Electrical Detection of Charge-to-spin and Spin-to-Charge Conversion in a Topological Insulator Bi2Te3 Using BN/Al2O3 Hybrid Tunnel Barrier

One of the most striking properties of three-dimensional topological insulators (TIs) is spin-momentum locking, where the spin is locked at right angles to momentum and hence an unpolarized charge current creates a net spin polarization. Alternatively, if a net spin is injected into the TI surface state system, it is distinctively associated with a unique carrier momentum and hence should generate a charge accumulation, as in the so-called inverse Edelstein effect. Here using a Fe/Al₂O₃/BN tunnel barrier, we demonstrate both effects in a single device in Bi₂Te₃: the electrical detection of the spin accumulation generated by an unpolarized current flowing through the surface states, and that of the charge accumulation generated by spins injected into the surface state system. This work is the first to utilize BN as part of a hybrid tunnel barrier on TI, where we observed a high spin polarization of 93% for the TI surfaces states. The reverse spin-to-charge measurement is an independent confirmation that spin and momentum are locked in the surface states of TI, and offers additional avenues for spin manipulation. It further demonstrates the robustness and versatility of electrical access to the spin system within TI surface states, an important step towards its utilization in TI-based spintronics devices.

Engineering the spin polarization of one-dimensional electrons

We present results of magneto-focusing on the controlled monitoring of spin polarization within a one-dimensional (1D) channel, and its subsequent effect on modulating the spin-orbit interaction (SOI) in a 2D GaAs electron gas. We demonstrate that electrons within a 1D channel can be partially spin polarized as the effective length of the 1D channel is varied in agreement with the theoretical prediction. Such polarized 1D electrons when injected into a 2D region result in a split in the odd-focusing peaks, whereas the even peaks remain unaffected (single peak). On the other hand, the unpolarized electrons do not affect the focusing spectrum and the odd and even peaks remain as single peaks, respectively. The split in odd-focusing peaks is evidence of direct measurement of spin polarization within a 1D channel, where each sub-peak represents the population of a particular spin state. Confirmation of the spin splitting is determined by a selective modulation of the focusing peaks due to the Zeeman energy in the presence of an in-plane magnetic field. We suggest that the SOI in the 2D regime is enhanced by a stream of polarized 1D electrons. The spatial control of spin states of injected 1D electrons and the possibility of tuning the SOI may open up a new regime of spin-engineering with application in future quantum information schemes.

Combined skin and muscle vaccination differentially impact the quality of effector T cell functions: the CUTHIVAC-001 randomized trial

Targeting of different tissues via transcutaneous (TC), intradermal (ID) and intramuscular (IM) injection has the potential to tailor the immune response to DNA vaccination. In this Phase I randomised controlled clinical trial in HIV-1 negative volunteers we investigate whether the site and mode of DNA vaccination influences the quality of the cellular immune responses. We adopted a strategy of concurrent immunization combining IM injection with either ID or TC administration. As a third arm we assessed the response to IM injection administered with electroporation (EP). The DNA plasmid encoded a MultiHIV B clade fusion protein designed to induce cellular immunity. The vaccine and regimens were well tolerated. We observed differential shaping of vaccine induced virus-specific CD4 + and CD8 + cell-mediated immune responses. DNA given by IM + EP promoted strong IFN-γ responses and potent viral inhibition. ID + IM without EP resulted in a similar pattern of response but of lower magnitude. By contrast TC + IM (without EP) shifted responses towards a more Th-17 dominated phenotype, associated with mucosal and epidermal protection. Whilst preliminary, these results offer new perspectives for differential shaping of desired cellular immunity required to fight the wide range of complex and diverse infectious diseases and cancers.

Atf3 deficiency promotes genome instability and spontaneous tumorigenesis in mice

Mice lacking genes involving in the DNA damage response (DDR) are often tumor prone owing to genome instability caused by oncogenic challenges. Previous studies demonstrate that activating transcription factor 3 (ATF3), a common stress sensor, can activate the tumor suppressor p53 and regulate expression of p53 target genes upon DNA damage. However, whether ATF3 contributes to the maintenance of genome stability and tumor suppression remains unknown. Here we report that Atf3-deficient (Atf3^-/-) mice developed spontaneous tumors, and died significantly earlier than wild-type (Atf3^+/+) mice. Consistent with these results, Atf3^-/- mouse embryonic fibroblasts (MEFs) had more aberrant chromosomes and micronuclei, and were genetically unstable. Whereas we demonstrated that ATF3 activated p53 and promoted its pro-apoptotic activity in mouse thymi and small intestines, the chromosomal instability caused by Atf3 deficiency was largely dependent on the regulation of p53 by ATF3. Interestingly, loss of Atf3 also promoted spontaneous tumorigenesis in Trp53^+/- mice, but did not affect tumor formation in Trp53^-/- mice. Our results thus provide the first genetic evidence linking ATF3 to the suppression of the early development of cancer, and underscore the importance of ATF3 in the maintenance of genome integrity.

[Clinical efficacy of acute intraoperative encephalocele prevention strategy for severe traumatic brain injury]

Objective: To explore the clinical efficacy of prevention strategy for acute intraoperative encephalocele of patients with severe traumatic brain injury (sTBI). Methods: A total of 173 patients with sTBI, who treated in Emergency Neurosurgery Department of Shandong University Qilu Hospital from January, 2011 to September, 2015 were collected and divided into research group and control group, according to their therapeutic strategy.The clinical data during hospitalization and prognosis 1 year after injury was analyzed retrospectively to clarify the effect of acute encephalocele prevention strategy. Results: There were no statistically significant differences in sex, age, preoperative Glasgow coma scale score and imaging type of lesion between patients from the two groups.The highest intraoperative intracranial pressure in the research group and control group were (35.71±4.13) mmHg and(34.85±3.81) mmHg, respectively.The acute encephalocele incidence of the research group (7 cases, 6.5%) was significantly lower than that of the control group (13 cases, 19.7%) (P<0.01). Subgroup analysis showed that the incidence of acute encephalocele in patients with only unilateral lesions was low (1.3%), while higher (19.4%) in patients with both unilateral lesions and other secondary lesions or diffuse brain swelling.The prognosis of the patients was evaluated by Glasgow Outcome Scale according to the follow-up 1 year after injury, and it was suggested that the percentage of patients with good outcome in the research group (62 cases, 57.9%) was remarkably higher than that in the control group (26 cases, 39.4%) (P=0.018). Conclusions: For sTBI patients with high risk of acute encephalocele, prevention strategy was found to be able to retard the progression of delayed hematoma and diffuse brain swelling, prevent the acute encephalocele during operation, and then significantly improve the prognosis.

Butyrate and retinoic acid imprint mucosal-like dendritic cell development synergistically from bone marrow cells

Accumulating data show that the phenotypes and functions of distinctive mucosal dendritic cells (DCs) in the gut are regulated by retinoic acid (RA). Unfortunately, the exact role of butyrate in RA-mediated mucosal DC differentiation has not been elucidated thoroughly to date. Mucosal-like dendritic cell differentiation was completed in vitro by culturing bone marrow cells with growth factors [granulocyte-macrophage colony-stimulating factor (GM-CSF/interleukin (IL)-4], RA and/or butyrate. The phenotypes, cytokine secretion, immune functions and levels of retinal dehydrogenase of different DCs were detected using quantitative polymerase chain reaction (qPCR), enzyme-linked immunosorbent assay (ELISA) and flow cytometry, respectively. The results showed that RA-induced DCs (RA-DCs) showed mucosal DC properties, including expression of CD103 and gut homing receptor α₄ β₇ , low proinflammatory cytokine secretion and low priming capability to antigen-specific CD4⁺ T cells. Butyrate-treated RA-DCs (Bu-RA-DCs) decreased CD11c, but increased CD103 and α₄ β₇ expression. Moreover, the CD4⁺ T priming capability and the levels of retinal dehydrogenase of RA-DCs were suppressed significantly by butyrate. Thus, butyrate and retinoic acid have different but synergistic regulatory functions on mucosal DC differentiation, indicating that immune homeostasis in the gut depends largely upon RA and butyrate to imprint different mucosal DC subsets, both individually and collectively.

Surfactant reduced the mortality of neonates with birth weight ⩾1500 g and hypoxemic respiratory failure: a survey from an emerging NICU network

OBJECTIVE

We evaluated the efficacy of surfactant therapy and assisted ventilation on morbidity and mortality of neonates with birth weight (BW) ⩾1500 g and hypoxemic respiratory failure (HRF).

STUDY DESIGN

We retrospectively analyzed 5650 patients with BW ⩾1500 g for incidence, management and outcome of HRF, defined as acute hypoxemia requiring mechanical ventilation and/or nasal continuous positive airway pressure ⩾24 h. The patients were allocated into groups of moderate preterm (1735, 30.7%), late preterm (1431, 25.4%), early term (ETM, 986, 17.5%), full term (1390, 24.6%) and post term (79, 1.4%), with gestational age ⩽33, 34 to 36, 37 to 38, 39 to 41 and ⩾42 weeks, respectively.

RESULTS

In the five groups, 66.9, 42, 21.6, 12.8 and 5.1% had respiratory distress syndrome (RDS). For pneumonia/sepsis and meconium aspiration syndrome (MAS), the proportion was 13.8%, 25.4%, 38.0%, 52.5% and 76.0%, respectively. Surfactant was given to 21.9% (n=1238) of HRF and 51.2% (n=1108) of RDS. Survival rates of RDS were 82.2%, 87.8%, 84.5%, 77.1% and 75.0%, respectively (numbers needed to treat was 8 to 11 for surfactant benefit). Overall mortality rate of HRF was 21%, or 17.9%, 14.7%, 25.6%, 28.9% and 39.2%, respectively. Mortalities of MAS and pneumonia/sepsis were 29.4 and 27.6%. Relative risk of death was associated with initial disease severity, female gender, mechanical ventilation and congenital anomalies by multivariate logistic regression analysis.

CONCLUSION

Surfactant was effective for infants with RDS and BW ⩾1500 g, and different incidences and outcome of HRF among GA groups reflected standard of perinatal and respiratory care in emerging neonatal intensive care unit network.

[Laparoscopic reoperation for recurred antireflux surgery of gastroesophageal reflux disease]

OBJECTIVE

To investigate the safety and effectiveness of laparoscopic reoperation for patients with gastroesophageal reflux disease (GERD) recurred form previous anti-reflux surgery.

METHODS

Totally 19 patients received laparoscopic reoperation for symptomatic and anatomic recurred GERD in Department of Gastroesophageal Reflux Disease, Rocket Force General Hospital from January 2008 to September 2015 were retrospectively analyzed. There were 12 male and 7 female patients. The average reoperation age was (48±14) years, the average duration of reoperation from original ones was (43±38) months. The patients underwent preoperative barium, endoscopy, manometry and 24-hour pH studies. Laparoscopic hiatal hernia repair plus fundoplication was carried out for reoperation. Gastroesophageal reflux related symptoms (reflux, heartburn, chest pain, chough, wheezing, chest tightness and globus sensation) before and after surgery were compared by a questionnaire. The patients' medication consumption, complications and satisfaction of the reoperation were investigated as well. The repeated measures analysis of variance was used for statistical comparison of data preoperatively and postoperatively.

RESULTS

No major complication and death occurred. Six cases (32%) had complications such as diarrhea, increased passing wind, flatulence, dysphagia and abdominal pain. The GERD related symptom score of reflux, heartburn, chest pain, chough, wheezing, chest tightness and globus sensation all significantly decreased (F: 25.0 to 56.7; P: 0.000 to 0.001) after the reoperation, with 68% good outcome of all the patients. After a follow-up of (33±22) months after reoperation, 1 case had partial recurrence at the 3(rd) month after reoperation. For all the patients, 12 cases felt very satisfied or satisfied with the reoperation.

CONCLUSION

Laparoscopic reoperation is generally effective with acceptable morbidity rates for patients with esophageal and extraesophageal symptoms recurred form previous hiatal repair and (or) fundoplication.

Increased glycogen synthase kinase-3β and hexose-6-phosphate dehydrogenase expression in adipose tissue may contribute to glucocorticoid-induced mouse visceral adiposity

BACKGROUND

Increased adiposity in visceral depots is a crucial feature associated with glucocorticoid (GC) excess. The action of GCs in target tissue is regulated by GC receptor (GR) and 11ß-hydroxysteroid dehydrogenase type 1 (11ß-HSD1) coupled with hexose-6-phosphate dehydrogenase (H6pdh). Glycogen synthase kinase-3β (GSK3β) is known to be a crucial mediator of ligand-dependent gene transcription. We hypothesized that the major effects of corticosteroids on adipose fat accumulation are in part medicated by changes in GSK3β and H6pdh.

METHODS

We characterized the alterations of GSK3β and GC metabolic enzymes, and determined the impact of GR antagonist mifepristone on obesity-related genes and the expression of H6pdh and 11ß-HSD1 in adipose tissue of mice exposed to excess GC as well as in in vitro studies using 3T3-L1 adipocytes treated with GCs.

RESULTS

Corticosterone (CORT) exposure increased abdominal fat mass and induced expression of lipid synthase ACC and ACL with activation of GSK3β phosphorylation in abdominal adipose tissue of C57BL/6J mice. Increased pSer⁹ GSK3β was correlated with induction of H6pdh and 11ß-HSD1. Additionally, mifepristone treatment reversed the production of H6pdh and attenuated CORT-mediated production of 11ß-HSD1 and lipogenic gene expression with reduction of pSer⁹ GSK3β, thereby leading to improvement of phenotype of adiposity within adipose tissue in mice treated with excess GCs. Suppression of pSer⁹ GSK3β by mifepristone was accompanied by activation of pThr³⁰⁸ Akt and blockade of CORT-induced adipogenic transcriptor C/EBPα and PPARγ. In addition, mifepristone also attenuated CORT-mediated activation of IRE1α/XBP1. Additionally, reduction of H6pdh by shRNA showed comparable effects to mifepristone on attenuating CORT-induced expression of GC metabolic enzymes and improved lipid accumulation in vitro in 3T3-L1 adipocytes.

CONCLUSION

These findings suggest that elevated adipose GSK3β and H6pdh expression contribute to 11ß-HSD1 mediating hypercortisolism associated with visceral adiposity.

Artesunate protects pancreatic beta cells against cytokine-induced damage via SIRT1 inhibiting NF-κB activation

AIM

Artesunate (ART) has been known as the most effective and safe reagents to treat malaria for many years. In this study, we explored whether ART could protect pancreatic beta-cell against cytokine-induced damage.

MATERIALS AND METHODS

The production of nitrite (NO) was detected with the Griess Assay Kit. SIRT1 and inducible nitric oxide synthase (iNOS) expression were determined with Western blot. The transcriptional activity of NF-κB was evaluated by luciferase reporter assay. The expression of Sirt1 was silenced by RNA interference. Glucose-stimulated insulin secretion (GSIS) and potassium-stimulated insulin secretion (KSIS) assays were performed to measure the effect of ART on pancreatic beta-cells' function. The effect of ART on beta-cells apoptosis was evaluated by using Hochest/PI staining and TUNEL assay.

RESULTS

ART enhanced GSIS (KSIS) and reduced apoptosis of pancreatic beta-cells induced by IL-1β. Further study showed that ART inhibited IL-1β-induced increase of NF-κB activity, iNOS expression, and NO production. Moreover, ART up-regulated SIRT1 expression in INS-1 cells and islets exposed to IL-1β. Inhibition of SIRT1 expression could partially abolished the inhibitory effect of ART on NF-κB activity in IL-1β-treated beta-cells. More importantly, the protective effect of ART on cytokine-induced damage was reversed by silencing SIRT1 expression.

CONCLUSIONS

ART can elicit a protective effect on beta-cells exposed to IL-1β by stimulating SIRT1 expression, which resulted in the decrease of NF-κB activity, iNOS expression, and NO production. Hence, ART might be an effective drug for diabetes.

Loss of ATF3 promotes hormone-induced prostate carcinogenesis and the emergence of CK5(+)CK8(+) epithelial cells

Steroid sex hormones can induce prostate carcinogenesis, and are thought to contribute to the development of prostate cancer during aging. However, the mechanism for hormone-induced prostate carcinogenesis remains elusive. Here we report that activating transcription factor 3 (ATF3) – a broad stress sensor – suppressed hormone-induced prostate carcinogenesis in mice. While implantation of testosterone and estradiol (T+E₂) pellets for 2 months in wild-type mice rarely induced prostatic intraepithelial neoplasia (PIN) in dorsal prostates (1 out of 8 mice), loss of ATF3 led to the appearance of not only PIN but also invasive lesions in almost all examined animals. The enhanced carcinogenic effects of hormones on ATF3-deficient prostates did not appear to be caused by a change in estrogen signaling, but were more likely a consequence of elevated androgen signaling that stimulated differentiation of prostatic basal cells into transformation-preferable luminal cells. Indeed, we found that hormone-induced lesions in ATF3-knockout mice often contained cells with both basal and luminal characteristics, such as p63⁺ cells (a basal cell marker) showing luminal-like morphology, or cells double-stained with basal (CK5⁺) and luminal (CK8⁺) markers. Consistent with these findings, low ATF3 expression was found to be a poor prognostic marker for prostate cancer in a cohort of 245 patients. Our results thus support that ATF3 is a tumor suppressor in prostate cancer.

RNF126 promotes homologous recombination via regulation of E2F1-mediated BRCA1 expression

RNF126 is an E3 ubiquitin ligase. The deletion of RNF126 gene was observed in a wide range of human cancers and is correlated with improved disease-free and overall survival. These data highlights the clinical relevance of RNF126 in tumorigenesis and cancer therapy. However, the specific functions of RNF126 remain largely unknown. Homologous recombination (HR)-mediated DNA double-strand break repair is important for tumor suppression and cancer therapy resistance. Here, we demonstrate that RNF126 facilitates HR by promoting the expression of BRCA1, in a manner independent of its E3 ligase activity but depending on E2F1, a well-known transcription factor of BRCA1 promoter. In support of this result, RNF126 promotes transactivation of BRCA1 promoter by directly binding to E2F1. Most importantly, an RNF126 mutant lacking 11 amino acids that is responsible for the interaction with E2F1 has a dominant-negative effect on BRCA1 expression and HR by suppressing E2F1-mediated transactivation of BRCA1 promoter and blocking the enrichment of E2F1 on BRCA1 promoter. Lastly, RNF126 depletion leads to the increased sensitivity to ionizing radiation (IR) and poly (ADP-ribose) polymerase (PARP) inhibition. Collectively, our results suggest a novel role of RNF126 in promoting HR-mediated repair through positive regulation on BRCA1 expression by direct interaction with E2F1. This study not only offers novel insights into our current understanding of the biological functions of RNF126 but also provides a potential therapeutic target for cancer treatment.