenoma cases were detected by 3-year and 5-year screening interval strategies, respectively. Conclusion: Based on the initial screening negative population of colonoscopy in the United States, the 3-year screening interval strategy could detect a relatively large number of colorectal cancer cases, but its health and economic evaluation needs to be further explored.

Clinical significance of expression level of CX3CL1-CX3CR1 axis in bone metastasis of lung cancer

PURPOSE

To investigate the clinical significance of CX3 chemokine ligand 1(CX3CL1) and CX3CR1 in patients with bone metastasis from lung cancer. The expression levels of CX3CL1 and CX3CR1 mRNA and protein in primary lung cancer and lung cancer bone metastasis were detected by qRT-PCR and Western blot.

METHODS

One hundred patients with lung cancer were divided into a boneless metastasis group (50 patients with bone metastasis) and a bone metastasis group (50 patients without distant metastasis). The bone transfer component was graded by Soloway classification (0 to III). The expression levels of serum CX3CL1-CX3CR1 axis were detected by enzyme-linked immunosorbent assay (ELISA). RT-qPCR and Western Blot were used to verify the transfection efficiency. The scratching assay was used to detect the migration of CX3CL1 to 95-D cells after down-regulating the expression of CX3CR1.

RESULTS

The expression levels of CX3CL1 and CX3CR1 mRNA and protein in the primary lung cancer and lung cancer bone metastasis were significantly higher than those in the adjacent tissues (P < 0.0001). The levels of serum CX3CL1 and CX3CR1 in bone metastasis group were significantly higher than those in boneless metastasis group and healthy control group (P < 0.05). In the bone metastasis group, the levels of serum CX3CL1 and CX3CR1 were significantly positively correlated with the degree of disease progression (P < 0.01).

CONCLUSION

The expression level of serum CX3CL1-CX3CR1 axis is expected to be an auxiliary reference index for monitoring bone metastasis of lung cancer.

The importance of proper and prompt treatment of ocular syphilis: a lesson from permanent vision loss in 52 eyes

BACKGROUND

Ocular involvement can occur at any stage of syphilis. Prompt diagnosis and proper treatment of ocular syphilis are vital to avoid long-term consequences.

OBJECTIVES

To describe the risk factors for ocular syphilis and clinical features of blindness caused by syphilis.

METHODS

We report risk factors for ocular syphilis amongst patients seen at the Shanghai Skin Disease Hospital between October 2009 and October 2017. We identify patients with ocular syphilis resulting in blindness and report the clinical characteristics, laboratory findings and treatment outcomes of these patients.

RESULTS

A total of 8310 new cases of syphilis were seen, of which 213 patients had ocular disease and 50 patients had blindness due to syphilis. Increasing age and higher RPR titres were associated with ocular involvement but there was no association with HIV status. Blindness in syphilis was restricted predominantly to patients with optic nerve involvement and not patients with isolated uveitis. Fifty patients (and a total of 67 eyes) met the WHO definition of blindness prior to treatment for syphilis. At the end of follow-up, vision had improved in 24 of 67 eyes (35.8%) after treatment. Successful treatment of uveitis was associated with the best improvement in visual acuity, whilst patient with underlying optic atrophy prior to treatment had the worst visual outcome.

CONCLUSIONS

Ocular involvement is an important manifestation of syphilis which may result in blindness. Our data demonstrate outcomes for ocular syphilis are poor if detected late; early recognition and diagnosis is therefore vital to avoid permanent visual loss.

Melatonin mitigates cadmium and aluminium toxicity through modulation of antioxidant potential in Brassica napus L

Melatonin has emerged as an essential molecule in plants, due to its role in defence against metal toxicity. Aluminium (Al) and cadmium (Cd) toxicity inhibit rapeseed seedling growth. In this study, we applied different doses of melatonin (50 and 100 µm) to alleviate Al (25 µm) and Cd (25 µm) stress in rapeseed seedlings. Results show that Al and Cd caused toxicity in rapeseed seedling, as evidenced by a decrease in height, biomass and antioxidant enzyme activity. Melatonin increased the expression of melatonin biosynthesis-related Brassica napus genes for caffeic acid O-methyl transferase (BnCOMT) under Al and Cd stress. The genes BnCOMT-1, BnCOMT-5 and BnCOMT-8 showed up-regulated expression, while BnCOMT-4 and BnCOMT-6 were down-regulated during incubation in water. Melatonin application increased the germination rate, shoot length, root length, fresh and dry weight of seedlings. Melatonin supplementation under Al and Cd stress increased superoxide dismutase, catalase, peroxidase, ascorbate peroxidase, proline, chlorophyll and anthocyanin content, as well as photosynthesis rate. Both Cd and Al treatments significantly increased hydrogen peroxide and malondialdehyde levels in rapeseed seedlings, which were strictly counterbalanced by melatonin. Analysis of Cd and Al in different subcellular compartments showed that melatonin enhanced cell wall and soluble fractions, but reduced the vacuolar and organelle fractions in Al- and Cd-treated seedlings. These results suggest that melatonin-induced improvements in antioxidant potential, biomass, photosynthesis rate and successive Cd and Al sequestration play a pivotal role in plant tolerance to Al and Cd stress. This mechanism may have potential implications in safe food production.

Current-Induced Thermal Tunneling Electroluminescence in a Single Highly Compensated Semiconductor Microrod

Here we demonstrate a novel and robust mechanism, termed as “current-induced Joule heating activated thermal tunneling excitation,” to achieve electroluminescence (EL) by the hot electron-hole-pair recombination in a single highly compensated semiconductor microrod. The radiative luminescence is electrically excited under ambient conditions. The current-induced Joule heating reduces the thermal tunneling excitation threshold of voltage down to 8 V and increases the EL efficiency ~4.4-fold at 723 K. We interpret this novel phenomenon by a thermal tunneling excitation model corrected by electric-induced Joule heating effect. The mechanism is confirmed via theoretical calculation and experimental demonstration, for the first time. The color-tunable EL emission is also achieved by regulation of donor concentration. This work opens up new opportunities for design of novel multi-color light-emitting devices by homogeneous defect-engineered semiconductors in future.

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Current-induced thermal tunneling EL is found in a homogeneous HC-ZnO microrod

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The high temperature is beneficial to the current-induced thermal tunneling EL

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The tunneling mechanism of Joule-heating-facilitated excitation is revealed

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The color-tunable EL emission is demonstrated by regulation of donor concentration