Progress in Neutron Scattering Studies of Spin Excitations in High-Tc Cuprates

Neutron scattering experiments continue to improve our knowledge of spin fluctuations in layered cuprates, excitations that are symptomatic of the electronic correlations underlying high-temperature superconductivity. Time-of-flight spectrometers, together with new and varied single crystal samples, have provided a more complete characterization of the magnetic energy spectrum and its variation with carrier concentration. While the spin excitations appear anomalous in comparison with simple model systems, there is clear consistency among a variety of cuprate families. Focusing initially on hole-doped systems, we review the nature of the magnetic spectrum, and variations in magnetic spectral weight with doping. We consider connections with the phenomena of charge and spin stripe order, and the potential generality of such correlations as suggested by studies of magnetic-field and impurity induced order. We contrast the behavior of the hole-doped systems with the trends found in the electron-doped superconductors. Returning to hole-doped cuprates, studies of translation-symmetry-preserving magnetic order are discussed, along with efforts to explore new systems. We conclude with a discussion of future challenges.Comment: revised version, to be published in JPSJ, 20 pages, 21 figure

Faecal calprotectin concentrations in apparently healthy children aged 0-12 years in urban Kampala, Uganda: a community-based survey

<p>Abstract</p> <p>Background</p> <p>Calprotectin is a calcium and zinc binding protein, abundant in neutrophils and is extremely stable in faeces. Faecal calprotectin is used as a non-specific marker for gastrointestinal inflammation. It has a good diagnostic precision to distinguish between irritable bowel syndrome and inflammatory bowel disease. Studies have established normal concentrations in healthy children; all these studies have been performed in high-income countries. The objective of this study was to determine the concentration of faecal calprotectin in apparently healthy children aged 0-12 years in urban Kampala, Uganda.</p> <p>Method</p> <p>We tested 302 apparently healthy children aged, age 0-12 years (162 female, 140 male) in urban Kampala, Uganda. The children were recruited consecutively by door-to-door visits. Faecal calprotectin was analyzed using a quantitative enzyme-linked immunosorbent assay. Faeces were also tested for <it>Helicobacter pylori (H. pylori) </it>antigen, for growth of enteropathogens and microscopy was performed to assess protozoa and helminths. A short standardized interview with socio-demographic information and medical history was obtained to assess health status of the children.</p> <p>Results</p> <p>In the different age groups the median faecal calprotectin concentrations were 249 mg/kg in 0 < 1 year (n = 54), 75 mg/kg in 1 < 4 years (n = 89) and 28 mg/kg in 4 < 12 years (n = 159). There was no significant difference in faecal calprotectin concentrations and education of female caretaker, wealth index, gender, habits of using mosquito nets, being colonized with <it>H. pylori </it>or having other pathogens in the stool.</p> <p>Conclusion</p> <p>Concentrations of faecal calprotectin among healthy children, living in urban Ugandan, a low-income country, are comparable to those in healthy children living in high-income countries. In children older than 4 years, the faecal calprotectin concentration is low. In healthy infants faecal calprotectin is high. The suggested cut-off concentrations in the literature can be used in apparently healthy Ugandan children. This finding also shows that healthy children living under poor circumstances do not have a constant inflammation in the gut. We see an opportunity to use this relatively inexpensive test for further understanding and investigations of gut inflammation in children living in low-income countries.</p

Amodiaquine-Associated Adverse Effects After Inadvertent Overdose and After a Standard Therapeutic Dose

A case of an acute dystonic reaction in a child presumptively treated for malaria with amodiaquine, and a case of persistent asymptomatic bradycardia in another child with mild pulmonary stenosis treated with a standard dose of amodiaquine for parasitologically confirmed uncomplicated malaria, is reported. Both subjects were homozygous for the wild type allele of cytochrome P450 2C8, the main enzyme responsible for amodiaquine metabolism. In both subjects, plasma concentrations of N-desethylamodiaquine and N-bis-desethylamodiaquine, the main metabolites of amodiaquine, were normal. No other drugs were detectable in the plasma of these two subjects after further toxicological screening. These observations, which suggest altered metabolism in the subject with an acute dystonic reaction, support the assertion that amodiaquine-associated dystonia is an idiosyncratic reaction. However, the occurrence of bradycardia after a standard dose of amodiaquine, which coincided with the time of expected peak concentrations of the active metabolite of amodiaquine, suggests a direct drug effect. These less reported adverse effects are likely to increase in parallel with the increased use of amodiaquine as a partner drug for combination therapy of malaria in Ghana. Further studies aimed at elucidating the mechanisms underlying these effects are, therefore, required