Transition to the quantum hall regime in InAs nanowire cross-junctions

We present a low-temperature electrical transport study on four-terminal ballistic InAs nanowire cross-junctions in magnetic fields aligned perpendicular to the cross-plane. Two-terminal longitudinal conductance measurements between opposing contact terminals reveal typical 1D conductance quantization at zero magnetic field. As the magnetic field is applied, the 1D bands evolve into hybrid magneto-electric sub-levels that eventually transform into Landau levels for the widest nanowire devices investigated (width = 100 nm). Hall measurements in a four-terminal configuration on these devices show plateaus in the transverse Hall resistance at high magnetic fields that scale with (ve 2 /h) -1 . e is the elementary charge, h denotes Planck's constant and v is an integer that coincides with the Landau level index determined from the longitudinal conductance measurements. While the 1D conductance quantization in zero magnetic field is fragile against disorder at the NW surface, the plateaus in the Hall resistance at high fields remain robust as expected for a topologically protected Quantum Hall phase. © 2019 IOP Publishing Ltd

Intraneuronal pyroglutamate-Abeta 3–42 triggers neurodegeneration and lethal neurological deficits in a transgenic mouse model

It is well established that only a fraction of Aβ peptides in the brain of Alzheimer’s disease (AD) patients start with N-terminal aspartate (Aβ1D) which is generated by proteolytic processing of amyloid precursor protein (APP) by BACE. N-terminally truncated and pyroglutamate modified Aβ starting at position 3 and ending with amino acid 42 [Aβ3(pE)–42] have been previously shown to represent a major species in the brain of AD patients. When compared with Aβ1–42, this peptide has stronger aggregation propensity and increased toxicity in vitro. Although it is unknown which peptidases remove the first two N-terminal amino acids, the cyclization of Aβ at N-terminal glutamate can be catalyzed in vitro. Here, we show that Aβ3(pE)–42 induces neurodegeneration and concomitant neurological deficits in a novel mouse model (TBA2 transgenic mice). Although TBA2 transgenic mice exhibit a strong neuronal expression of Aβ3–42 predominantly in hippocampus and cerebellum, few plaques were found in the cortex, cerebellum, brain stem and thalamus. The levels of converted Aβ3(pE)-42 in TBA2 mice were comparable to the APP/PS1KI mouse model with robust neuron loss and associated behavioral deficits. Eight weeks after birth TBA2 mice developed massive neurological impairments together with abundant loss of Purkinje cells. Although the TBA2 model lacks important AD-typical neuropathological features like tangles and hippocampal degeneration, it clearly demonstrates that intraneuronal Aβ3(pE)–42 is neurotoxic in vivo

Ibrutinib combined with immunochemotherapy with or without autologous stem-cell transplantation versus immunochemotherapy and autologous stem-cell transplantation in previously untreated patients with mantle cell lymphoma (TRIANGLE):a three-arm, randomised, open-label, phase 3 superiority trial of the European Mantle Cell Lymphoma Network

Background: Adding ibrutinib to standard immunochemotherapy might improve outcomes and challenge autologous stem-cell transplantation (ASCT) in younger (aged 65 years or younger) mantle cell lymphoma patients. This trial aimed to investigate whether the addition of ibrutinib results in a superior clinical outcome compared with the pre-trial immunochemotherapy standard with ASCT or an ibrutinib-containing treatment without ASCT. We also investigated whether standard treatment with ASCT is superior to a treatment adding ibrutinib but without ASCT. Methods: The open-label, randomised, three-arm, parallel-group, superiority TRIANGLE trial was performed in 165 secondary or tertiary clinical centres in 13 European countries and Israel. Patients with previously untreated, stage II–IV mantle cell lymphoma, aged 18–65 years and suitable for ASCT were randomly assigned 1:1:1 to control group A or experimental groups A+I or I, stratified by study group and mantle cell lymphoma international prognostic index risk groups. Treatment in group A consisted of six alternating cycles of R-CHOP (intravenous rituximab 375 mg/m2 on day 0 or 1, intravenous cyclophosphamide 750 mg/m2 on day 1, intravenous doxorubicin 50 mg/m2 on day 1, intravenous vincristine 1·4 mg/m2 on day 1, and oral prednisone 100 mg on days 1–5) and R-DHAP (or R-DHAOx, intravenous rituximab 375 mg/m2 on day 0 or 1, intravenous or oral dexamethasone 40 mg on days 1–4, intravenous cytarabine 2 × 2 g/m2 for 3 h every 12 h on day 2, and intravenous cisplatin 100 mg/m2 over 24 h on day 1 or alternatively intravenous oxaliplatin 130 mg/m2 on day 1) followed by ASCT. In group A+I, ibrutinib (560 mg orally each day) was added on days 1–19 of R-CHOP cycles and as fixed-duration maintenance (560 mg orally each day for 2 years) after ASCT. In group I, ibrutinib was given the same way as in group A+I, but ASCT was omitted. Three pairwise one-sided log-rank tests for the primary outcome of failure-free survival were statistically monitored. The primary analysis was done by intention-to-treat. Adverse events were evaluated by treatment period among patients who started the respective treatment. This ongoing trial is registered with ClinicalTrials.gov, NCT02858258. Findings: Between July 29, 2016 and Dec 28, 2020, 870 patients (662 men, 208 women) were randomly assigned to group A (n=288), group A+I (n=292), and group I (n=290). After 31 months median follow-up, group A+I was superior to group A with 3-year failure-free survival of 88% (95% CI 84–92) versus 72% (67–79; hazard ratio 0·52 [one-sided 98·3% CI 0–0·86]; one-sided p=0·0008). Superiority of group A over group I was not shown with 3-year failure-free survival 72% (67–79) versus 86% (82–91; hazard ratio 1·77 [one-sided 98·3% CI 0–3·76]; one-sided p=0·9979). The comparison of group A+I versus group I is ongoing. There were no relevant differences in grade 3–5 adverse events during induction or ASCT between patients treated with R-CHOP/R-DHAP or ibrutinib combined with R-CHOP/R-DHAP. During maintenance or follow-up, substantially more grade 3–5 haematological adverse events and infections were reported after ASCT plus ibrutinib (group A+I; haematological: 114 [50%] of 231 patients; infections: 58 [25%] of 231; fatal infections: two [1%] of 231) compared with ibrutinib only (group I; haematological: 74 [28%] of 269; infections: 52 [19%] of 269; fatal infections: two [1%] of 269) or after ASCT (group A; haematological: 51 [21%] of 238; infections: 32 [13%] of 238; fatal infections: three [1%] of 238). Interpretation: Adding ibrutinib to first-line treatment resulted in superior efficacy in younger mantle cell lymphoma patients with increased toxicity when given after ASCT. Adding ibrutinib during induction and as maintenance should be part of first-line treatment of younger mantle cell lymphoma patients. Whether ASCT adds to an ibrutinib-containing regimen is not yet determined. Funding: Janssen and Leukemia &amp; Lymphoma Society.</p

Distinct glutaminyl cyclase expression in Edinger–Westphal nucleus, locus coeruleus and nucleus basalis Meynert contributes to pGlu-Aβ pathology in Alzheimer’s disease

Glutaminyl cyclase (QC) was discovered recently as the enzyme catalyzing the pyroglutamate (pGlu or pE) modification of N-terminally truncated Alzheimer’s disease (AD) Aβ peptides in vivo. This modification confers resistance to proteolysis, rapid aggregation and neurotoxicity and can be prevented by QC inhibitors in vitro and in vivo, as shown in transgenic animal models. However, in mouse brain QC is only expressed by a relatively low proportion of neurons in most neocortical and hippocampal subregions. Here, we demonstrate that QC is highly abundant in subcortical brain nuclei severely affected in AD. In particular, QC is expressed by virtually all urocortin-1-positive, but not by cholinergic neurons of the Edinger–Westphal nucleus, by noradrenergic locus coeruleus and by cholinergic nucleus basalis magnocellularis neurons in mouse brain. In human brain, QC is expressed by both, urocortin-1 and cholinergic Edinger–Westphal neurons and by locus coeruleus and nucleus basalis Meynert neurons. In brains from AD patients, these neuronal populations displayed intraneuronal pE-Aβ immunoreactivity and morphological signs of degeneration as well as extracellular pE-Aβ deposits. Adjacent AD brain structures lacking QC expression and brains from control subjects were devoid of such aggregates. This is the first demonstration of QC expression and pE-Aβ formation in subcortical brain regions affected in AD. Our results may explain the high vulnerability of defined subcortical neuronal populations and their central target areas in AD as a consequence of QC expression and pE-Aβ formation

Alzheimer disease models and human neuropathology: similarities and differences

Animal models aim to replicate the symptoms, the lesions or the cause(s) of Alzheimer disease. Numerous mouse transgenic lines have now succeeded in partially reproducing its lesions: the extracellular deposits of Aβ peptide and the intracellular accumulation of tau protein. Mutated human APP transgenes result in the deposition of Aβ peptide, similar but not identical to the Aβ peptide of human senile plaque. Amyloid angiopathy is common. Besides the deposition of Aβ, axon dystrophy and alteration of dendrites have been observed. All of the mutations cause an increase in Aβ 42 levels, except for the Arctic mutation, which alters the Aβ sequence itself. Overexpressing wild-type APP alone (as in the murine models of human trisomy 21) causes no Aβ deposition in most mouse lines. Doubly (APP × mutated PS1) transgenic mice develop the lesions earlier. Transgenic mice in which BACE1 has been knocked out or overexpressed have been produced, as well as lines with altered expression of neprilysin, the main degrading enzyme of Aβ. The APP transgenic mice have raised new questions concerning the mechanisms of neuronal loss, the accumulation of Aβ in the cell body of the neurons, inflammation and gliosis, and the dendritic alterations. They have allowed some insight to be gained into the kinetics of the changes. The connection between the symptoms, the lesions and the increase in Aβ oligomers has been found to be difficult to unravel. Neurofibrillary tangles are only found in mouse lines that overexpress mutated tau or human tau on a murine tau −/− background. A triply transgenic model (mutated APP, PS1 and tau) recapitulates the alterations seen in AD but its physiological relevance may be discussed. A number of modulators of Aβ or of tau accumulation have been tested. A transgenic model may be analyzed at three levels at least (symptoms, lesions, cause of the disease), and a reading key is proposed to summarize this analysis

Group IV Epitaxy for Advanced Nano- and Optoelectronic Applications

Sn-based group IV semiconductors have attracted increasing scientific interest during the last decade due to their exciting electronic properties, such as a fundamental direct bandgap or high carrier mobility. Whereas these properties have been predicted already in the early 1980’s, the quality of epitaxially grown GeSn and SiGeSn layers on Si and Ge substrates has been limited owing to the low solid solubility of Sn in (Si)Ge (15 %). Hence, the enormous potential of these material systems regarding its implementation in nano- and optoelectronics has not been exploited to date. A low temperature reduced pressure chemical vapour process using commercially available Ge- and Sn-precursors, namely Ge$_{2}$H$_{6}$ and SnCl$_{4}$, is developed for the growth of GeSn and SiGeSn epilayers directly on Si(001) and on Ge-buffered Si(001). Sn concentrations far beyond the solid solubility of Sn in (Si)Ge are achieved. High growth rates at low growth temperatures assure exceptionally high monocrystalline quality evidenced by exhaustive layer characterization, i.e. transmission electron microscopy, Rutherford backscattering spectrometry, X-ray diffraction or photoluminescence. Moreover, it is shown that the plastic strain relaxation of these (Si)GeSn epilayers on Ge/Si(001) takes place mostly via edge dislocations rather than via threading dislocations as well-known in other group IV systems, i.e. SiGe/Ge. Subsequently, dedicated heterostructures are used for admittance and optical characterization. Highly biaxially tensile strained Ge and GeSn layers grown on GeSn strain relaxed buffer layers are used to fabricate metal oxide semiconductor capacitors in order to investigate the interfacial quality between these narrow bandgap semiconductors and high-k dielectrics. For the investigation of the Nickel metallization process of GeSn and SiGeSn epilayers, Sn concentration above 10 at.% are used. Furthermore, the transition from an indirect to a fundamental direct group IV semiconductor is presented by means of temperature dependent PL measurements on a set of high Sn content GeSn epilayers. Strain relaxed GeSn layers with a Sn concentration of 12.6 at.% grown on Si(001) substrates exhibit high modal gain values at cryogenic temperatures. Finally, the first demonstration of lasing action in direct bandgap group IV Fabry-Perot cavities is presented