Working Toward a Gold Standard: The Severity of Ethanol Withdrawal Scale (SEWS) Versus the Clinical Institute Withdrawal Assessment Alcohol Scale (CIWA-Ar)

AIM

Proving the Severity of Ethanol Withdrawal Scale (SEWS) significantly reduces Alcohol Withdrawal Syndrome (AWS) treatment Time on Medication Protocol (TOMP).

METHOD

Head-to-head Quality Assurance outcome compared separate cohorts of SEWS or Clinical Institute Withdrawal Assessment Alcohol Scale, Revised (CIWA-Ar) data using Student's t and Wilcoxon tests.

RESULTS

SEWS-driven treatment (n = 244) reduced TOMP to 2.2 days versus 3.4 days for CIWA-Ar (n = 137); P < 0.0001.

CONCLUSION

The SEWS is the superior measure of AWS symptoms.

Transfusion trigger after operations in high cardiac risk patients (TOP) trial protocol. Protocol for a multicenter randomized controlled transfusion strategy trial

BACKGROUND

There is substantial uncertainty regarding the effects of restrictive postoperative transfusion among patients who have underlying cardiovascular disease. The TOP Trial's objective is to compare adverse outcomes between liberal and restrictive transfusion strategies in patients undergoing vascular and general surgery operations, and with a high risk of postoperative cardiac events.

METHODS

A two-arm, single-blinded, randomized controlled superiority trial will be used across 15 Veterans Affairs hospitals with expected enrollment of 1520 participants. Postoperative transfusions in the liberal arm commence when Hb is <10 g/ dL and continue until Hb is greater than or equal to 10 g/dL. In the restrictive arm, transfusions begin when Hb is <7 g/dL and continue until Hb is greater than or equal to 7 g/dL. Study duration is estimated to be 5 years including a 3-month start-up period and 4 years of recruitment. Each randomized participant will be followed for 90 days after randomization with a mortality assessment at 1 year.

RESULTS

The primary outcome is a composite endpoint of all-cause mortality, myocardial infarction (MI), coronary revascularization, acute renal failure, or stroke occurring up to 90-days after randomization. Events rates will be compared between restrictive and liberal transfusion groups.

CONCLUSIONS

The TOP Trial is uniquely positioned to provide high quality evidence comparing transfusion strategies among patients with high cardiac risk. Results will clarify the effect of postoperative transfusion strategies on adverse outcomes and inform postoperative management algorithms.

TRIAL REGISTRATION

http://clinicaltrials.gov identifier: NCT03229941.

Effect of Androgen Suppression on Clinical Outcomes in Hospitalized Men With COVID-19: The HITCH Randomized Clinical Trial

IMPORTANCE

SARS-CoV-2 entry requires the TMPRSS2 cell surface protease. Antiandrogen therapies reduce expression of TMPRSS2.

OBJECTIVE

To determine if temporary androgen suppression induced by degarelix improves clinical outcomes of inpatients hospitalized with COVID-19.

DESIGN, SETTING, AND PARTICIPANTS

The Hormonal Intervention for the Treatment in Veterans With COVID-19 Requiring Hospitalization (HITCH) phase 2, placebo-controlled, double-blind, randomized clinical trial compared efficacy of degarelix plus standard care vs placebo plus standard care on clinical outcomes in men hospitalized with COVID-19 but not requiring invasive mechanical ventilation. Inpatients were enrolled at 14 Department of Veterans Affairs hospitals from July 22, 2020, to April 8, 2021. Data were analyzed from August 9 to October 15, 2021.

INTERVENTIONS

Patients stratified by age, history of hypertension, and disease severity were centrally randomized 2:1 to degarelix, (1-time subcutaneous dose of 240 mg) or a saline placebo. Standard care included but was not limited to supplemental oxygen, antibiotics, vasopressor support, peritoneal dialysis or hemodialysis, intravenous fluids, remdesivir, convalescent plasma, and dexamethasone.

MAIN OUTCOMES AND MEASURES

The composite primary end point was mortality, ongoing need for hospitalization, or requirement for mechanical ventilation at day 15 after randomization. Secondary end points were time to clinical improvement, inpatient mortality, length of hospitalization, duration of mechanical ventilation, time to achieve a temperature within reference range, maximum severity of COVID-19, and the composite end point at 30 days.

RESULTS

The trial was stopped for futility after the planned interim analysis, at which time there were 96 evaluable patients, including 62 patients randomized to the degarelix group and 34 patients in the placebo group, out of 198 initially planned. The median (range) age was 70.5 (48-85) years. Common comorbidities included chronic obstructive pulmonary disorder (15 patients [15.6%]), hypertension (75 patients [78.1%]), cardiovascular disease (27 patients [28.1%]), asthma (12 patients [12.5%]), diabetes (49 patients [51.0%]), and chronic respiratory failure requiring supplemental oxygen at baseline prior to COVID-19 (9 patients [9.4%]). For the primary end point, there was no significant difference between the degarelix and placebo groups (19 patients [30.6%] vs 9 patients [26.5%]; P = .67). Similarly, no differences were observed between degarelix and placebo groups in any secondary end points, including inpatient mortality (11 patients [17.7%] vs 6 patients [17.6%]) or all-cause mortality (11 patients [17.7%] vs 7 patents [20.6%]). There were no differences between degarelix and placebo groups in the overall rates of adverse events (13 patients [21.0%] vs 8 patients [23.5%) and serious adverse events (19 patients [30.6%] vs 13 patients [32.4%]), nor unexpected safety concerns.

CONCLUSIONS AND RELEVANCE

In this randomized clinical trial of androgen suppression vs placebo and usual care for men hospitalized with COVID-19, degarelix did not result in amelioration of COVID-19 severity.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04397718.

Hormonal intervention for the treatment of veterans with COVID-19 requiring hospitalization (HITCH): a multicenter, phase 2 randomized controlled trial of best supportive care vs best supportive care plus degarelix: study protocol for a randomized controlled trial

Background

Therapeutic targeting of host-cell factors required for SARS-CoV-2 entry is an alternative strategy to ameliorate COVID-19 severity. SARS-CoV-2 entry into lung epithelium requires the TMPRSS2 cell surface protease. Pre-clinical and correlative data in humans suggest that anti-androgenic therapies can reduce the expression of TMPRSS2 on lung epithelium. Accordingly, we hypothesize that therapeutic targeting of androgen receptor signaling via degarelix, a luteinizing hormone-releasing hormone (LHRH) antagonist, will suppress COVID-19 infection and ameliorate symptom severity.

Methods

This is a randomized phase 2, placebo-controlled, double-blind clinical trial in 198 patients to compare efficacy of degarelix plus best supportive care versus placebo plus best supportive care on improving the clinical outcomes of male Veterans who have been hospitalized due to COVID-19. Enrolled patients must have documented infection with SARS-CoV-2 based on a positive reverse transcriptase polymerase chain reaction result performed on a nasopharyngeal swab and have a severity of illness of level 3–5 (hospitalized but not requiring invasive mechanical ventilation). Patients stratified by age, history of hypertension, and severity are centrally randomized 2:1 (degarelix: placebo). The composite primary endpoint is mortality, ongoing need for hospitalization, or requirement for mechanical ventilation at 15 after randomization. Important secondary endpoints include time to clinical improvement, inpatient mortality, length of hospitalization, duration of mechanical ventilation, time to achieve a normal temperature, and the maximum severity of COVID-19 illness. Exploratory analyses aim to assess the association of cytokines, viral load, and various comorbidities with outcome. In addition, TMPRSS2 expression in target tissue and development of anti-viral antibodies will also be investigated.

Discussion

In this trial, we repurpose the FDA approved LHRH antagonist degarelix, commonly used for prostate cancer, to suppress TMPRSS2, a host cell surface protease required for SARS-CoV-2 cell entry. The objective is to determine if temporary androgen suppression with a single dose of degarelix improves the clinical outcomes of patients hospitalized due to COVID-19.

Trial registration

ClinicalTrials.gov NCT04397718. Registered on May 21, 2020

Engineering CRISPR interference system to enhance the production of pyrroloquinoline quinone in Klebsiella pneumonia

Pyrroloquinoline quinone (PQQ) is a cofactor of glucose dehydrogenase (GDH) and thus participates in glucose utilization. In Klebsiella pneumoniae, glucose utilization involves PQQ-dependent direct oxidation pathway (DOP) and phosphoenolpyruvate-dependent transport system (PTS). It is challenging to overproduce PQQ, as its biosynthesis remains unclear. Here, we report that PQQ production can be enhanced by stimulating the metabolic demand for it. First, we developed CRISPR interference (CRISPRi) system to block PTS and thereby intensify DOP. In shake-flask cultivation, the strain with CRISPRi system (simultaneously inhibiting four PTS-related genes) produced 225·65 nmol l^-1 PQQ, which was 2·14 times that of wild type. In parallel, an exogenous soluble glucose dehydrogenase (sGDH) was overexpressed in K. pneumoniae. In the shake-flask cultivation, this sGDH-overexpressing strain accumulated 140·05 nmol l^-1 PQQ, which was 1·33 times that of wild type. To combine the above two strategies, we engineered a strain harbouring both CRISPRi vector and sGDH-overexpressing vector. In the shake-flask cultivation, this two-plasmid strain generated 287·01 nmol l^-1 PQQ, which was 2·72 times that of wild type. In bioreactor cultivation, this two-plasmid strain produced 2206·1 nmol l^-1 PQQ in 57 h, which was 7·69 times that in shake-flask cultivation. These results indicate that PQQ production can be enhanced by intensifying DOP, as the apo-enzyme GDH is intrinsically coupled with cofactor PQQ. This study provides a strategy for the production of cofactors whose biosynthesis mechanisms remain ambiguous. SIGNIFICANCE AND IMPACT OF THE STUDY: Pyrroloquinoline quinone (PQQ) is an economically important chemical, which typically serves as a cofactor of glucose dehydrogenase (GDH) and thus participates in glucose metabolism. Klebsiella pneumoniae can naturally synthesize PQQ, but current yield constrains its commercialization. In this study, the PQQ level was improved by stimulating metabolic demand for PQQ, instead of overexpressing PQQ synthetic genes, as the synthetic mechanism remains ambiguous.

Effect of electron blocking layer on the efficiency of AlGaN mid-ultraviolet light emitting diodes

The performance of AlGaN-based mid and deep ultraviolet light emitting diodes (LEDs) is severely limited by electron overflow and by the poor hole injection into the device active region. We have studied the effect of various electron blocking layers on the performance of AlGaN LEDs operating at ~280 nm. It is observed that, compared to conventional p-type electron blocking layer, the incorporation of an n-type AlN/AlGaN superlattice electron blocking layer before the active region can significantly improve the device performance by reducing electron overflow without compromising hole injection. Direct on-wafer measurement showed an external quantum efficiency ~4.4% and wall-plug efficiency ~2.8% by optimizing the design of n-type AlN/AlGaN superlattice electron blocking layer, which is nearly a factor of five to ten times better than identical devices but with the incorporation of a conventional p-type electron blocking layer.

Structural and electrical characterization of monolithic core-double shell n-GaN/Al/p-AlGaN nanowire heterostructures grown by molecular beam epitaxy

We have studied the epitaxy and structural characterization of monolithic n-GaN/Al/p-AlGaN nanowire heterostructures. It is found that high quality, nearly defect free, full shell epitaxial Al can be grown in situ on Al(Ga)N nanowires and vice versa. Detailed scanning transmission electron microscopy (STEM), high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) suggest that the Al (111) plane maintains an epitaxial relationship with Al(Ga)N (0001) in the nanowire growth direction. Full ultraviolet composition range (340 nm-210 nm) Al/Al(Ga)N core-double shell nanowire backward diode characteristics were investigated. We have demonstrated a monolithic n⁺⁺-GaN/Al/p⁺⁺-Al(Ga)N nanowire backward diode, wherein an epitaxial Al layer serves as the tunnel junction. Such an Al(Ga)N-based n-p-n nanowire backward diode exhibits record low resistivity (<1.5 × 10^-4Ω cm²) and a low turn-on voltage of ∼2.7 V.

An electrically injected AlGaN nanowire defect-free photonic crystal ultraviolet laser

We report on the demonstration of an electrically injected AlGaN nanowire photonic crystal laser that can operate in the ultraviolet spectral range. The nanowire heterostructures were grown on sapphire substrate using a site-controlled selective area growth process. By exploiting the topological high-Q resonance of a defect-free nanowire photonic crystal, we have demonstrated electrically pumped lasers that can operate at 369.5 nm with a relatively low threshold current density of ~2.1 kA/cm² under continuous wave operation at room-temperature. This work provides a promising approach for achieving low threshold semiconductor laser diodes operating in the UV spectral range that were previously difficult.

Complementary cathodoluminescence lifetime imaging configurations in a scanning electron microscope

Cathodoluminescence (CL) spectroscopy provides a powerful way to characterize optical properties of materials with deep-subwavelength spatial resolution. While CL imaging to obtain optical spectra is a well-developed technology, imaging CL lifetimes with nanoscale resolution has only been explored in a few studies. In this paper we compare three different time-resolved CL techniques and compare their characteristics. Two configurations are based on the acquisition of CL decay traces using a pulsed electron beam that is generated either with an ultra-fast beam blanker, which is placed in the electron column, or by photoemission from a laser-driven electron cathode. The third configuration uses measurements of the autocorrelation function g⁽²⁾ of the CL signal using either a continuous or a pulsed electron beam. The three techniques are compared in terms of complexity of implementation, spatial and temporal resolution, and measurement accuracy as a function of electron dose. A single sample of InGaN/GaN quantum wells is investigated to enable a direct comparison of lifetime measurement characteristics of the three techniques. The g⁽²⁾-based method provides decay measurements at the best spatial resolution, as it leaves the electron column configuration unaffected. The pulsed-beam methods provide better detail on the temporal excitation and decay dynamics. The ultra-fast blanker configuration delivers electron pulses as short as 30 ps at 5 keV and 250 ps at 30 keV. The repetition rate can be chosen arbitrarily up to 80 MHz and requires a conjugate plane geometry in the electron column that reduces the spatial resolution in our microscope. The photoemission configuration, pumped with 250 fs 257 nm pulses at a repetition rate from 10 kHz to 25 MHz, allows creation of electron pulses down to a few ps, with some loss in spatial resolution.

Effect of Repetitive Transcranial Magnetic Stimulation on Treatment-Resistant Major Depression in US Veterans: A Randomized Clinical Trial

IMPORTANCE

Treatment-resistant major depression (TRMD) in veterans is a major clinical challenge given the high risk for suicidality in these patients. Repetitive transcranial magnetic stimulation (rTMS) offers the potential for a novel treatment modality for these veterans.

OBJECTIVE

To determine the efficacy of rTMS in the treatment of TRMD in veterans.

DESIGN, SETTING, AND PARTICIPANTS

A double-blind, sham-controlled randomized clinical trial was conducted from September 1, 2012, to December 31, 2016, in 9 Veterans Affairs medical centers. A total of 164 veterans with TRD participated.

INTERVENTIONS

Participants were randomized to either left prefrontal rTMS treatment (10 Hz, 120% motor threshold, 4000 pulses/session) or to sham (control) rTMS treatment for up to 30 treatment sessions.

MAIN OUTCOMES AND MEASURES

The primary dependent measure of the intention-to-treat analysis was remission rate (Hamilton Rating Scale for Depression score ≤10, indicating that depression is in remission and not a clinically significant burden), and secondary analyses were conducted on other indices of posttraumatic stress disorder, depression, hopelessness, suicidality, and quality of life.

RESULTS

The 164 participants had a mean (SD) age of 55.2 (12.4) years, 132 (80.5%) were men, and 126 (76.8%) were of white race. Of these, 81 were randomized to receive active rTMS and 83 to receive sham. For the primary analysis of remission, there was no significant effect of treatment (odds ratio, 1.16; 95% CI, 0.59-2.26; P = .67). At the end of the acute treatment phase, 33 of 81 (40.7%) of those in the active treatment group achieved remission of depressive symptoms compared with 31 of 83 (37.4%) of those in the sham treatment group. Overall, 64 of 164 (39.0%) of the participants achieved remission.

CONCLUSIONS AND RELEVANCE

A total of 39.0% of the veterans who participated in this trial experienced clinically significant improvement resulting in remission of depressive symptoms; however, there was no evidence of difference in remission rates between the active and sham treatments. These findings may reflect the importance of close clinical surveillance, rigorous monitoring of concomitant medication, and regular interaction with clinic staff in bringing about significant improvement in this treatment-resistant population.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01191333.

Discovery of 4 exonic and 1 intergenic novel susceptibility loci for leprosy

Seven new risk coding variants have been identified through an exome-wide association study (EWAS), which studied the contributions of protein-coding variants to leprosy susceptibility. But some potential susceptibility loci were not studied in the previous EWAS study because of the project consideration. Seventeen unstudied potential susceptibility loci of the previous EWAS were validated in 3169 cases and 9814 controls in this study. Four disease-associated exonic loci were identified: rs671 in ALDH2 (P = 2.0 × 10^-20 , odds ratio [OR] = 1.35), rs13259978 in SLC7A2 (P = 1.74 × 10^-8 , OR = 1.28), rs925368 in GIT2 (P = 9.18 × 10^-17 , OR = 1.44), and rs75680863 in TCN2 (P = 8.37 × 10^-21 , OR = 0.74). Potentially implicating ZFP36L1 as a new susceptibility gene, 1 intergenic single nucleotide polymorphism (SNP), rs1465788 (P = 7.81 × 10^-6 , OR = 0.88), was also suggested to be associated with leprosy. A luciferase reporter assay showed that the rs1465788 risk allele notably decreased the transcription activity of the flanking sequence. These findings suggest the possible involvement of lipid metabolism, NF-κB homeostasis and macrophage antimicrobial pathways in leprosy pathogenesis.

Repetitive transcranial magnetic stimulation (rTMS) for treatment-resistant major depression (TRMD) Veteran patients: study protocol for a randomized controlled trial

Background

Evaluation of repetitive transcranial magnetic stimulation (rTMS) for treatment-resistant major depression (TRMD) in Veterans offers unique clinical trial challenges. Here we describe a randomized, double-blinded, intent-to-treat, two-arm, superiority parallel design, a multicenter study funded by the Cooperative Studies Program (CSP No. 556) of the US Department of Veterans Affairs.

Methods

We recruited medical providers with clinical expertise in treating TRMD at nine Veterans Affairs (VA) medical centers as the trial local investigators. We plan to enroll 360 Veterans diagnosed with TRMD at the nine VA medical centers over a 3-year period. We will randomize participants into a double-blinded clinical trial to left prefrontal rTMS treatment or to sham (control) rTMS treatment (180 participants each group) for up to 30 treatment sessions. All participants will meet Diagnostic and statistical manual of mental disorders, 4^thedition (DSM-IV) criteria for major depression and will have failed at least two prior pharmacological interventions. In contrast with other rTMS clinical trials, we will not exclude Veterans with posttraumatic stress disorder (PTSD) or history of substance abuse and we will obtain detailed history regarding these disorders. Furthermore, we will maintain participants on stable anti-depressant medication throughout the trial. We will evaluate all participants on a wide variety of potential predictors of treatment response including cognitive, psychological and functional parameters.

Discussion

The primary dependent measure will be remission rate (Hamilton Rating Scale for Depression (HRSD24) ≤ 10), and secondary analyses will be conducted on other indices. Comparisons between the rTMS and the sham groups will be made at the end of the acute treatment phase to test the primary hypothesis. The unique challenges to performing such a large technically challenging clinical trial with Veterans and potential avenues for improvement of the design in future trials will be described.

Trial registration

ClinicalTrials.gov, NCT01191333. Registered on 26 August 2010. This report is based on the protocol version 4.6 amended in February 2016. All items from the World Health Organization Trial Registration Data Set are listed in Appendix A.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-2125-y) contains supplementary material, which is available to authorized users.

An AlGaN Core-Shell Tunnel Junction Nanowire Light-Emitting Diode Operating in the Ultraviolet-C Band

To date, semiconductor light emitting diodes (LEDs) operating in the deep ultraviolet (UV) spectral range exhibit very low efficiency due to the presence of large densities of defects and extremely inefficient p-type conduction of conventional AlGaN quantum well heterostructures. We have demonstrated that such critical issues can be potentially addressed by using nearly defect-free AlGaN tunnel junction core-shell nanowire heterostructures. The core-shell nanowire arrays exhibit high photoluminescence efficiency (∼80%) in the UV-C band at room temperature. With the incorporation of an epitaxial Al tunnel junction, the p-(Al)GaN contact-free nanowire deep UV LEDs showed nearly one order of magnitude reduction in the device resistance, compared to the conventional nanowire p-i-n device. The unpackaged Al tunnel junction deep UV LEDs exhibit an output power >8 mW and a peak external quantum efficiency ∼0.4%, which are nearly one to two orders of magnitude higher than previously reported AlGaN nanowire devices. Detailed studies further suggest that the maximum achievable efficiency is limited by electron overflow and poor light extraction efficiency due to the TM polarized emission.

Thyroid hormone therapy and procurement of livers from brain-dead donors

Hormonal therapy to brain-dead potential organ donors remains controversial. A retrospective study was carried out of hormonal therapy on procurement of organs in 63,593 donors in whom information on T3/T4 therapy was available. In 40,124 donors, T3/T4 and all other hormonal therapy was recorded. The percentages of all organs procured, except livers, were greater in T3/T4-treated donors. Nevertheless, if T3/T4 therapy had been administered to the donor, liver transplantation was associated with significantly increased graft and recipient survival at 1 month and 12 months. The potential reasons for the lack of effect of T3/T4 therapy on the number of livers procured are discussed.

Monolithically Integrated Metal/Semiconductor Tunnel Junction Nanowire Light-Emitting Diodes

We have demonstrated for the first time an n(++)-GaN/Al/p(++)-GaN backward diode, wherein an epitaxial Al layer serves as the tunnel junction. The resulting p-contact free InGaN/GaN nanowire light-emitting diodes (LEDs) exhibited a low turn-on voltage (∼2.9 V), reduced resistance, and enhanced power, compared to nanowire LEDs without the use of Al tunnel junction or with the incorporation of an n(++)-GaN/p(++)-GaN tunnel junction. This unique Al tunnel junction overcomes some of the critical issues related to conventional GaN-based tunnel junction designs, including stress relaxation, wide depletion region, and light absorption, and holds tremendous promise for realizing low-resistivity, high-brightness III-nitride nanowire LEDs in the visible and deep ultraviolet spectral range. Moreover, the demonstration of monolithic integration of metal and semiconductor nanowire heterojunctions provides a seamless platform for realizing a broad range of multifunctional nanoscale electronic and photonic devices.

Three-Dimensional Quantum Confinement of Charge Carriers in Self-Organized AlGaN Nanowires: A Viable Route to Electrically Injected Deep Ultraviolet Lasers

We report on the molecular beam epitaxial growth and structural characterization of self-organized AlGaN nanowire arrays on Si substrate with high luminescence efficiency emission in the deep ultraviolet (UV) wavelength range. It is found that, with increasing Al concentration, atomic-scale compositional modulations can be realized, leading to three-dimensional quantum confinement of charge carriers. By further exploiting the Anderson localization of light, we have demonstrated, for the first time, electrically injected AlGaN lasers in the deep UV band operating at room temperature. The laser operates at ∼289 nm and exhibits a threshold of 300 A/cm(2), which is significantly smaller compared to the previously reported electrically injected AlGaN multiple quantum well lasers.

A Metal-Nitride Nanowire Dual-Photoelectrode Device for Unassisted Solar-to-Hydrogen Conversion under Parallel Illumination

A dual-photoelectrode device, consisting of a photoanode and photocathode with complementary energy bandgaps, has long been perceived as an ideal scheme for achieving high efficiency, unassisted solar-driven water splitting. Previously reported 2-photon tandem devices, however, generally exhibit an extremely low efficiency (<0.1%), which has been largely limited by the incompatibility between the two photoelectrode materials. Here we show that the use of metal-nitride nanowire photoelectrodes, together with the scheme of parallel illumination by splitting the solar spectrum spatially and spectrally, can break the efficiency bottleneck of conventional 2-photon tandem devices. We have first investigated a dual-photoelectrode device consisting of a GaN nanowire photoanode and an InGaN nanowire photocathode, which exhibited an open circuit potential of 1.3 V and nearly 20-fold enhancement in the power conversion efficiency under visible light illumination (400-600 nm), compared to the individual photoelectrodes in 1 mol/L HBr. We have further demonstrated a dual-photoelectrode device consisting of parallel-connected metal-nitride nanowire photoanodes and a Si/InGaN nanowire photocathode, which can perform unassisted, direct solar-to-hydrogen conversion. A power conversion efficiency of 2% was measured under AM1.5G 1 sun illumination.

Alternating-Current InGaN/GaN Tunnel Junction Nanowire White-Light Emitting Diodes

The current LED lighting technology relies on the use of a driver to convert alternating current (AC) to low-voltage direct current (DC) power, a resistive p-GaN contact layer to inject positive charge carriers (holes) for blue light emission, and rare-earth doped phosphors to down-convert blue photons into green/red light, which have been identified as some of the major factors limiting the device efficiency, light quality, and cost. Here, we show that multiple-active region phosphor-free InGaN nanowire white LEDs connected through a polarization engineered tunnel junction can fundamentally address the afore-described challenges. Such a p-GaN contact-free LED offers the benefit of carrier regeneration, leading to enhanced light intensity and reduced efficiency droop. Moreover, through the monolithic integration of p-GaN up and p-GaN down nanowire LED structures on the same substrate, we have demonstrated, for the first time, AC operated LEDs on a Si platform, which can operate efficiently in both polarities (positive and negative) of applied voltage.

Surface Emitting, High Efficiency Near-Vacuum Ultraviolet Light Source with Aluminum Nitride Nanowires Monolithically Grown on Silicon

To date, it has remained challenging to realize electrically injected light sources in the vacuum ultraviolet wavelength range (∼200 nm or shorter), which are important for a broad range of applications, including sensing, surface treatment, and photochemical analysis. In this Letter, we have demonstrated such a light source with molecular beam epitaxially grown aluminum nitride (AlN) nanowires on low cost, large area Si substrate. Detailed angle dependent electroluminescence studies suggest that, albeit the light is TM polarized, the dominant light emission direction is from the nanowire top surface, that is, along the c axis, due to the strong light scattering effect. Such an efficient surface emitting device was not previously possible using conventional c-plane AlN planar structures. The AlN nanowire LEDs exhibit an extremely large electrical efficiency (>85%), which is nearly ten times higher than the previously reported AlN planar devices. Our detailed studies further suggest that the performance of AlN nanowire LEDs is predominantly limited by electron overflow. This study provides important insight on the fundamental emission characteristics of AlN nanowire LEDs and also offers a viable path to realize an efficient surface emitting near-vacuum ultraviolet light source through direct electrical injection.

Dye-sensitized InGaN nanowire arrays for efficient hydrogen production under visible light irradiation

Solar water splitting is a key sustainable energy technology for clean, storable and renewable source of energy in the future. Here we report that Merocyanine-540 dye-sensitized and Rh nanoparticle-decorated molecular beam epitaxially grown In0.25Ga0.75N nanowire arrays have produced hydrogen from ethylenediaminetetraacetic acid (EDTA) and acetonitrile mixture solution under green, yellow and orange solar spectra (up to 610 nm) for the first time. An apparent quantum efficiency of 0.3% is demonstrated for wavelengths 525-600 nm, providing a viable approach to harness deep-visible and near-infrared solar energy for efficient and stable water splitting.

Increased Procurement of Thoracic Donor Organs After Thyroid Hormone Therapy

Hormonal therapy to the brain-dead organ donor can include thyroid hormone (triiodothyronine [T3] or levothyroxine [T4]), antidiuretic hormone, corticosteroids, or insulin. There has been a controversy on whether thyroid hormone enables more organs to be procured. Data on 63,593 donors of hearts and lungs (2000-2009) were retrospectively reviewed. Documentation on T3/T4 was available in all donors (study 1), and in 40,124 details of all 4 hormones were recorded (study 2). In this cohort, group A (23,022) received T3/T4 and group B (17,102) no T3/T4. Univariate analyses and multiple regressions were performed. Posttransplant graft and recipient survival at 1 and 12 months were compared. In study 1, 30,962 donors received T3/T4, with 36.59% providing a heart and 20.05% providing 1 or both lungs. Of the 32,631 donors who did not receive T3/T4, only 29.62% provided a heart and 14.61% provided lungs, an increase of 6.97% hearts and 5.44% lungs from T3/T4-treated donors (both P < 0.0001). In study 2, 34.99% of group A provided a heart and 20.99% provided lungs. In group B only 25.76% provided a heart and 15.09% provided lungs, an increase of 9.23% (hearts) and 5.90% (lungs), respectively, in group A (both P < 0.0001). The results of multiple regression analyses indicated a beneficial effect of T3/T4 on heart (P < 0.0001) and lung (P < 0.0001) procurement independent of other factors. T3/T4 therapy to the donor was associated with either improved posttransplant graft and recipient survival or no difference in survival. T3/T4 therapy results in more transplantable hearts and lungs, with no detriment to posttransplant graft or recipient survival.

Osteopontin neutralisation abrogates the liver progenitor cell response and fibrogenesis in mice

BACKGROUND

Chronic liver injury triggers a progenitor cell repair response, and liver fibrosis occurs when repair becomes deregulated. Previously, we reported that reactivation of the hedgehog pathway promotes fibrogenic liver repair. Osteopontin (OPN) is a hedgehog-target, and a cytokine that is highly upregulated in fibrotic tissues, and regulates stem-cell fate. Thus, we hypothesised that OPN may modulate liver progenitor cell response, and thereby, modulate fibrotic outcomes. We further evaluated the impact of OPN-neutralisation on murine liver fibrosis.

METHODS

Liver progenitors (603B and bipotential mouse oval liver) were treated with OPN-neutralising aptamers in the presence or absence of transforming growth factor (TGF)-β, to determine if (and how) OPN modulates liver progenitor function. Effects of OPN-neutralisation (using OPN-aptamers or OPN-neutralising antibodies) on liver progenitor cell response and fibrogenesis were assessed in three models of liver fibrosis (carbon tetrachloride, methionine-choline deficient diet, 3,5,-diethoxycarbonyl-1,4-dihydrocollidine diet) by quantitative real time (qRT) PCR, Sirius-Red staining, hydroxyproline assay, and semiquantitative double-immunohistochemistry. Finally, OPN expression and liver progenitor response were corroborated in liver tissues obtained from patients with chronic liver disease.

RESULTS

OPN is overexpressed by liver progenitors in humans and mice. In cultured progenitors, OPN enhances viability and wound healing by modulating TGF-β signalling. In vivo, OPN-neutralisation attenuates the liver progenitor cell response, reverses epithelial-mesenchymal-transition in Sox9+ cells, and abrogates liver fibrogenesis.

CONCLUSIONS

OPN upregulation during liver injury is a conserved repair response, and influences liver progenitor cell function. OPN-neutralisation abrogates the liver progenitor cell response and fibrogenesis in mouse models of liver fibrosis.

Aluminum nitride nanowire light emitting diodes: Breaking the fundamental bottleneck of deep ultraviolet light sources

Despite broad interest in aluminum gallium nitride (AlGaN) optoelectronic devices for deep ultraviolet (DUV) applications, the performance of conventional Al(Ga)N planar devices drastically decays when approaching the AlN end, including low internal quantum efficiencies (IQEs) and high device operation voltages. Here we show that these challenges can be addressed by utilizing nitrogen (N) polar Al(Ga)N nanowires grown directly on Si substrate. By carefully tuning the synthesis conditions, a record IQE of 80% can be realized with N-polar AlN nanowires, which is nearly ten times higher compared to high quality planar AlN. The first 210 nm emitting AlN nanowire light emitting diodes (LEDs) were achieved, with a turn on voltage of about 6 V, which is significantly lower than the commonly observed 20 – 40 V. This can be ascribed to both efficient Mg doping by controlling the nanowire growth rate and N-polarity induced internal electrical field that favors hole injection. In the end, high performance N-polar AlGaN nanowire LEDs with emission wavelengths covering the UV-B/C bands were also demonstrated.

Ultralow-threshold electrically injected AlGaN nanowire ultraviolet lasers on Si operating at low temperature

Ultraviolet laser radiation has been adopted in a wide range of applications as diverse as water purification, flexible displays, data storage, sterilization, diagnosis and bioagent detection. Success in developing semiconductor-based, compact ultraviolet laser sources, however, has been extremely limited. Here, we report that defect-free disordered AlGaN core-shell nanowire arrays, formed directly on a Si substrate, can be used to achieve highly stable, electrically pumped lasers across the entire ultraviolet AII (UV-AII) band (∼320-340 nm) at low temperatures. The laser threshold is in the range of tens of amps per centimetre squared, which is nearly three orders of magnitude lower than those of previously reported quantum-well lasers. This work also reports the first demonstration of electrically injected AlGaN-based ultraviolet lasers monolithically grown on a Si substrate, and offers a new avenue for achieving semiconductor lasers in the ultraviolet B (UV-B) (280-320 nm) and ultraviolet C (UV-C) (<280 nm) bands.

Osteopontin mediates an MZF1-TGF-β1-dependent transformation of mesenchymal stem cells into cancer-associated fibroblasts in breast cancer

Interactions between tumor cells and cancer-associated fibroblasts (CAFs) in the tumor microenvironment (TMEN) significantly influence cancer growth and metastasis. Transforming growth factor-β (TGF-β) is known to be a critical mediator of the CAF phenotype, and osteopontin (OPN) expression in tumors is associated with more aggressive phenotypes and poor patient outcomes. The potential link between these two pathways has not been previously addressed. Utilizing in vitro studies using human mesenchymal stem cells (MSCs) and MDA-MB231 (OPN+) and MCF7 (OPN−) human breast cancer cell lines, we demonstrate that OPN induces integrin-dependent MSC expression of TGF-β1 to mediate adoption of the CAF phenotype. This OPN-TGF-β1 pathway requires the transcription factor, myeloid zinc finger 1 (MZF1). In vivo studies with xenotransplant models in NOD-scid mice showed that OPN expression increases cancer growth and metastasis by mediating MSC-to-CAF transformation in a process that is MZF1- and TGF-β1-dependent. We conclude that tumor-derived OPN engenders MSC-to-CAF transformation in the microenvironment to promote tumor growth and metastasis via the OPN-MZF1-TGF-β1 pathway.

The optimal hormonal replacement modality selection for multiple organ procurement from brain-dead organ donors

The management of brain-dead organ donors is complex. The use of inotropic agents and replacement of depleted hormones (hormonal replacement therapy) is crucial for successful multiple organ procurement, yet the optimal hormonal replacement has not been identified, and the statistical adjustment to determine the best selection is not trivial. Traditional pair-wise comparisons between every pair of treatments, and multiple comparisons to all (MCA), are statistically conservative. Hsu's multiple comparisons with the best (MCB) - adapted from the Dunnett's multiple comparisons with control (MCC) - has been used for selecting the best treatment based on continuous variables. We selected the best hormonal replacement modality for successful multiple organ procurement using a two-step approach. First, we estimated the predicted margins by constructing generalized linear models (GLM) or generalized linear mixed models (GLMM), and then we applied the multiple comparison methods to identify the best hormonal replacement modality given that the testing of hormonal replacement modalities is independent. Based on 10-year data from the United Network for Organ Sharing (UNOS), among 16 hormonal replacement modalities, and using the 95% simultaneous confidence intervals, we found that the combination of thyroid hormone, a corticosteroid, antidiuretic hormone, and insulin was the best modality for multiple organ procurement for transplantation.

Improvement of the light extraction efficiency of GaN-based LEDs using rolled-up nanotube arrays

In this paper, we have investigated the effect of rolled-up nanotubes on the light extraction efficiency of GaN-based LEDs using two-dimensional finite element method simulation. The light extraction involves two successive steps, including the coupling from the light source to the tube and the subsequent emission from the tube to the air. Significantly enhanced light extraction efficiency is observed for both TE and TM waves by optimizing the nanotube geometry and dimension as well as the separation between the nanotube and light source. We have further shown that densely packed nanotube arrays can be integrated with GaN-based LEDs to achieve unequivocal improvement of light extraction efficiency over a large surface area. With recent advances in rolled-up micro- and nanotubes, it is expected that this study can offer a potentially flexible, low cost approach to enhance the light extraction of various LED devices.

Improvement of the emission properties from InGaN/GaN dot-in-a-wire nanostructures after treatment in the flowing afterglow of a microwave N₂ plasma

Nominally pure GaN nanowires (NWs) and InGaN/GaN dot-in-a-wire heterostructures were exposed to the flowing afterglow of a N2 microwave plasma and characterized by photoluminescence (PL) spectroscopy. While the band-edge emission from GaN NWs and the GaN matrix of the InGaN/GaN NWs strongly decreased due to the creation of non-radiative recombination centers in the near-surface region, the emission from the InGaN dots strongly increased. PL excitation measurements indicate that such an increase cannot be explained by a plasma-induced shift of the GaN absorption edge. It is rather ascribed to the passivation of grown-in defects and dynamic annealing due to the presence of plasma-generated N atoms and N2 metastables without excessive introduction of ion-induced damage.

p-Type dopant incorporation and surface charge properties of catalyst-free GaN nanowires revealed by micro-Raman scattering and X-ray photoelectron spectroscopy

Micro-Raman scattering and X-ray photoelectron spectroscopy were employed to investigate Mg-doped GaN nanowires. With the increase of Mg doping level, pronounced Mg-induced local vibrational modes were observed. The evolution of longitudinal optical phonon-plasmon coupled mode, together with detailed X-ray photoelectron spectroscopy studies, show that the near-surface region of nanowires can be transformed from weakly n-type to p-type with the increase of Mg doping.

Exciton kinetics, quantum efficiency, and efficiency droop of monolayer MoS₂ light-emitting devices

We have investigated the quantum efficiency of monolayer MoS2 light-emitting devices through detailed temperature and power-dependent photoluminescence studies and rate equation analysis. The internal quantum efficiency can reach 45 and 8.3% at 83 and 300 K, respectively. However, efficiency droop is clearly measured with increasing carrier injection due to the unusually large Auger recombination coefficient, which is found to be ∼10(-24) cm(6)/s at room temperature, nearly 6 orders of magnitude higher than that of conventional bulk semiconductors. The significantly elevated Auger recombination in the emerging two-dimensional (2D) semiconductors is primarily an indirect process and is attributed to the abrupt bounding surfaces and the enhanced correlation, mediated by magnified Coulomb interactions, between electrons and holes confined in a 2D structure.

p-Type InN nanowires

In this Letter, we demonstrate that with the merit of nanowire structure and a self-catalytic growth process p-type InN can be realized for the first time by "direct" magnesium (Mg) doping. The presence of Mg acceptor energy levels in InN is confirmed by photoluminescence experiments, and a direct evidence of p-type conduction is demonstrated unambiguously by studying the transfer characteristics of InN nanowire field effect transistors. Moreover, the near-surface Fermi-level of InN can be tuned from nearly intrinsic to p-type degenerate by controlling Mg dopant incorporation, which is in contrast to the commonly observed electron accumulation on the grown surfaces of Mg-doped InN films. First-principle calculation using the VASP electronic package further shows that the p-type surface formed on Mg-doped InN nanowires is highly stable energetically.

Highly stable photoelectrochemical water splitting and hydrogen generation using a double-band InGaN/GaN core/shell nanowire photoanode

We report on the first demonstration of stable photoelectrochemical water splitting and hydrogen generation on a double-band photoanode in acidic solution (hydrogen bromide), which is achieved by InGaN/GaN core/shell nanowire arrays grown on Si substrate using catalyst-free molecular beam epitaxy. The nanowires are doped n-type using Si to reduce the surface depletion region and increase current conduction. Relatively high incident-photon-to-current-conversion efficiency (up to ~27%) is measured under ultraviolet and visible light irradiation. Under simulated sunlight illumination, steady evolution of molecular hydrogen is further demonstrated.

Highly efficient, spectrally pure 340 nm ultraviolet emission from AlxGa₁-xN nanowire based light emitting diodes

High crystal quality, vertically aligned AlxGa1-xN nanowire based double heterojunction light emitting diodes (LEDs) are grown on Si substrate by molecular beam epitaxy. Such AlxGa1-xN nanowires exhibit unique core-shell structures, which can significantly suppress surface nonradiative recombination. We successfully demonstrate highly efficient AlxGa1-xN nanowire array based LEDs operating at ∼340 nm. Such nanowire devices exhibit superior electrical and optical performance, including an internal quantum efficiency of ∼59% at room temperature, a relatively small series resistance, highly stable emission characteristics, and the absence of efficiency droop under pulsed biasing conditions.

Growth of large-scale vertically aligned GaN nanowires and their heterostructures with high uniformity on SiO(x) by catalyst-free molecular beam epitaxy

The catalyst-free molecular beam epitaxial growth of GaN nanowires and their heterostructures on a SiOx template is studied in detail. It was found that by optimizing the growth temperature, highly uniform and vertically aligned GaN nanowires and InGaN/GaN heterostructures with excellent optical properties can be obtained on a SiOx template in a large-scale. This work provides an entirely new avenue for GaN nanowire based optoelectronic devices.

High efficiency photoelectrochemical water splitting and hydrogen generation using GaN nanowire photoelectrode

We have studied the photoelectrochemical properties of both undoped and Si-doped GaN nanowire arrays in 1 mol l(-1) solutions of hydrogen bromide and potassium bromide, which were used separately as electrolytes. It is observed that variations of the photocurrent with bias voltage depend strongly on the n-type doping in GaN nanowires in both electrolytes, which are analyzed in the context of GaN surface band bending and its variation with the incorporation of Si-doping. Maximum incident-photon-to-current-conversion efficiencies of ~15% and 18% are measured for undoped and Si-doped GaN nanowires under ~350 nm light illumination, respectively. Stable hydrogen generation is also observed at a zero bias potential versus the counter-electrode.

Developmental function in toddlers with sickle cell anemia

BACKGROUND

Neurocognitive impairment occurs in children and adults with sickle cell anemia, but little is known about neurodevelopment in very young children. We examined the neurodevelopmental status of infants participating in the Pediatric Hydroxyurea Phase III Clinical Trial (Baby Hug) to determine relationships with age, cerebral blood flow velocity, and hemoglobin concentration.

METHODS

Standardized measures of infant neurodevelopment were administered to 193 infants with hemoglobin SS or hemoglobin S-β(0) thalassemia between 7 and 18 months of age at the time of their baseline evaluation. Associations between neurodevelopmental scores and age, family income, parent education, hemoglobin concentration, and transcranial Doppler velocity were examined.

RESULTS

Mean functioning on the baseline neurodevelopment scales was in the average range. There were no mental development scores <70 (impaired); 22 children had scores in the clinically significant range, 11 with impaired psychomotor scores and 11 with problematic behavior rating scores. Significantly poorer performance was observed with older age at baseline. Behavior rating scores were an average of 2.82 percentile points lower per month of age, with similar patterns observed with parent report using adaptive behavior scales. Parent-reported functional abilities and hemoglobin were negatively associated with higher transcranial Doppler velocities.

CONCLUSIONS

Whereas overall functioning was in the normal range, behavioral and adaptive function was poorer with older age, even in this very young group of children. Explanatory mechanisms for this association between poorer developmental function and older age need to be identified.

Recombination dynamics in InGaN/GaN nanowire heterostructures on Si(111)

We have performed room-temperature time-resolved photoluminescence measurements on samples that comprise InGaN insertions embedded in GaN nanowires. The decay curves reveal non-exponential recombination dynamics that evolve into a power law at long times. We find that the characteristic power-law exponent increases with emission photon energy. The data are analyzed in terms of a model that involves an interplay between a radiative state and a metastable charge-separated state. The agreement between our results and the model points towards an emission dominated by carriers localized on In-rich nanoclusters that form spontaneously inside the InGaN insertions.

Observation of phonon sideband emission in intrinsic InN nanowires: a photoluminescence and micro-Raman scattering study

In this work, photoluminescence and micro-Raman scattering experiments were performed on undoped InN nanowires. It was found that, besides the main photoluminescence peak, a clear phonon sideband emission peak, with an extremely narrow linewidth ~9 meV, was measured. The phonon spectrum revealed by micro-Raman scattering indicates only uncoupled LO phonons are involved in such phonon sideband emission. The clearly resolved phonon sideband emission peak with a narrow linewidth, together with the uncoupled LO phonon modes, suggests the superior quality of the presented InN nanowires, i.e., extremely low residual electron density and the absence of surface electron accumulation, which is consistent with the physical properties of intrinsic InN nanowires as in the previous studies. The detailed phonon sideband properties are also discussed in the text.

Distinct genes related to drug response identified in ER positive and ER negative breast cancer cell lines

Breast cancer patients have different responses to chemotherapeutic treatments. Genes associated with drug response can provide insight to understand the mechanisms of drug resistance, identify promising therapeutic opportunities, and facilitate personalized treatment. Estrogen receptor (ER) positive and ER negative breast cancer have distinct clinical behavior and molecular properties. However, to date, few studies have rigorously assessed drug response genes in them. In this study, our goal was to systematically identify genes associated with multidrug response in ER positive and ER negative breast cancer cell lines. We tested 27 human breast cell lines for response to seven chemotherapeutic agents (cyclophosphamide, docetaxel, doxorubicin, epirubicin, fluorouracil, gemcitabine, and paclitaxel). We integrated publicly available gene expression profiles of these cell lines with their in vitro drug response patterns, then applied meta-analysis to identify genes related to multidrug response in ER positive and ER negative cells separately. One hundred eighty-eight genes were identified as related to multidrug response in ER positive and 32 genes in ER negative breast cell lines. Of these, only three genes (DBI, TOP2A, and PMVK) were common to both cell types. TOP2A was positively associated with drug response, and DBI was negatively associated with drug response. Interestingly, PMVK was positively associated with drug response in ER positive cells and negatively in ER negative cells. Functional analysis showed that while cell cycle affects drug response in both ER positive and negative cells, most biological processes that are involved in drug response are distinct. A number of signaling pathways that are uniquely enriched in ER positive cells have complex cross talk with ER signaling, while in ER negative cells, enriched pathways are related to metabolic functions. Taken together, our analysis indicates that distinct mechanisms are involved in multidrug response in ER positive and ER negative breast cells.

Tuning the surface charge properties of epitaxial InN nanowires

We have investigated the correlated surface electronic and optical properties of [0001]-oriented epitaxial InN nanowires grown directly on silicon. By dramatically improving the epitaxial growth process, we have achieved, for the first time, intrinsic InN both within the bulk and at nonpolar InN surfaces. The near-surface Fermi-level was measured to be ∼0.55 eV above the valence band maximum for undoped InN nanowires, suggesting the absence of surface electron accumulation and Fermi-level pinning. This result is in direct contrast to the problematic degenerate two-dimensional electron gas universally observed on grown surfaces of n-type degenerate InN. We have further demonstrated that the surface charge properties of InN nanowires, including the formation of two-dimensional electron gas and the optical emission characteristics can be precisely tuned through controlled n-type doping. At relatively high doping levels in this study, the near-surface Fermi-level was found to be pinned at ∼0.95-1.3 eV above the valence band maximum. Through these trends, well captured by the effective mass and ab initio materials modeling, we have unambiguously identified the definitive role of surface doping in tuning the surface charge properties of InN.

p-Type modulation doped InGaN/GaN dot-in-a-wire white-light-emitting diodes monolithically grown on Si(111)

Full-color, catalyst-free InGaN/GaN dot-in-a-wire light-emitting diodes (LEDs) were monolithically grown on Si(111) by molecular beam epitaxy, with the emission characteristics controlled by the dot properties in a single epitaxial growth step. With the use of p-type modulation doping in the dot-in-a-wire heterostructures, we have demonstrated the most efficient phosphor-free white LEDs ever reported, which exhibit an internal quantum efficiency of ∼56.8%, nearly unaltered CIE chromaticity coordinates with increasing injection current, and virtually zero efficiency droop at current densities up to ∼640 A/cm(2). The remarkable performance is attributed to the superior three-dimensional carrier confinement provided by the electronically coupled dot-in-a-wire heterostructures, the nearly defect- and strain-free GaN nanowires, and the significantly enhanced hole transport due to the p-type modulation doping.