Field-Tunable Berezinskii-Kosterlitz-Thouless Correlations in a Heisenberg Magnet.

We report the manifestation of field-induced Berezinskii-Kosterlitz-Thouless (BKT) correlations in the weakly coupled spin-1/2 Heisenberg layers of the molecular-based bulk material [Cu(pz)_{2}(2-HOpy)_{2}](PF_{6})_{2}. At zero field, a transition to long-range order occurs at 1.38 K, caused by a weak intrinsic easy-plane anisotropy and an interlayer exchange of J^{'}/k_{B}≈1 mK. Because of the moderate intralayer exchange coupling of J/k_{B}=6.8 K, the application of laboratory magnetic fields induces a substantial XY anisotropy of the spin correlations. Crucially, this provides a significant BKT regime, as the tiny interlayer exchange J^{'} only induces 3D correlations upon close approach to the BKT transition with its exponential growth in the spin-correlation length. We employ nuclear magnetic resonance measurements to probe the spin correlations that determine the critical temperatures of the BKT transition as well as that of the onset of long-range order. Further, we perform stochastic series expansion quantum Monte Carlo simulations based on the experimentally determined model parameters. Finite-size scaling of the in-plane spin stiffness yields excellent agreement of critical temperatures between theory and experiment, providing clear evidence that the nonmonotonic magnetic phase diagram of [Cu(pz)_{2}(2-HOpy)_{2}](PF_{6})_{2} is determined by the field-tuned XY anisotropy and the concomitant BKT physics.

Monovacancy paramagnetism in neutron-irradiated graphite probed by 13C NMR.

We report on the magnetic properties of monovacancy defects in neutron-irradiated graphite, probed by 13C nuclear magnetic resonance spectroscopy. The bulk paramagnetism of the defect moments is revealed by the temperature dependence of the NMR frequency shift and spectral linewidth, both of which follow a Curie behavior, in agreement with measurements of the macroscopic magnetization. Compared to pristine graphite, the fluctuating hyperfine fields generated by the defect moments lead to an enhancement of the 13C nuclear spin-lattice relaxation rate [Formula: see text] by about two orders of magnitude. With an applied magnetic field of 7.1 T, the temperature dependence of [Formula: see text] below about 10 K can well be described by a thermally activated form, [Formula: see text], yielding a singular Zeeman energy of ([Formula: see text]) meV, in excellent agreement with the sole presence of polarized, non-interacting defect moments.

Field-stepped broadband NMR in pulsed magnets and application to SrCu2(BO3)2 at 54T.

Pulsed magnets generate the highest magnetic fields as brief transients during which the observation of NMR is difficult, however, this is the only route to unique insight into material properties up to the regime of 100T. Here, it is shown how rather broad NMR spectra can be assembled in a pulsed magnet during a single field pulse by using the inherent time dependence of the field for the recording of field-stepped free induction decays that cover a broad frequency range. The technique is then applied to (11)B NMR of the spin-dimer system SrCu2(BO3)2, a magnetic insulator known to undergo a series of field-driven changes of the magnetic ground state. At peak fields of about 54T at the Dresden High Magnetic Field Laboratory, (11)B NMR spectra spanning a total of about 9MHz width are reconstructed. The results are in good accordance with a change from a high-temperature paramagnetic state to a low-temperature commensurate superstructure of field-induced spin-dimer triplets.

Microscopic Study of the Fulde-Ferrell-Larkin-Ovchinnikov State in an All-Organic Superconductor.

Quasi-two-dimensional superconductors with a sufficiently weak interlayer coupling allow magnetic flux to penetrate in the form of Josephson vortices for in-plane applied magnetic fields. A consequence is the dominance of the Zeeman interaction over orbital effects. In the clean limit, the normal state is favored over superconductivity for fields greater than the paramagnetic limiting field, unless an intermediate, inhomogeneous state is stabilized. Presented here are nuclear magnetic resonance (NMR) studies of the inhomogeneous Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state for ß''-(ET)2SF5CH2CF2SO3. The uniform superconductivity-FFLO transition is identified at an applied field value of 9.3(0.1) T at low temperature (T=130 mK), and evidence for a possible second transition between inhomogeneous states at ∼11 T is presented. The spin polarization distribution inferred from the NMR absorption spectrum compares favorably to a single-Q modulation of the superconducting order parameter.

NMR shift and relaxation measurements in pulsed high-field magnets up to 58T.

Nuclear magnetic resonance (NMR) experiments at fields up to 58T in pulsed magnets at the Dresden High Magnetic Field Laboratory are reported. The challenge to resolve NMR shifts in these time-dependent fields is addressed for the first time, and it is shown that this can indeed be accomplished with high precision with an internal reference. As a result, signal averaging is possible during a single magnetic field pulse, but also for multiple pulses. Thus, even very weak signals can in principle be recorded and their shifts can be determined. In a second set of experiments, the measurement of nuclear relaxation is investigated. Using adiabatic inversion with the inherent time dependence of the magnetic field and small-angle inspection, it is shown that relaxation measurements are possible, as well. The shift experiments were performed with (27)Al NMR on a mixture of aluminum metal and a Linde type A zeolite. For the relaxation studies, (27)Al NMR and (69)Ga NMR on the metals aluminum and gallium were preformed, respectively.

Vitamin D is not linked to folate status and mRNA expression of intestinal proton-coupled folate transporter.

PURPOSE: In vitro studies discovered intestinal proton-coupled folate transporter (PCFT) as a vitamin D hormone-responsive gene. In vivo effects of vitamin D on PCFT and folate status are currently not available. METHODS: Three experiments were conducted. At first, vitamin D receptor knockout (VDR(-/-)) mice and corresponding wild-type (WT) mice were compared for their plasma and hepatic folate concentration and PCFT mRNA expression in intestinal mucosa. In a second experiment with rats, we analyzed the folate status of offspring in response to a maternal vitamin D-adequate (1,000 IU/kg) or vitamin D-deficient (0 IU/kg) diet that was fed for 11 weeks. Finally, the plasma folate concentration of healthy individuals was studied at baseline (in winter) and in response to an oral treatment for 8 weeks with 2,000 IU vitamin D3 per day or a placebo, respectively. RESULTS: Here, we show that folate status and intestinal PCFT mRNA abundance did not differ between the VDR(-/-) and the WT mice. No effect of vitamin D on folate status was also found in rat dams and their offspring, and plasma folate levels of individuals did not change in response to vitamin D. CONCLUSIONS: Current data from studies with model animals and humans provide no indication for a vitamin D effect on intestinal uptake and status of folate.

[Unclear per anum bleeding during pregnancy]. / Unklare peranale Blutung in der Schwangerschaft.

A 30-year-old, 7-months pregnant woman presented with per anum bleeding. Rectoscopy showed the cause to be a polyp the size of a fingertip 9 cm from the anus. Since the bleeding stopped spontaneously and therefore the need for radical intervention, and due to the advanced pregnancy stage, no biopsy was done. About 1 year later, the same patient experienced sharp pains and anal bleeding during defecation. A poorly defined neuroendocrine carcinoma was diagnosed. Seeking a prognosis optimal for the newborn child, the interdisciplinary decision was made for primary surgery with adjuvant chemotherapy. Other options for this malignancy during and after pregnancy are also discussed.

Use of EPR spectroscopy to study macromolecular structure and function.

Electron paramagnetic resonance (EPR) spectroscopy is now part of the armory available to probe the structural aspects of proteins, nucleic acids and protein-nucleic acid complexes. Since the mobility of a spin label covalently attached to a macromolecule is influenced by its microenvironment, analysis of the EPR spectra of site-specifically incorporated spin labels (probes) provides a powerful tool for investigating structure-function correlates in biological macromolecules. This technique has become readily amenable to address various problems in biology in large measure due to the advent of techniques like site-directed mutagenesis, which enables site-specific substitution of cysteine residues in proteins, and the commercial availability of thiol-specific spin-labeling reagents (Figure 1). In addition to the underlying principle and the experimental strategy, several recent applications are discussed in this review.

Distinct effects of LDL apheresis by hemoperfusion (DALI) and heparin-induced extracorporeal precipitation (HELP) on leukocyte respiratory burst activity of patients with familial hypercholesterolemia.

Hypercholesterolemia and oxidative stress are major risk factors in atherogenesis. In the last years, lipid apheresis has been established as an effective clinical therapy by lowering not only elevated plasma low-density lipoprotein (LDL) levels but also by reducing the incidence of cardiovascular events. The aim of the present study was to investigate peripheral leukocyte oxidant generation in patients with familial hypercholesterolemia (FH) undergoing regular LDL apheresis. The activity state of leukocytes was estimated prior to, immediately after, and 2 days after LDL apheresis carried out by two distinct techniques: hemoperfusion with the DALI system and heparin-induced extracorporeal LDL precipitation (HELP). Oxidant generating activity was measured by chemiluminescence (CL) in whole blood and isolated polymorphonuclear leukocytes (PMNL). The results of our study show increased baseline respiratory burst activities in FH patients as compared to healthy controls. Apheresis with the HELP system was followed by increases in leukocyte count, zymosan-induced whole blood CL, and plasma PMNL elastase levels. The DALI technique caused no changes in leukocyte count and elastase levels and decreased whole blood CL activity. Two days after lipid removal the observed changes returned to pre-apheresis levels. Leukocyte activity parameters before and after apheresis did not correlate with the corresponding plasma levels of triglycerides, total cholesterol, and LDL cholesterol, suggesting that different handling in the framework of both apheresis techniques rather than lipid profile changes during therapy accounted for leukocyte activity modulation.

[Contribution of Berlin clinics and especially the Charité to the development of modern anesthesia in Germany]. / Der Beitrag der Berliner Kliniken und speziell der Charité zur Entwicklung der modernen Anästhesie in Deutschland.

Soon after announcement of the first American ether anesthesias in 1846 one started to anesthetize with ether in Europe. The first ether anesthesia in Germany took place on January 24th, 1947, and was given by Johann Ferdinand Heyfelder in Erlangen. Two weeks later the first ether anesthesia in Berlin was given on February 6th, 1847, by the orthopaedic surgeon Heimann-Wolff Berend. On February 12th, 1847, the surgeon Johann Friedrich Dieffenbach used ether to anesthetize a patient in the Berlin university hospital. Still in 1847 he published his book "The Ether against Pain" which used to be the standard textbook of anesthesia in Germany for many years to come. On February 15th, 1847, Johann Christian Jüngken operated his first patient under ether anesthesia in the surgical department of the Charité hospital assisted by Rudolf Virchow. Since then several famous Berlin surgeons influenced the development of modern anesthesia until the middle of the 20th century. The nitrous oxide bottle was introduced into practice by the Barth company in cooperation with the dentist Carl Sauer and Kurt Schimmelbusch introduced his mask for ether anesthesia. Carl Ludwig Schleich reported at the German congress of surgery in 1894 about his first experience with infiltration anesthesia. Spinal anesthesia developed by August Bier in Kiel was improved during his time in Berlin.

[Otto J"ungling--the first "specialist in anesthesiology" in Berlin]. / Otto Jüngling--der erste "Facharzt für Anaesthesiologie" in Berlin.

Compared to English-speaking countries, anaesthesiology in Germany developed into an independent field relatively late. German doctors were sent abroad to other European countries to learn modern anaesthetic techniques. At the beginning of the fifties, colleagues from East Germany had increasing problems to travel abroad. Otto Jüngling, who specialised in anaesthesiology in Vienna under Otto Mayrhofer, came with a work permit to the small town of Quedlinburg in the Harz mountains in November 1952. One year later, in September 1953, he went to Berlin to set up a new department of anaesthesiology at Friedrichshain Hospital. After recognition of his speciality by the Austrian General Medical Council in Linz, Otto Jüngling became the first specialist for anaesthesiology to practise in Berlin. Scientifically he worked on the development of new anaesthetics and anaesthetic machines. A transportable suction unit was one of his excellent ideas. Furthermore, he rendered outstanding services to the training of anaesthesists in Berlin. Otto Jüngling resigned in February 1959 due to unsatisfactory cooperation with public authorities and went back to Austria were he lives today as a pensioner.

Competitive binding of acetate and chloride in photosystem II.

The binding of chloride and acetate to photosystem II (PSII) was examined to elucidate the mechanism of acetate inhibition. The mode of inhibition was studied, and individual binding sites were assigned by steady-state O2 evolution measurements in correlation with electron paramagnetic resonance (EPR) results. Two binding sites were found for acetate, one chloride-sensitive on the electron donor side and one chloride-insensitive on the electron acceptor side. The respective binding constants were as follows: KCl = 0.5 +/- 0.2 mM (chloride binding to the donor side), KI = 16 +/- 5 mM (acetate binding to the donor side), and KI' = 130 +/- 40 mM (acetate binding to the acceptor side). When acetate was bound to the acceptor side of PSII, 200 K illumination induced a narrowed form of the QA-FeII EPR signal, the yield of which was independent of the chloride concentration. When acetate was bound to the donor side, room-temperature illumination produced the S2YZ* state. EPR measurements showed that both the yield and formation rate of this state increased with acetate concentration. Increasing chloride concentrations slowed the rate of formation of the S2YZ* state, but did not affect the steady-state yield of the S2YZ* state. These findings indicate that the light-induced reactions in acetate-inhibited PSII are modulated by both donor side and acceptor side binding of acetate, while the steady-state yield of the S2YZ* state at the high PSII concentrations used for EPR measurements depends primarily on acceptor side turnover. Our data further support a close proximity of chloride to YZ*, indicating a possible role for chloride in the electron-transfer mechanism at the O2-evolving complex.

Mapping RNA-protein interactions in ribonuclease P from Escherichia coli using electron paramagnetic resonance spectroscopy.

Ribonuclease P (RNase P) is a catalytic ribonucleoprotein (RNP) essential for tRNA biosynthesis. In Escherichia coli, this RNP complex is composed of a catalytic RNA subunit, M1 RNA, and a protein cofactor, C5 protein. Using the sulfhydryl-specific reagent (1-oxyl-2,2,5, 5-tetramethyl-Delta3-pyrroline-3-methyl)methanethiosulfonate (MTSL), we have introduced a nitroxide spin label individually at six genetically engineered cysteine residues (i.e., positions 16, 21, 44, 54, 66, and 106) and the native cysteine residue (i.e., position 113) in C5 protein. The spin label covalently attached to any protein is sensitive to structural changes in its microenvironment. Therefore, we expected that if the spin label introduced at a particular position in C5 protein was present at the RNA-protein interface, the electron paramagnetic resonance (EPR) spectrum of the spin label would be altered upon binding of the spin-labeled C5 protein to M1 RNA. The EPR spectra observed with the various MTSL-modified mutant derivatives of C5 protein indicate that the spin label attached to the protein at positions 16, 44, 54, 66, and 113 is immobilized to varying degrees upon addition of M1 RNA but not in the presence of a catalytically inactive, deletion derivative of M1 RNA. In contrast, the spin label attached to position 21 displays an increased mobility upon binding to M1 RNA. The results from this EPR spectroscopy-based approach together with those from earlier studies identify residues in C5 protein which are proximal to M1 RNA in the RNase P holoenzyme complex.

Characterization of the interaction between manganese and tyrosine Z in acetate-inhibited photosystem II.

When acetate-inhibited photosystem II (PSII) membranes are illuminated at temperatures above 250 K and quickly cooled to 77 K, a 240 G-wide electron paramagnetic resonance (EPR) signal is observed at 10 K. This EPR signal arises from a reciprocal interaction between the spin 1/2 ground state of the S2 state of the Mn4 cluster, for which a multiline EPR signal with shifted 55Mn hyperfine peaks is observed, and the oxidized tyrosine residue, YZ*, for which a broadened YZ* EPR spectrum is observed. The S2YZ* EPR signal in acetate-inhibited PSII is the first in which characteristic spectral features from both paramagnets can be observed. The observation of distinct EPR signals from each of the paramagnets together with the lack of a half-field EPR transition indicates that the exchange and dipolar couplings are weak. Below 20 K, the S2YZ* EPR signal in acetate-inhibited PSII is in the static limit. Above 20 K, the line width narrows dramatically as the broad low-temperature S2YZ* EPR signal is converted to a narrow YZ* EPR signal at room temperature. The line width narrowing is interpreted to be due to averaging of the exchange and dipolar interactions between YZ* and the S2 state of the Mn4 cluster by rapid spin-lattice relaxation of the Mn4 cluster as the temperature is increased. Decay of the S2YZ* intermediate at 200 K shows that the g = 4.1 form of the S2 state is formed and that a noninteracting S2-state multiline EPR signal is not observed as an intermediate in the decay. This result shows that a change in the redox state of YZ induces a spin-state change in the Mn4 cluster in acetate-inhibited PSII. The interconversion between spin states of the Mn4 cluster in acetate-inhibited PSII supports the idea that YZ oxidation or YZ* reduction is communicated to the Mn4 cluster through a direct hydrogen-bonding pathway, possibly involving a ligand bound to the Mn4 cluster.

Hypochlorite-modified low-density lipoprotein stimulates human polymorphonuclear leukocytes for enhanced production of reactive oxygen metabolites, enzyme secretion, and adhesion to endothelial cells.

Hypochlorite-oxidized low-density lipoprotein ((-)OCl-LDL) has been shown to stimulate various functions of human polymorphonuclear leukocytes (PMNLs). Incubation of PMNLs with (-)OCl-LDL (produced by incubation of 0.4 mM LDL cholesterol with 1 mM NaOCl for 40 min at 37 degrees C) but not native or copper-oxidized LDL induced a substantial generation of reactive oxygen species (ROS) as measured by means of chemiluminescence with one peak at 10-12 min. Upon stimulation with (-)OCl-LDL about 70% of ROS (hydrogen peroxide and superoxide anion) were released from the cells into the extracellular environment. The (-)OCl-LDL-induced increase of the respiratory burst was dependent upon the dose, exposure time, and extent of LDL oxidation. Cytochalasin B, an inhibitor of phagocytosis, markedly diminished the LDL-induced ROS generation to nearly 40% of control values. (-)OCl-LDL enhanced the adhesion of PMNLs to human umbilical venous endothelial cells 2.5-fold as compared to native LDL and promoted the secretion of the active granule enzymes lysozyme and beta-glucuronidase. Together, the results suggest a potential role of LDL-activated PMNLs in initiating and/or maintaining the inflammatory process during the early phase of atherosclerotic lesion development. Alternatively, PMNLs may also play a protective role by phagocytosing oxidized LDL and, thus, preventing further detrimental atherogenic effects of oxidized LDL.

[Selenium administration in patients with sepsis syndrome. A prospective randomized study]. / Selensubstitution bei Sepsispatienten. Eine prospektiv randomisierte Studie.

PATIENTS AND METHOD: In this study the effect of antioxidative therapy with sodium selenite was investigated in patients with systemic inflammatory response syndrome (S. I. R. S.) and multiple organ failure. 40 patients were included in this prospective randomized study. The patients were observed over a period of 28 days. The letality rate within 28 days was excepted as main criteria. The Apache-II and the MOF-Score of Goris were used as clinical parameters. 20 patients were treated with sodium selenite over a period of 28 days. RESULT: This antioxidative therapy reduced the letality rate from 40 to 15%.

The risk of pancreaticointestinal anastomosis can be predicted preoperatively.

The risk of developing postoperative complications following pancreatic resection depends mainly on how difficult it is to perform a proper pancreaticointestinal anastomosis. We have evaluated the serum pancreolauryl test, a rapid tubeless pancreatic function test, as a simple preoperative predictor of the degree of pancreatic fibrosis. Degree of fibrosis in turn provides an indirect parameter for the difficulties of performing a proper and safe pancreaticointestinal anastomosis. In 35 patients (21 chronic pancreatitis, 14 pancreatic tumors) undergoing major pancreatic resection, we found a negative correlation (r = -0.75, p < 0.001) between the degree of fibrosis at the resection margin and the serum pancreolauryl test results. Patients with chronic pancreatitis had a significantly higher degree of fibrosis at the resection margin (59 +/- 22 vs. 34 +/- 25%; X +/- SD; p < 0.01) and lower fluorescein serum concentrations (2.6 +/- 1.9 vs. 4.3 +/- 2.1 micrograms/ml; X +/- SD; p < 0.01) in comparison with patients with pancreatic tumors. These findings indicate that the degree of pancreatic fibrosis, the difficulties of performing a proper pancreaticointestinal anastomosis, and subsequently the potential risk of postoperative complications can easily be predicted preoperatively.

Comparisons in good and bad: criminality in Japan and Germany.

In the field of criminological comparison, Japan and Germany are very suitable subjects. A nearly identical penal law and a social structure of highly developed industrial societies after a complete destruction at the end of World War War II give a good match. At first sight, Japan's crime rate is less than 1/4 of that in Germany. The impact of organised crime on the reduction of general crime is discussed.