Observation of Seven Astrophysical Tau Neutrino Candidates with IceCube

We report on a measurement of astrophysical tau neutrinos with 9.7 yr of IceCube data. Using convolutional neural networks trained on images derived from simulated events, seven candidate ν_{τ} events were found with visible energies ranging from roughly 20 TeV to 1 PeV and a median expected parent ν_{τ} energy of about 200 TeV. Considering backgrounds from astrophysical and atmospheric neutrinos, and muons from π^{±}/K^{±} decays in atmospheric air showers, we obtain a total estimated background of about 0.5 events, dominated by non-ν_{τ} astrophysical neutrinos. Thus, we rule out the absence of astrophysical ν_{τ} at the 5σ level. The measured astrophysical ν_{τ} flux is consistent with expectations based on previously published IceCube astrophysical neutrino flux measurements and neutrino oscillations.

National resident survey in dermatopathology: The role of slide scanners in resident learning

BACKGROUND

Dermatology residents gain exposure to dermatopathology through a variety of educational modalities. While virtual pathology applications have risen dramatically, resident utilization of digital libraries, slide scanner availability, and comfort with virtual slides are not well-known. This study aims to assess the current landscape of educational resources used by dermatology residents.

METHODS

A 17-question survey was sent to dermatology residents through a national email database. The survey was a self-assessment of their experience in dermatopathology education and the use of departmental slide scanners.

RESULTS

The use of digital dermatopathology is high among trainees, despite only half of respondents reporting slide scanner access. Residents report using virtual images more often in non-clinical dermatopathology didactics and independent studies compared to clinical dermatopathology rotations. Public slide set use was common, while professional society and departmental slide sets may be underutilized. Over half of respondents report being extremely or very comfortable navigating interactive scanned slides.

CONCLUSIONS

Survey data suggests digital slides are currently predominantly used in non-clinical dermatopathology rotations and independent studies. Incorporation of slide scanners into departments may benefit resident education through the development of high-quality, curated departmental slide sets.

Observation of high-energy neutrinos from the Galactic plane

The origin of high-energy cosmic rays, atomic nuclei that continuously impact Earth's atmosphere, is unknown. Because of deflection by interstellar magnetic fields, cosmic rays produced within the Milky Way arrive at Earth from random directions. However, cosmic rays interact with matter near their sources and during propagation, which produces high-energy neutrinos. We searched for neutrino emission using machine learning techniques applied to 10 years of data from the IceCube Neutrino Observatory. By comparing diffuse emission models to a background-only hypothesis, we identified neutrino emission from the Galactic plane at the 4.5σ level of significance. The signal is consistent with diffuse emission of neutrinos from the Milky Way but could also arise from a population of unresolved point sources.

Evidence for neutrino emission from the nearby active galaxy NGC 1068

A supermassive black hole, obscured by cosmic dust, powers the nearby active galaxy NGC 1068. Neutrinos, which rarely interact with matter, could provide information on the galaxy’s active core. We searched for neutrino emission from astrophysical objects using data recorded with the IceCube neutrino detector between 2011 and 2020. The positions of 110 known gamma-ray sources were individually searched for neutrino detections above atmospheric and cosmic backgrounds. We found that NGC 1068 has an excess of 79 − 20 + 22 neutrinos at tera–electron volt energies, with a global significance of 4.2σ, which we interpret as associated with the active galaxy. The flux of high-energy neutrinos that we measured from NGC 1068 is more than an order of magnitude higher than the upper limit on emissions of tera–electron volt gamma rays from this source.

Search for Unstable Sterile Neutrinos with the IceCube Neutrino Observatory

We present a search for an unstable sterile neutrino by looking for a resonant signal in eight years of atmospheric ν_{μ} data collected from 2011 to 2019 at the IceCube Neutrino Observatory. Both the (stable) three-neutrino and the 3+1 sterile neutrino models are disfavored relative to the unstable sterile neutrino model, though with p values of 2.8% and 0.81%, respectively, we do not observe evidence for 3+1 neutrinos with neutrino decay. The best-fit parameters for the sterile neutrino with decay model from this study are Δm_{41}^{2}=6.7_{-2.5}^{+3.9}  eV^{2}, sin^{2}2θ_{24}=0.33_{-0.17}^{+0.20}, and g^{2}=2.5π±1.5π, where g is the decay-mediating coupling. The preferred regions of the 3+1+decay model from short-baseline oscillation searches are excluded at 90% C.L.

Strong Constraints on Neutrino Nonstandard Interactions from TeV-Scale ν_{μ} Disappearance at IceCube

We report a search for nonstandard neutrino interactions (NSI) using eight years of TeV-scale atmospheric muon neutrino data from the IceCube Neutrino Observatory. By reconstructing incident energies and zenith angles for atmospheric neutrino events, this analysis presents unified confidence intervals for the NSI parameter ε_{μτ}. The best-fit value is consistent with no NSI at a p value of 25.2%. With a 90% confidence interval of -0.0041≤ε_{μτ}≤0.0031 along the real axis and similar strength in the complex plane, this result is the strongest constraint on any NSI parameter from any oscillation channel to date.

Search for Relativistic Magnetic Monopoles with Eight Years of IceCube Data

We present an all-sky 90% confidence level upper limit on the cosmic flux of relativistic magnetic monopoles using 2886 days of IceCube data. The analysis was optimized for monopole speeds between 0.750c and 0.995c, without any explicit restriction on the monopole mass. We constrain the flux of relativistic cosmic magnetic monopoles to a level below 2.0×10^{-19}  cm^{-2} s^{-1} sr^{-1} over the majority of the targeted speed range. This result constitutes the most strict upper limit to date for magnetic monopoles with β≳0.8 and up to β∼0.995 and fills the gap between existing limits on the cosmic flux of nonrelativistic and ultrarelativistic magnetic monopoles.

Fast Evaluation of Herbal Substance Class Composition by Relative Mass Defect Plots

A holistic, nontargeted mass spectrometric analysis of any herbal material and preparation is intimately connected to fast chemical profiling and visualization of secondary plant metabolite classes or single compounds. High-resolution mass spectral data enable a broad variety of analytical possibilities. Often a fast and comprehensive overview on compound classes (phytochemical profiling) is needed before single-substance considerations. We present a fast approach for the initial characterization and substance class profiling using relative mass defect plots for the visualization of herbal compositions. From a dataset of 1160 common plant metabolites that represent a varied mixture of molecular classes in polarity, glycosylation, and alkylation, manually annotated for substance classes, the relative mass defects were calculated using theoretical molecular masses. For the calculation of the relative mass defect, a new approach incorporating two correction functions to obtain correct relative mass defect results also for large hydrocarbons, and a multitude of polyhalogenated molecules was developed. Using the Khachyan algorithm, elliptical areas clustering substance classes within the relative mass defect plots were calculated. The resulting novel relative mass defect plots provide a quick way of two-dimensional substance class mapping directly from high-resolution mass spectral data and may be considered as a unique fingerprint for herbals, part of them or herbal preparations. We show that adding the retention time as a third dimension improves the resolution power of the two-dimensional relative mass defect plot and offers the possibility for a more detailed substance class mapping.

Abstract 2050: Tumor stage-dependent transcriptomic signatures of endothelial cells reveal an intense paracrine crosstalk in liver capillarization

Introduction:

The liver blood vessel network, consisting of liver sinusoidal endothelial cells (LSECs) and capillary endothelial cells (CECs), undergoes distinct modifications in the process of liver cancer development. The selective expansion of the CEC compartment is thereby the most prominent modification leading to a change of the predominant endothelial phenotype. An in depth molecular analysis of the dynamic vascular modifications in hepatocellular carcinoma (HCC) is however still missing.

Methods:

An inducible mouse model with hepatocyte-specific expression of constitutively active yes-associated protein (YAPS127A) was used for stage dependent purification of endothelial cells. Cell sorting allowed the subtyping of liver endothelial cells into LSECs (CD31+, CD146+, Lyve-1+) and CECs (CD31+, CD146+, Lyve-1-) followed by their consecutive transcriptomic analysis. Predicted paracrine interactions were functionally tested in the endothelial cell line SVEC4-10. Gene expression data of 242 HCC patients were used to confirm the findings in human HCC (Roessler et al. 2010).

Results

Immunofluorescence revealed a progressive replacement of LSECs by CECs in livers, hyperplastic lesions, and HCC derived from YAPS127A mice. FACS analysis confirmed the selective expansion of CECs from 4±2% in healthy livers to 37±16% in hepatomegaly to 61±30% in tumor-bearing livers. Expression profiling of CECs and LSECs revealed dynamic CEC-selective changes in early and late phases of hepatocarcinogenesis including an enrichment of migration specific pathways. Phylogenetic tree analysis of the gene set “cytokine –cytokine receptor interaction” displayed endothelial cell (EC)- and stage-specific secretion patterns suggesting a dynamic crosstalk between the EC populations. The promigratory role of the identified HGF/c-Met axis was confirmed in vitro by single cell tracking and spheroid sprouting. In vivo the inhibition through the c-Met inhibitor Cabozantinib led to a 67% reduction of CEC sprouting, in line with with decreased tumor cell proliferation. Human HCC gene expression data from 242 HCC patients confirmed the prognostic relevance of an identified 19 gene capillarization signature.

Conclusions

Our results illustrate a dynamic crosstalk between the two major EC populations in the process of liver tumor development, already detectable in early phases of capillarization. The identified HGF/c-Met axis represents an essential signal pathway in the process of arterial branch elongation and its inhibition through clinically relevant c-Met inhibitors may represent a promising approach to perturbate disease-associated capillarization.

References

Weiler SME, et al., Gastroenterology, 2017. 152(8): p. 2037-2051 e22

Roessler S, et al., Cancer Res. 2010 Dec 15;70(24):10202-12

Citation Format: Stefan Thomann, Sofia Weiler, Martin Dittmer, Daniel Kazdal, Simone Marquard, Stephanie Roessler, Carsten Sticht, Norbert Gretz, Carolin Mogler, Claudia Ball, Hanno Glimm, Eduard Ryschich, Peter Schirmacher, Kai Breuhahn. Tumor stage-dependent transcriptomic signatures of endothelial cells reveal an intense paracrine crosstalk in liver capillarization [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2050.

Hemoglobin S and C affect protein export in Plasmodium falciparum-infected erythrocytes

Malaria is a potentially deadly disease. However, not every infected person develops severe symptoms. Some people are protected by naturally occurring mechanisms that frequently involve inheritable modifications in their hemoglobin. The best studied protective hemoglobins are the sickle cell hemoglobin (HbS) and hemoglobin C (HbC) which both result from a single amino acid substitution in β-globin: glutamic acid at position 6 is replaced by valine or lysine, respectively. How these hemoglobinopathies protect from severe malaria is only partly understood. Models currently proposed in the literature include reduced disease-mediating cytoadherence of parasitized hemoglobinopathic erythrocytes, impaired intraerythrocytic development of the parasite, dampened inflammatory responses, or a combination thereof. Using a conditional protein export system and tightly synchronized Plasmodium falciparum cultures, we now show that export of parasite-encoded proteins across the parasitophorous vacuolar membrane is delayed, slower, and reduced in amount in hemoglobinopathic erythrocytes as compared to parasitized wild type red blood cells. Impaired protein export affects proteins targeted to the host cell cytoplasm, Maurer's clefts, and the host cell plasma membrane. Impaired protein export into the host cell compartment provides a mechanistic explanation for the reduced cytoadherence phenotype associated with parasitized hemoglobinopathic erythrocytes.

Multiple drugs compete for transport via the Plasmodium falciparum chloroquine resistance transporter at distinct but interdependent sites

Mutations in the "chloroquine resistance transporter" (PfCRT) are a major determinant of drug resistance in the malaria parasite Plasmodium falciparum. We have previously shown that mutant PfCRT transports the antimalarial drug chloroquine away from its target, whereas the wild-type form of PfCRT does not. However, little is understood about the transport of other drugs via PfCRT or the mechanism by which PfCRT recognizes different substrates. Here we show that mutant PfCRT also transports quinine, quinidine, and verapamil, indicating that the protein behaves as a multidrug resistance carrier. Detailed kinetic analyses revealed that chloroquine and quinine compete for transport via PfCRT in a manner that is consistent with mixed-type inhibition. Moreover, our analyses suggest that PfCRT accepts chloroquine and quinine at distinct but antagonistically interacting sites. We also found verapamil to be a partial mixed-type inhibitor of chloroquine transport via PfCRT, further supporting the idea that PfCRT possesses multiple substrate-binding sites. Our findings provide new mechanistic insights into the workings of PfCRT, which could be exploited to design potent inhibitors of this key mediator of drug resistance.

Substantial increase in mutations in the genes pfdhfr and pfdhps puts sulphadoxine-pyrimethamine-based intermittent preventive treatment for malaria at risk in Burkina Faso

OBJECTIVE

Sulphadoxine-pyrimethamine (SP) is widely used as intermittent preventive treatment (IPT) for malaria in pregnant women in Sub-Saharan Africa. There are reports of wide-spread SP resistance in countries where SP had once been used as a first-line treatment. It is unclear whether the development of SP resistance also affects countries where SP is mainly used in the context of IPT, as is the case in Burkina Faso. To assess the efficacy of SP-based IPT, we monitored the prevalence of SP conferring genetic mutations in the genes dhfr and dhps in Plasmodium falciparum populations in a rural area of Burkina Faso over a period of 13 years.

METHODS

Molecular epidemiological study consisted of six consecutive cross-sectional surveys of rainy and dry seasons (2009-2012). Data from the rainy season in 2000 served as a baseline. Mutations in dhfr and dhps associated with SP resistance were analysed by pyrosequencing in 861 parasite-positive samples.

RESULTS

The prevalence of the SP resistance conferring triple dhfr mutation 51I, 59R, 108N increased from 1.3% in the rainy season of 2000 to 35.3% in 2009, and 54.3% in 2011 (P ≤ 0.001). Comparing rainy and dry seasons, we observed an increasing step-like pattern with higher prevalence of the dhfr triple mutant in the respective dry season compared with the preceding rainy season. The proportion of the dhps 437Gly mutation in the rainy season of 2000 was 53.2% and subsequently increased to 77.6% in 2009 (P ≤ 0.001).

CONCLUSION

The increase in molecular markers linked with SP resistance jeopardises the efficacy of IPTp and the planned IPTi interventions in Burkina Faso, calling for careful monitoring of genotypic resistance markers and in vivo validation of IPT efficacy.

Haemoglobin S and C affect the motion of Maurer's clefts in Plasmodium falciparum-infected erythrocytes

The haemoglobinopathies S and C protect carriers from severe Plasmodium falciparum malaria. We have recently shown that haemoglobin S and C interfere with host-actin remodelling in parasitized erythrocytes and the generation of an actin network that seems to be required for vesicular protein trafficking from the Maurer's clefts (a parasite-derived intermediary protein secretory organelle) to the erythrocyte surface. Here we show that the actin network exerts skeletal functions by anchoring the Maurer's clefts within the erythrocyte cytoplasm. Using a customized tracking tool to investigate the motion of single Maurer's clefts, we found that a functional actin network restrains Brownian motion of this organelle. Maurer's clefts moved significantly faster in wild-type erythrocytes treated with the actin depolymerizing agent cytochalasin D and in erythrocytes containing the haemoglobin variants S and C. Our data support the model of an impaired actin network being an underpinning cause of cellular malfunctioning in parasitized erythrocytes containing haemoglobin S or C, and, possibly, for the protective role of these haemoglobin variants against severe malaria.

Aspergillus PCR testing: results from a prospective PCR study within the AmBiLoad trial

OBJECTIVES

Invasive fungal infection (IFI) is a major cause of morbidity and mortality in severely immunocompromised patients and is difficult to diagnose. The significance of molecular methods for diagnosis of IFI is still controversial. In a subset of patients treated within the AmBiLoad Trial, samples were investigated prospectively by a nested Aspergillus PCR assay to re-evaluate the significance of PCR in this setting.

PATIENTS AND METHODS

In the randomized, prospective multicenter AmBiLoad trial, patients with proven or probable IFI were randomized to receive liposomal amphotericin B (L-AMB) 3 or 10 mg/kg QD for 14 d followed by L-AMB 3 mg/kg QD. From 91 patients, 459 serial samples (98% blood samples) were investigated by a nested PCR assay for Aspergillus DNA. All samples were investigated in our laboratory with a previously described nested and a quantitative PCR assay. As required by the study protocol, serial Aspergillus antigen galactomannan was performed. IFI was defined according to modified EORTC/MSG 2002 criteria as applied in the AmBiLoad trial.

RESULTS

Seven and 52 patients had proven and probable IFI according to modified EORTC/MSG criteria, respectively. The median number of samples investigated per patient was 4. Seventy percent of samples were obtained during treatment with antifungal study medication. Forty-three samples gave positive PCR results. Patients with an unfavorable outcome had a significantly higher rate of positive PCR results (48% versus 21%).

CONCLUSIONS

The sensitivity of Aspergillus PCR testing is limited during antifungal therapy. The tendency for persistently positive PCR results to indicate a poor prognosis has to be confirmed in further studies.

Liposomales Amphotericin B bei schweren systemischen Mykosen

BACKGROUND

Activity and efficacy of liposomal amphotericin B have been established for the treatment of severe fungal infections. Nephrotoxic side effects, especially during prolonged administration, are regarded as a major disadvantage. In this study we examined the response rates and side effects, particularly nephrotoxicity, of treatment with liposomal amphotericin B in a large cohort of patients.

PATIENTS AND METHODS

406 patients treated with liposomal amphotericin B between January 1999 and August 2003 in participating German hospitals were included. Documentation included demographic and clinical data, reason for the treatment with liposomal amphotericin B, length of treatment, response to antifungal treatment and side effects.

RESULTS

42.4% of the 406 patients were females. Their ages ranged from 1 day to 77 years. 83 % of the patients had malignancies and 65.5 % had fever of unknown origin (FUO). Mean duration of treatment with liposomal amphotericin B was 20 +/- 20 days, at an average dose of 2.3 mg/kg/d. 209 patients (51.5 %) showed complete response (CR),105 patients (25.9 %) partial response (PR) and 51 (12.6 %) patients died during the observation. 80.0 % of patients with FUO showed complete or partial response of symptoms. Mean serum creatinine increased from 0.9 mg/kg before start of therapy with liposomal amphotericin B to 1.1 mg/kg during treatment. Side effects (common toxicity criteria > grade 1) occurred in 94 patients (23/2 %). Among these hypokalemia (6.2 %) and liver damage (5,2 %) were the most common. Nephrotoxicity was documented in 17 patients (4.2 %).

CONCLUSION

Liposomal amphotericin B is a safe and efficacious antifungal drug in the treatment of severe invasive fungal infections and fever of unknown origin. Nephrotoxicity is usually not a limiting factor when using liposomal amphotericin B, if it is administered in approved dosage.

Innovative procedure for the determination of gross-alpha/gross-beta activities in drinking water

An alternative sample preparation method for the determination of gross-alpha/beta activity concentrations in drinking water is introduced in this paper. After the freeze-drying of tap water samples, determination by liquid scintillation counting can be applied utilizing alpha/beta separation. It has been shown that there is no adsorption or loss of solid radionuclides during the freeze-drying procedure. However, the samples have to be measured quickly after the preparation since the ingrowth of daughter isotopes negatively effects the measurement. The limits of detection for gross-alpha and gross-beta activity are in the range 25-210 mBq/l, respectively, for a measurement time of only 8-9 h.