Fermi surface of the chiral topological semimetal PtGa.

PtGa is a topological semimetal with giant spin-split Fermi arcs. Here, we report on angular-dependent de Haas-van Alphen (dHvA) measurements combined with band-structure calculations to elucidate the details of the bulk Fermi surface of PtGa. The strong spin-orbit coupling leads to eight bands crossing the Fermi energy that form a multitude of Fermi surfaces with closed extremal orbits and results in very rich dHvA spectra. The large number of experimentally observed dHvA frequencies make the assignment to the equally large number of calculated dHvA orbits challenging. Nevertheless, we find consistency between experiment and calculations verifying the topological character with maximal Chern number of the spin-split Fermi surface.

Observation of giant spin-split Fermi-arc with maximal Chern number in the chiral topological semimetal PtGa.

Non-symmorphic chiral topological crystals host exotic multifold fermions, and their associated Fermi arcs helically wrap around and expand throughout the Brillouin zone between the high-symmetry center and surface-corner momenta. However, Fermi-arc splitting and realization of the theoretically proposed maximal Chern number rely heavily on the spin-orbit coupling (SOC) strength. In the present work, we investigate the topological states of a new chiral crystal, PtGa, which has the strongest SOC among all chiral crystals reported to date. With a comprehensive investigation using high-resolution angle-resolved photoemission spectroscopy, quantum-oscillation measurements, and state-of-the-art ab initio calculations, we report a giant SOC-induced splitting of both Fermi arcs and bulk states. Consequently, this study experimentally confirms the realization of a maximal Chern number equal to ±4 in multifold fermionic systems, thereby providing a platform to observe large-quantized photogalvanic currents in optical experiments.

[Magnetic resonance imaging. Density equalizing mapping analysis of global research architecture]. / Magnetresonanztomographie. Eine Density-equalizing-mapping-Analyse der globalen Forschungsarchitektur.

BACKGROUND: Despite the great medical importance, there is still no comprehensive scientometric analysis regarding the results of magnetic resonance imaging (MRI) and the development of the importance for the healthcare system. AIMS: This paper evaluated and analyzed the entire research publication results on the topic of MRI for the period 1981-2007 based on scientometric methods and parameters. MATERIAL AND METHODS: A scientometric analysis (database: ISI Web of Science 1981-2007, search terms MRI and magnetic resonance imaging) was performed. The following parameters were analyzed: number of publications, countries of publication, number of citations, citation rate and collaborations, using various analytical and display techniques, including density equalizing map projections. RESULTS: Most of the 49,122 publications on MRI could be attributed to the USA (32.5 %), which also has the most cooperative collaborations. Within Europe, Germany (10.3 %) is the country with the highest number of publications followed by the UK (9.3 %). The western industrialized nations dominate over the rest of the world in terms of scientific developments of MRI. The thematic focus of the publications lies in the fields of radiology and neuroscience. In addition to the journal Neurology most scientific articles were published in Magnetic Resonance in Medicine and Circulation. DISCUSSION: The results show that the current trend is continuing and the scientific interest in MRI is continuously increasing.

Fatal poisoning with Taxus baccata: quantification of paclitaxel (taxol A), 10-deacetyltaxol, baccatin III, 10-deacetylbaccatin III, cephalomannine (taxol B), and 3,5-dimethoxyphenol in body fluids by liquid chromatography-tandem mass spectrometry.

This method development was to confirm the fatal ingestion of toxic yew plant material in postmortem samples (stomach content, urine, femoral blood, cardiac blood, bile, and brain tissue) collected from a 22-year-old man who committed suicide by ingesting yew leaves. The analytical method was based on a liquid-liquid extraction under alkaline conditions followed by LC-MS-MS analysis. Chromatographic separation was achieved by HPLC on a Kinetex C18 2.6u (100 × 3 mm) coupled to a QTRAP 5500 system. The method allows the simultaneous identification and quantification of the yew alkaloids taxoids paclitaxel (taxol A), 10-deacetyltaxol, baccatin III, 10-deacetylbaccatin III, cephalomannine (taxol B), and 3,5-dimethoxyphenol; the alkaloidal diterpenoids monoacetyltaxine, taxine B, monohydroxydiacetyltaxine, triacetyltaxine, and monohydroxytriacetyltaxine were also identified. The initial hypothesis of yew tree (Taxus baccata) poisoning was confirmed. The quantitative evaluation revealed taxoid concentrations ranging from 4.5 to 132 µg/L (stomach content), 1 to 200 µg/L (urine), <0.5 to 12 µg/L (cardiac blood), <0.5 to 7.3 µg/L (femoral blood), and 4.9 to 290 µg/L (bile). In brain tissue, none of these taxoids could be detected (<0.5 µg/L). In urine, after enzymatic hydrolysis, the concentration of 3,5-dimethoxyphenol (3,5-DMP) was 23,000 µg/L. The alkaloidal diterpenoids were found in all postmortem samples. The newly developed LC-MS-MS method enables the identification of alkaloidal and non-alkaloidal diterpenoids and 3,5-dimethoxyphenol in human body fluids and tissues for the confirmation of accidental or intentional poisonings with yew plant material.

A rare cause of ulcerative colitis - diarrhoea and perianal bleeding due to posttransplant lymphoproliferative disorder (PTLD).

Post-transplant lymphoproliferative disorder (PTLD) is characterised by frequent extranodal manifestation, in 20 - 25 % including the gastrointestinal tract. This entity, which is more frequent after solid organ transplantation, rarely occurs after bone marrow transplantation (BMT). We report the case of a 43-year-old male presenting with a short history of rectal bleeding, diarrhoea and weight loss. He had received a bone marrow transplant two years previously for an acute lymphocytic leukaemia of B-cell origin. On sigmoidoscopy, deep ulcerations of the rectal and sigmoideal mucosa were found. Further investigations revealed a diffuse infiltration of the liver, spleen, both kidneys and lungs. Histologically, a monomorphic post-transplant lymphoproliferative disorder was diagnosed, the subtype was a high grade diffuse-large cell Non-Hodgkin's lymphoma of B-cell origin. The biopsies showed that a major proportion of cells expressed Epstein-Barr virus encoded proteins typical for latent as well as lytic EBV infection. This is a common feature of PTLD and possibly plays a critical role in its pathogenesis. The current therapeutic approach to the subtype of PTLD we saw in this patient is CHOP chemotherapy, comprising the anti-CD 20 antibody rituximab if CD 20-positivity is present. This patient had a fatal course of the disease and died a few days after the first chemotherapy cycle due to severe multiple organ failure.

A comparative study of five fatal cases of Taxus poisoning.

The study presents five fatal cases of poisoning with Taxus spp., all of which were suicides of young people aged between 16 and 26 years. Yew leaves were consumed in four fatalities, whereas a mash from Taxus was ingested in one case. No relevant concentrations of alcohol, narcotic drugs, and pharmaceuticals were determined in postmortem toxicological screening. At forensic autopsy, a widely dilated pupil was found in two decedents. Furthermore, autopsy showed unspecific findings of intoxication in all cases: acute blood congestion of lungs, liver, kidney, and brain as well as dilated cardiac ventricles. No signs of violence could be found in any of the fatalities. Yew leaves were identified in four cases in the stomach and duodenum. 3,5-Dimethoxyphenol, the aglycon of the Taxus ingredient taxicatine, was determined as toxicological evidence for the absorption of yew ingredients. Taxus intoxication could be confirmed by 3,5-dimethoxyphenol concentrations in cardiac blood between 31 and 528 ng/ml for all cases. 3,5-Dimethoxyphenol was also detected in stomach contents as well as in urine, liver, kidneys, and brain samples. Based on the different concentrations of 3,5-dimethoxyphenol determined in the cardiac blood samples, it was concluded that the form of ingestion plays a decisive role in the process of poisoning. Finally, a toxic range for Taxus poisoning based on 3,5-dimethoxyphenol as marker substance is proposed as orientation.

Memory performance in multiple sclerosis patients correlates with central brain atrophy.

OBJECTIVE: To assess whole brain and central brain atrophy as well as their differential relation to memory, cognitive performance, fatigue, depression and quality of life in patients with relapsing-remitting multiple sclerosis (RRMS). METHODS: A 3D flow compensated gradient recalled T1-weighted MRI was acquired in 45 RRMS patients. An automated analysis tool was used to calculate brain parenchymal fraction (BPF) and ventricular brain fraction (VF). All patients were assessed with neuropsychological tests focusing on memory and self-rating scales for depression, fatigue and quality of life. Age corrected partial correlations between brain atrophy, motor performance, psychological scales and test scores were calculated. RESULTS: BPF correlated moderately (0.3 < or = r < 0.5) with duration of symptoms and disease, the Expanded Disability Status Scale (EDSS), the upper extremity motor performance, and with mental aspects of quality of life. VF correlated moderately with EDSS, upper and lower extremity motor performance and memory functions. Neither BPF nor VF correlated with fatigue and depression. Results of several cognitive tests correlated moderately with depression and fatigue, the Paced Auditory Serial Addition Test (PASAT) showing the largest correlation. CONCLUSIONS: Memory performance shows a correlation with relative ventricular size in RRMS patients, indicating the strategic location of the ventricle system along the structures of the limbic system and its vulnerability in MS. The PASAT and several other cognitive tests show moderate correlations with depression and fatigue, arguing for an inter relation between the cognitive functioning and the emotional state of patients. However, this relation is independent of measurable brain atrophy.

On-site testing of illicit drugs: the use of the drug-testing device "Toxiquick".

Since 1998, driving under the influence of drugs such as amphetamine, MDMA, MDE, cannabis, cocaine, heroine and morphine is sanctioned due to Section 24a of the Road Traffic Regulations of Germany. Therefore, from December 2000 to June 2002 altogether 751 roadside tests with the immunochemical test device Toxiquick were conducted on 302 drivers (273 male and 29 female) on oral fluid samples obtained during control actions in Franconia. The results of the tests are compared to the results obtained through quantification of corresponding blood samples by GC/MS. In general, in 75% the roadside test produced correct results and therefore gave helpful assistance to the police officers into the right direction regarding drug abuse. Except for cannabinoids, the number of false negative results was relatively small, whereas false positive results ranged between 32.2% for opiates and 10.7% for benzoylecgonine.

Application of SERS spectroscopy to the identification of (3,4-methylenedioxy)amphetamine in forensic samples utilizing matrix stabilized silver halides.

A method based on surface-enhanced Raman scattering (SERS) spectroscopy was developed to meet the need for the reliable and rapid identification of illicit drugs such as the 'designer drug' XTC, preferably to increase the security of legal certificates. A matrix stabilized silver halide dispersion on a microtiter plate is used as the SERS-active substrate, providing an easy to use system for sample preparation and probing by means of a Raman microscope. The potential of the method is demonstrated by applying it to the identification of the psychoactive ingredients of drug containing tablets which were confiscated by the local police at techno-music events. The samples of interest were 26 different brands of XTC tablets and several pieces of evidence (powders) containing amphetamine. For reference, we show SERS and Raman spectra of pristine amphetamine, methamphetamine, 3,4-methylenedioxyamphetamine, 3,4-methylenedioxymethamphetamine (MDMA) and 3,4-methylenedioxyethamphetamine.