Composition controlled spin polarization in Co(1-x)Fe(x)S(2) alloys

The transition metal (TM) chalcogenides of the form TMX(2) (X = S or Se) have been studied for decades due to their interesting electronic and magnetic properties such as metamagnetism and metal-insulator transitions. In particular, the Co(1-x)Fe(x)S(2) alloys were the subject of investigation in the 1970s due to general interest in itinerant ferromagnetism. In recent years (2000-present) it has been shown, both by electronic structure calculations and detailed experimental investigations, that Co(1-x)Fe(x)S(2) is a model system for the investigation of highly spin polarized ferromagnetism. The radically different electronic properties of the two endpoint compounds (CoS(2) is a narrow bandwidth ferromagnetic metal, while FeS(2) is a diamagnetic semiconductor), in a system forming a substitutional solid solution allows for composition control of the Fermi level relative to the spin split bands, and therefore composition-controlled conduction electron spin polarization. In essence, the recent work has shown that the concept of 'band engineering' can be applied to half-metallic ferromagnets and that high spin polarization can be deliberately engineered. Experiments reveal tunability in both sign and magnitude of the spin polarization at the Fermi level, with maximum values obtained to date of 85% at low temperatures. In this paper we review the properties of Co(1-x)Fe(x)S(2) alloys, with an emphasis on properties of relevance to half-metallicity. Crystal structure, electronic structure, synthesis, magnetic properties, transport properties, direct probes of the spin polarization, and measurements of the total density of states at the Fermi level are all discussed. We conclude with a discussion of the factors that influence, or even limit, the spin polarization, along with a discussion of opportunities and problems for future investigation, particularly with regard to fundamental studies of spintronic devices.

Measurement of the 3D Born-Oppenheimer potential of a proton in a hydrogen-bonded system via Deep Inelastic Neutron Scattering: the superprotonic conductor Rb(3)H(SO(4))(2)

We report the first direct measurement of the proton 3-D Born-Oppenheimer potential in any material. The proton potential surfaces in the hydrogen-bonded superprotonic conductor Rb(3)H(SO(4))(2) are extracted from the momentum distribution measured using Deep Inelastic Neutron Scattering (DINS). The potential has a single minimum along the bond direction, which accounts for the absence of the antiferroelectric transition seen in the deuterated material. The measured potential is in qualitative agreement with phenomenological double Morse potentials that have been used to describe hydrogen bonds in other systems.

[Historical aspects of echinococcosis--an ancient but still relevant zoonosis]

The history of echinococcosis in Europe includes a period of over 2000 years. Already in antiquity metacestodes (hydatids) of Echinococcus granulosus, the causative agents of Cystic Echinococcosis (CE), were observed in animals and humans. Alveolar Echinococcosis (AE), caused by metacestodes of E. multilocularis, was identified as a disease entity only in the middle of the 19th century. It took about 100 years until it was undoubtedly clarified and accepted that CE and AE are not caused by a single Echinococcus species, but by E. granulosus and E. multilocularis, respectively. In the 20th century significant progress has been achieved in echinococcosis research, including diagnosis, epidemiology, therapy, immunology, molecular biology and other fields. However, CE and AE remain actual problems as in many endemic regions resources and structures are lacking for effective surveillance and control of these zoonoses threatening humans.

Gesundheitsmonitoring der Migrationsbevölkerung in der Schweiz

With the health monitoring of the Swiss migrant population, a database was created on migrants' health state, their health behaviour and utilization of health services. Thanks to this database, it is now possible to draw representative conclusions on the health status of migrants compared to the indigenous population. Based on the Swiss Health Survey, a questionnaire was developed and translated into several languages. A survey of the foreign population permanently resident in Switzerland as well as of asylum seekers and those temporarily settled in Switzerland was conducted through phone interviews. The interviewees could choose the survey language: in their mother tongue or one of the Swiss languages. A first description of the data is available. The analyses show that the results found for migrants of West European countries are comparable to those of the Swiss population. All other migrants come off worse with regard to health and social indicators. For example, they assess their self-perceived health state more often as "average" or "bad", they feel emotionally less balanced, or visit a doctor more frequently than the Swiss population does. Significant differences can be found within the data of the surveyed migrant population, for example depending on gender, age, residence status or nationality.

Escherichia coli strain Nissle 1917 ameliorates experimental colitis via toll-like receptor 2- and toll-like receptor 4-dependent pathways

Toll-like receptors (TLRs) are key components of the innate immune system that trigger antimicrobial host defense responses. The aim of the present study was to analyze the effects of probiotic Escherichia coli Nissle strain 1917 in experimental colitis induced in TLR-2 and TLR-4 knockout mice. Colitis was induced in wild-type (wt), TLR-2 knockout, and TLR-4 knockout mice via administration of 5% dextran sodium sulfate (DSS). Mice were treated with either 0.9% NaCl or 10(7) E. coli Nissle 1917 twice daily, followed by the determination of disease activity, mucosal damage, and cytokine secretion. wt and TLR-2 knockout mice exposed to DSS developed acute colitis, whereas TLR-4 knockout mice developed significantly less inflammation. In wt mice, but not TLR-2 or TLR-4 knockout mice, E. coli Nissle 1917 ameliorated colitis and decreased proinflammatory cytokine secretion. In TLR-2 knockout mice a selective reduction of gamma interferon secretion was observed after E. coli Nissle 1917 treatment. In TLR-4 knockout mice, cytokine secretion was almost undetectable and not modulated by E. coli Nissle 1917, indicating that TLR-4 knockout mice do not develop colitis similar to the wt mice. Coculture of E. coli Nissle 1917 and human T cells increased TLR-2 and TLR-4 protein expression in T cells and increased NF-kappaB activity via TLR-2 and TLR-4. In conclusion, our data provide evidence that E. coli Nissle 1917 ameliorates experimental induced colitis in mice via TLR-2- and TLR-4-dependent pathways.

Comparison of linkage disequilibrium patterns between the HapMap CEPH samples and a family-based cohort of Northern European descent

The International HapMap Consortium has determined the linkage disequilibrium (LD) patterns of four major human populations. The aim of our investigation was to compare the LD patterns of the HapMap CEPH (Centre d'Etude du Polymorphisme Humain) samples with a family-based cohort of similar ancestry to determine its usefulness as a reference population for disease association studies. We examined four genomic regions on chromosomes 7q, 12p, and 14q totaling 14.3 Mb, initially identified in our linkage study of obesity and the metabolic syndrome. Near identical patterns of LD were detected in both populations. Furthermore, tagSNPs selected based on the HapMap CEPH cohort data capture over 98% of the variants at an r2 > 0.8 in the disease cohort. This confirms the usefulness of the CEPH cohort of the HapMap as a reference sample for further investigations into the genomic variation of populations of Northern European descent.

Toll-like receptor (TLR) polymorphisms in African children: common TLR-4 variants predispose to severe malaria

Genetic host factors play a substantial role in susceptibility to and severity of malaria, which continues to cause at least one million deaths per year. Recently, members of the toll-like receptor (TLR) family have been shown to be involved in recognition of the etiologic organism Plasmodium falciparum: The glycosylphosphatidylinisitol anchor induces signaling in host cells via TLR-2 and -4, while hemozoin-induced immune activation involves TLR-9. Binding of microbial ligands to the respective TLRs triggers the release of pro-inflammatory cytokines via the TLR/IL-1 receptor (TIR) domain and may contribute to the host response, including pro-inflammatory cytokine induction and malarial fever. In a case-control study among 870 Ghanaian children, we examined the influence of TLR-2, -4, and -9 polymorphisms in susceptibility to severe malaria. TLR-2 variants common in Caucasians and Asians were completely absent. However, we found a new, rare mutation (Leu658Pro), which impairs signaling via TLR-2. We failed to detect any polymorphisms within the TLR-9/interleukin-1 receptor domain. Two frequent TLR-9 promoter polymorphisms did not show a clear association with malaria severity. In contrast, the TLR-4-Asp299Gly variant occurred at a high rate of 17.6% in healthy controls, and was even more frequent in severe malaria patients (24.1%, p<0.05). Likewise, TLR-4-Thr399Ile was seen in 2.4% of healthy children and in 6.2% of patients (p=0.02). TLR-4-Asp299Gly and TLR-4-Thr399Ile conferred an 1.5- and 2.6-fold increased risk of severe malaria, respectively. These findings suggest TLR4-mediated responses to malaria in vivo and TLR-4 polymorphisms to be associated with disease manifestation. However some gray areas also suggest the scope for further improvements.

Tularaemia outbreak in hare hunters in the Darmstadt-Dieburg district, Germany

In November 2005, an outbreak of tularaemia occurred among a group of thirty nine hunters and beaters who had participated in a hare hunt on 29 October in the Darmstadt-Griesheim area in the state of Hessen

[Psychiatric aspects of plant poisonings]

Plant poisonings have been reported since ancient times. Despite this, little attention is paid to intoxications with herbal poisons by psychiatric literature and the danger from poisonous plants is commonly underestimated. This problem is discussed here, and advice for the prevention of plant poisonings and generally dealing with patients intoxicated by herbal poisons is given.

Unified tensile fracture criterion

We find that the classical failure criteria, i.e., maximum normal stress criterion, Tresca criterion, Mohr-Coulomb criterion, and von Mises criterion, cannot satisfactorily explain the tensile fracture behavior of the bulk metallic glass (BMG) materials. For a better description, we propose an ellipse criterion as a new failure criterion to unify the four classical criteria above and apply it to exemplarily describe the tensile fracture behavior of BMGs as well as a variety of other materials. It is suggested that each of the classical failure criteria can be unified by the present ellipse criterion depending on the difference of the ratio alpha=tau(0)/sigma(0).

A coding mutation within the first exon of the human MD-2 gene results in decreased lipopolysaccharide-induced signaling

MD-2 is an accessory protein of the Toll-like receptor (TLR)-4, necessary for assembling a receptor complex to sense low quantities of lipopolysaccharide in order to subsequently trigger innate immune responses. MD-2 and TLR-4 are expressed on a variety of immunocompetent cells. Mutations within the TLR-4 gene have been shown to attenuate immune responses against lipopolysaccharide in mice. In humans, a TLR-4 polymorphism has been associated with a higher risk for developing severe Gram-negative sepsis and with a lower risk for atherosclerosis. Since MD-2 is an essential part of the lipopolysaccharide receptor complex, we screened 20 patients that underwent surgical cancer therapy for novel MD-2 mutations by a single-strand conformation polymorphism technique. In one patient we found an A --> G substitution at position 103, resulting in an amino-acid exchange from Thr 35 to Ala. Reporter gene assays revealed that this mutation resulted in a reduced lipopolysaccharide-induced signaling. The patient displayed an uneventful postoperative course, with the exception of slightly decreased TNF-alpha levels after in vitro stimulation with LPS as compared to wt patients. Genotyping of a further 41 patients by a newly developed Lightcycler/FRET method failed to detect any additional polymorphism carriers, indicating that this is a rare mutation.

103 GAP JUNCTIONAL INTERCELLULAR COMMUNICATION IS DISPENSIBLE DURING REGULATION OF TIGHT JUNCTION MEMBRANE ASSEMBLY BY CELL CONTACT PATTERN AND PKC SIGNALING

Contact symmetries are involved in regulating cell lineage segregation during blastocyst biogenesis when tight junction (TJ) membrane assembly is restricted to the epithelial trophectoderm (TE). Manipulation of cell contact patterns by immunosurgical isolation of inner cell masses (ICMs) providing a contact-free cell surface serves as a switch to induce TE differentiation upon in vitro culture. In this model, protein kinase C (PKC)-mediated signaling up-regulates TJ membrane assembly. Whether signaling via gap junctional intercellular communication (GJIC) affects these processes is controversial. The current study investigates the interrelationship between changes in cell contact pattern, PKC signaling, and GJIC on TE differentiation and TJ assembly. Eight-cell embryos flushed from MF1 mice were cultured in T6/BSA to time development to early blastocyst stage (<2 h of cavitation). Laser confocal microscopy (BioRad MRC 600, BioRad Laboratories, Inc., Hertfordshire, UK) after immunostaining with antibodies against PKCδ, θ, λ, or ζ isoforms (Transduction Labs, Oxford, UK or Sigma) or junctional proteins (E-cadherin, ZO-2, Occludin, ZO-1α+, Desmoplakin) combined with ALEXA 488 conjugated secondary antibodies (Cambridge Bioscience, Oxford, UK) was used to determine the distribution of PKCs and junctional proteins in intact blastocysts and fully and partially isolated ICMs after immunosurgery and in vitro culture in DMEM + 10% FCS (Eckert et al. 2004 Reproduction 127, 653). While broad PKC activators (1 μM 12-O-tetradecanoylphorbol-13-acetate or Indolactam; Calbiochem, Nottingham, UK) accelerate membrane assembly of the TJ proteins ZO-2 and ZO-1α+ in fully isolated ICMs this up-regulation was suppressed in intact blastocysts (n = 32–47 per treatment and antibody) and in partially isolated ICMs (remnants of lysed TE remaining surrounding the ICM; n = 17–21 per treatment and antibody) for up to 24 h with no TJ protein detectable within the ICM, even after two consecutive rounds of TE lysis (n = 13–22 per treatment and antibody). When GJIC was inhibited during blastocyst formation in vitro and in cultured fully isolatd ICMs by 18 α-glycyrrhetinic acid (AGA, 65 μM; Sigma), cavitation rate and distribution of PKCs or junction assembly were not affected compared to controls (70–80% cavitated with characteristic distribution of junctional proteins and PKCs; P > 0.05, ANOVA; n = 15–20 per treatment, antibody, and cell contact pattern). When GJIC inhibition by AGA was confirmed by Lucifer yellow (Sigma) injection (no dye transfer in 82–100%, n = 14–17 per contact pattern), GJIC was also absent in 50% of fully isolated ICMs without AGA treatment, suggesting that cell contact modulation may affect GJIC. Taken together, our data suggest that cell contact pattern regulates TJ assembly via PKC signaling pathways and may also affect GJIC. GJIC appeared dispensable during cavitation, TJ assembly, and PKC signaling. A better understanding of the interrelationships between different signaling mechanisms may help to improve embryo culture methods and viability. Funding by the Wellcome Trust and MRC is gratefully acknowledged.

Nanostructured Ti-based multi-component alloys with potential for biomedical applications

A group of Ti(60)Cu(14)Ni(12)Sn(4)M(10) (M=Nb, Ta, Mo) alloys was prepared using arc melting and copper mold casting. The as-prepared alloys have a composite microstructure containing a micrometer-sized dendritic beta-Ti(M) phase dispersed in a nanocrystalline matrix. These new alloys exhibit a low Young's modulus in the range of 59-103 GPa, and a high yield strength of 1037-1755 MPa, together with large plastic strains. The combination of high strength and low elastic modulus offers potential advantages in biomedical applications.

Observations on the Development of Echinococcus multilocularis in Cats

The development of a European isolate of Echinococcus multilocularis was compared in cats and dogs at the end of the prepatent period. Echinococcus multilocularis established in all dogs and cats, but worm recovery was significantly greater from dogs than from cats. Overall, worms in cats were not as advanced as those in dogs in terms of development and maturation, but there was no evidence of retarded development or stunted forms. These results confirm that dogs are highly susceptible to E. multilocularis, whereas cats have lower and more variable recovery rates. However, because cats produce thick-shelled eggs of E. multilocularis after experimental and natural infections, they have to be regarded as potential sources of infection both for intermediate and accidental hosts, including humans. However, their general role in the epidemiology of the infection has yet to be determined.

Analysis of polymorphic microsatellites within the bovine and ovine prion protein (PRNP) genes

Twenty-four microsatellite sites with at least three repeats were found in the bovine prion protein gene (PRNP) and 23 in the ovine PRNP gene. Eight microsatellite sites were polymorphic in cattle and six in sheep with up to 10 alleles per site. In many cases allelic DNA fragments had variants in microsatellite sites and in flanking regions. Distances between microsatellite sites in eight genes from cattle and sheep occurred on average every 0.9 kb. The numerous polymorphic microsatellite sites will improve analysis of phylogenetic origin of different PRNP alleles and trait association studies for bovine spongiform encephalopathy (BSE) and scrapie.

Fracture mechanisms in bulk metallic glassy materials

We find that the failure of bulk metallic glassy (BMG) materials follows three modes, i.e., shear fracture with a fracture plane significantly deviating from 45 degrees to the loading direction, normal tensile fracture with a fracture plane perpendicular to the loading direction, or distensile fracture in a break or splitting mode with a fracture plane parallel to the loading direction. The actually occurring type of failure strongly depends on the applied loading mode and the microstructure of the material. Extensive evidence indicates that the Tresca fracture criterion is invalid, and for the first time, three fracture criteria are developed for isotropic materials with high strength, such as advanced BMGs or the newly developed bulk nanostructural materials.

Predictive values and quality control of techniques for the diagnosis of Echinococcus multilocularis in definitive hosts

By the end of the 1980s the only reliable technique for diagnosing the intestinal Echinococcus multilocularis infection of definitive hosts was parasite detection at necropsy. Currently, several techniques for the post mortem and in vivo diagnosis are available, including classical and modern methods. The sedimentation and counting technique (SCT) is used for the exact determination of the worm burden in the intestine after necropsy. The SCT has high sensitivity and specificity values (both close to 100%) and can be regarded as 'gold standard'. The principle of the intestinal scraping technique (IST) is the stereomicroscopic examination of at least 15 intestinal thick smears. This technique has a sensitivity of 78% and a specificity approximating 100%. In recent years, the IST has been successfully used in large post mortem surveys of foxes for E. multilocularis. The newer techniques for detecting coproantigens by ELISA (CA-ELISA) exhibit rather high sensitivities between 84 and 95%, combined with very high specificities of >96%, the latter regarding non-Echinococcus cestodes and other parasites. However, cross-reactivity may occur with E. granulosus. Copro-DNA detection by PCR is also highly sensitive (89-94%) and specific (100%). With the SCT, IST and Copro-PCR one person can only examine about 10-20 animals per day, whereas the CA-ELISA allows the examination of 200 samples. Therefore, the latter test is suited for mass-screening of definitive host populations. Both the CA-ELISA and the Copro-PCR allow the examination of materials from dead and living animals, including faecal samples collected in the field. Quite often diagnostic techniques have been used without adequate quality control and proper definition of their performance characteristics, including diagnostic sensitivity, specificity, predictive values and some other parameters. Examples are presented with the aim to demonstrate the need and the value of calculating the predictive values for assays used to diagnose the E. multilocularis infection in individual animals and in definitive host populations.

Various approaches of teaching veterinary parasitology

In this paper, we discuss the advantages and disadvantages of various approaches of teaching veterinary parasitology, including the disciplinary, the problem-oriented and combined approaches. In the disciplinary approach, parasitology is taught in the classical manner as a coherent subject, covering parasite morphology, biology, molecular biology, epidemiology, pathology, immunology, clinical manifestation, diagnosis, therapy, control, and prevention. Problem-oriented teaching approaches the subjects starting from diseases in animal species or from organ systems or other objectives (e.g. food safety); it also tackles training of skills for problem solving and self-learning. Combined approaches include elements of the disciplinary approach and those of other methods. A combined approach of teaching veterinary parasitology, including basic disciplinary teaching of at least 70-90 h, and additional problem-oriented education, was recently proposed in a resolution by the World Association for the Advancement of Veterinary Parasitology [WAAVP News Lett. 5 (1) 3-4]. In 1999, a new curriculum has been established at the Faculty of Veterinary Medicine, University of Berne, originally planned as a combination of organ-focused and problem-based approach. This model was soon identified to cause problems in teaching some disciplines, including infectious diseases. Conversely, the short-term experiences with this combined approach also confirmed some advantages of problem-oriented teaching in other, mainly clinical domains. Nevertheless, closer interdisciplinary contact and collaboration--especially in elective teaching--was enforced between paraclinical and clinical teaching by reforming the curriculum. However, it turned out that large student numbers in relation to the resources of manpower, rooms and finances limited the workability of the curriculum. Therefore, further and probably continuous improvement of the curriculum is necessary.

Teaching of undergraduate veterinary parasitology in some European countries

A review revealed that at 20 veterinary faculties in European countries parasitology is represented in the curriculum of veterinary medicine with an average of 105 core contact hours, devoted to lectures (58%) and practicals (42%). However, there is a high diversity between faculties with ranges of total contact hours between 48 and 156. Three faculties are close to the minimum of 70 core contact hours recommended by WAAVP (2002), and one faculty is below this limit. In one of the faculties parasitology is completely integrated into interdisciplinary teaching activities, in some others there are developments in this direction which include the risk of dissolving parasitology as a discipline. One faculty with a high degree of integrated teaching has already abolished the parasitological examination. Parasitology is preferentially taught in the years three, four and five of the curriculum, but there is great variation between the faculties. Most teachers in the faculties are veterinarians. In many faculties the large numbers of students and the unsatisfactory academic teaching staff:student ratio represent a significant problem. This problem may increase with more teaching obligations caused by new curricula. Due to the high diversity in content and structure of teaching curricula of veterinary medicine between veterinary faculties in Europe international and even national exchange of students is inhibited. Therefore, and for many other reasons more activities should be initiated towards harmonisation of the study curricula in Europe.