Symmetric and antisymmetric exchange anisotropies in quasi-one-dimensional CuSe2_2O5_5 as revealed by ESR

We present an electron spin resonance (ESR) study of single-crystalline spin chain-system CuSe$_2$O$_5$ in the frequency range between 9 GHz and 450 GHz. In a wide temperature range above the N\'{e}el temperature $T_N=17$ K we observe strong and anisotropic frequency dependence of a resonance linewidth. Although sizeable interchain interaction $J_{IC}\approx 0.1 J$ ($J$ is the intrachain interaction) is present in this system, the ESR results agree well with the Oshikawa-Affleck theory for one-dimensional $S=1/2$ Heisenberg antiferromagnet. This theory is used to extract the anisotropies present in CuSe$_2$O$_5$. We find that the symmetric anisotropic exchange $J_c=(0.04 \pm 0.01) \:J$ and the antisymmetric Dzyaloshinskii-Moriya (DM) interaction $D=(0.05\pm 0.01)\:J$ are very similar in size in this system. Staggered-field susceptibility induced by the presence of the DM interaction is witnessed in the macroscopic susceptibility anisotropy.Comment: 8 pages, 7 figures, 2 tables, published in Phys. Rev.

Two-electronic component behavior in the multiband FeSe0.42_{0.42}Te0.58_{0.58} superconductor

We report X-band EPR and $^{125}$Te and $^{77}$Se NMR measurements on single-crystalline superconducting FeSe$_{0.42}$Te$_{0.58}$ ($T_c$ = 11.5(1) K). The data provide evidence for the coexistence of intrinsic localized and itinerant electronic states. In the normal state, localized moments couple to itinerant electrons in the Fe(Se,Te) layers and affect the local spin susceptibility and spin fluctuations. Below $T_c$, spin fluctuations become rapidly suppressed and an unconventional superconducting state emerges in which $1/T_1$ is reduced at a much faster rate than expected for conventional $s$- or $s_\pm$-wave symmetry. We suggest that the localized states arise from the strong electronic correlations within one of the Fe-derived bands. The multiband electronic structure together with the electronic correlations thus determine the normal and superconducting states of the FeSe$_{1-x}$Te$_x$ family, which appears much closer to other high-$T_c$ superconductors than previously anticipated.Comment: 5 pages, 4 figure

Antiferromagnetic fluctuations in the normal state of LiFeAs

We present a detailed study of 75As NMR Knight shift and spin-lattice relaxation rate in the normal state of stoichiometric polycrystalline LiFeAs. Our analysis of the Korringa relation suggests that LiFeAs exhibits strong antiferromagnetic fluctuations, if transferred hyperfine coupling is a dominant interaction between 75As nuclei and Fe electronic spins, whereas for an on-site hyperfine coupling scenario, these are weaker, but still present to account for our experimental observations. Density-functional calculations of electric field gradient correctly reproduce the experimental values for both 75As and 7Li sites.Comment: 5 pages, 3 figures, thoroughly revised version with refined experimental data, accepted for publication as a Rapid Communication in Physical Review B

Milking Characteristics of Istrian and Littoral Dinaric Donkey Breeds

Istrian and Littoral Dinaric donkey are autochthonous breeds which habitat primarily in the Mediterranean part of Croatia. During the second half of the 20th century they have lost primary function as working animals, which led to breeds suppression. Nowadays these two breeds are in the status of endangered ones. One of the possibilities for their economic re-affirmation is launching the program for production and processing donkey’s milk. The aim of the study was to determine the possibility of milk production of Istrian and Littoral Dinaric jennies in terms of quantity and chemical composition. Istrian jennies produce 745.4 mL/milking while Littoral Dinaric produce 317.8 mL/milking. Milk form Littoral Dinaric jennies contained a significantly higher proportion of milk fat and proteins. There were no significant differences in the content of lactose, dry matter, number of somatic cells and microorganisms in milk between these two breeds. Considering the potential for milk production and milk quality, we believe that both breeds are suitable for integration in the programs for milk production, thus enabling for both population to be economically sustainable. It is necessary to develop production technology and markets, with special emphasis considering quality of donkey milk and safety of consumers

A new model for the pathophysiology of Alzheimer's disease: Aluminium toxicity is exacerbated by hydrogen peroxide and attenuated by an amyloid protein fragment and melatonin

Objectives. Although Alzheimer's disease (AD) is the leading cause of dementia in developed countries, there is an as yet unexplained lower prevalence of the disease in parts of Africa. AD is characterised by a catastrophic loss of neurons; free radicals (oxidative toxins) have been implicated in the destruction of the cells through the process of lipid peroxidative damage of cell membranes. Previously aluminium (Al) and a fragment of beta amyloid (Aβ 25 - 35) were shown to exacerbate tree-radical damage, while melatonin reduced this effect. The aim of the present study was: (i) to investigate the conditions detennining the toxicity of Al and Aβ 25 - 35; and (ii) to assess whether melatonin could attenuate the damage done by both aluminium and the amyloid fragment, thus suggesting a pathway for the aetiology of AD.Design. An in vitro model system was used in which free radicals were generated, causing lipid peroxidation of platelet membranes, thus simulating the disease process found in the brain.Results. 1. Al and Aβ 25 - 35 caused lipid peroxidation in the presence of the iron (II) ion (Fe2+, Al being more toxic than Aβ 25 - 35. 2. Aβ 25 - 35 attenuated the lipid peroxidation promoted by Al. 3. Hydrogen peroxide (H2O2 greatly exacerbated the toxicity of Al and Aβ 25 - 35. 4. Melatonin prevented lipid peroxidation by Al and Aβ 25 - 35 in the absence of H2O2, but only reduced the process when H2O2 was present.Conclusions. In the light of the results obtained from the present study, the following hypotheses are formulated. 1. In AD, excessive quantities of Al are taken up into the  brain, where the Al exacerbates iron-induced lipid peroxidatian in the Iysosomes. 2. In response, the normal synthetic pathway of amyloid protein is altered to produce Aβ fragments which attenuate the toxicity of Al. In the process of sequestering the Al and iron, immature plaques are formed in the brain. 3. Microglia are activated, in an attempt to destroy the plaques by secreting reactive oxygen species such as H2O2. At this point in the disease process, lipid peroxidation causes a catastrophic loss of brain cells. 4. Melatonin, together with other free radical scavengers in the brain, reduces the free-radical damage caused by Al and Aβ, except in the latter stages of the disease process. Since melatonin is produced by the pineal gland only in the dark, the excess of electric light in developed countries may help explain why AD is more prevalent in these countries than in rural Africa

Angiotensin II causes b-cell dysfunction through an ER stress-induced proinflammatory response

The metabolic syndrome is associated with an increase in the activation of the renin angiotensin system, whose inhibition reduces the incidence of new-onset diabetes. Importantly, angiotensin II (AngII), independently of its vasoconstrictor action, causes b-cell inflammation and dysfunction, which may be an early step in the development of type 2 diabetes. The aim of this study was to determine how AngII causes b-cell dysfunction. Islets of Langerhans were isolated from C57BL/6J mice that had been infused with AngII in the presence or absence of taurineconjugated ursodeoxycholic acid (TUDCA) and effects on endoplasmic reticulum (ER) stress, inflammation, and b-cell function determined. The mechanism of action of AngII was further investigated using isolated murine islets and clonal b cells. We show that AngII triggers ER stress, an increase in the messenger RNA expression of proinflammatory cytokines, and promotes b-cell dysfunction in murine islets of Langerhans both in vivo and ex vivo. These effects were significantly attenuated by TUDCA, an inhibitor of ER stress. We also show that AngII-induced ER stress is required for the increased expression of proinflammatory cytokines and is caused by reactive oxygen species and IP3 receptor activation. These data reveal that the induction of ER stress is critical for AngII-induced b-cell dysfunction and indicates how therapies that promote ER homeostasis may be beneficial in the prevention of type 2 diabetes. © 2017 Endocrine Society

Alzheimer\u27s disease and vascular dementia in developing countries: prevalence, management, and risk factors

Despite mortality due to communicable diseases, poverty, and human conflicts, dementia incidence is destined to increase in the developing world in tandem with the ageing population. Current data from developing countries suggest that age-adjusted dementia prevalence estimates in 65 year olds are high (≥5%) in certain Asian and Latin American countries, but consistently low (1–3%) in India and sub-Saharan Africa; Alzheimer\u27s disease accounts for 60% whereas vascular dementia accounts for ∼30% of the prevalence. Early-onset familial forms of dementia with single-gene defects occur in Latin America, Asia, and Africa. Illiteracy remains a risk factor for dementia. The APOE ε4 allele does not influence dementia progression in sub-Saharan Africans. Vascular factors, such as hypertension and type 2 diabetes, are likely to increase the burden of dementia. Use of traditional diets and medicinal plant extracts might aid prevention and treatment. Dementia costs in developing countries are estimated to be US$73 billion yearly, but care demands social protection, which seems scarce in these regions

ES-Cell Derived Hematopoietic Cells Induce Transplantation Tolerance

Background: Bone marrow cells induce stable mixed chimerism under appropriate conditioning of the host, mediating the induction of transplantation tolerance. However, their strong immunogenicity precludes routine use in clinical transplantation due to the need for harsh preconditioning and the requirement for toxic immunosuppression to prevent rejection and graft-versus-host disease. Alternatively, embryonic stem (ES) cells have emerged as a potential source of less immunogenic hematopoietic progenitor cells (HPCs). Up till now, however, it has been difficult to generate stable hematopoietic cells from ES cells. Methodology/Principal Findings: Here, we derived CD45 + HPCs from HOXB4-transduced ES cells and showed that they poorly express MHC antigens. This property allowed their long-term engraftment in sublethally irradiated recipients across MHC barriers without the need for immunosuppressive agents. Although donor cells declined in peripheral blood over 2 months, low level chimerism was maintained in the bone marrow of these mice over 100 days. More importantly, chimeric animals were protected from rejection of donor-type cardiac allografts. Conclusions: Our data show, for the first time, the efficacy of ES-derived CD45 + HPCs to engraft in allogenic recipient

The South African Society of Psychiatrists (SASOP) treatment guidelines for psychiatric disorders

The South African Society of Psychiatrists (SASOP) Treatment Guidelines for Psychiatric Disorders have been developed in order to address the local need for guidelines in our unique clinical setting. The need for treatment guidelines has frequently been expressed by South African psychiatrists and other medical practitioners, as well as by other role players such as medical scheme and other funding body advisors and the pharmaceutical industry. While several well-developed international treatment guidelines are readily accessible and are indeed extensively utilised in South Africa, they are not always applicable to our own circumstances. There are often important differences, not only regarding the availability of various psychotropic medications, but also in healthcare settings and availability of resources that need to be considered when selecting particular medications. For example, prescribing compounds that require regular monitoring such as lithium and clozapine may not always be feasible in certain rural settings in South Africa.http://www.sajp.org.za/index.php/sajpam201