Strontium isotope characterization of Karoo volcanic rocks

Karoo volcanics of both mafic and felsic composition cover large areas of southern Africa, and are characterized by considerable ranges in their initial 87Sr/86Sr (i.e. Ro) ratios. Mafic volcanics from the eastern and western continental margins show the greatest range in Ro ratios, i.e. Lebombo-Nuanetsi area: 0.7035-0.7134 and Etendeka: 0.7030-0.7135 respectively. In the Central Karoo area the mafic rocks show a smaller spread of ratios: 0.7046-0.7094

Teacher as learner: a personal reflection on a short course for South African university educators

Higher education is understood to play a critical role in ongoing processes of social transformation in post-apartheid South Africa through the production of graduates who are critical and engaged citizens. A key challenge is that institutions of higher education are themselves implicated in reproducing the very hierarchies they hope to transform. In this paper, I reflect critically on my experiences of a course aimed at transforming teaching through transforming teachers. In this paper, I foreground my own positionality as a white female educator as I draw on feminist theorising to reflect on my experiences as a learner in the Community, Self and Identity course. I suggest that we need to teach in ways that are more cognisant of the complexities of the constraints on personal freedom in the past if we are to contribute to the development of social justice in the future.IS

Anti-Neuroinflammatory effects of the extract of Achillea fragrantissima

<p>Abstract</p> <p>Background</p> <p>The neuroinflammatory process plays a central role in the initiation and progression of neurodegenerative diseases such as Parkinson's and Alzheimer's diseases, and involves the activation of brain microglial cells. During the neuroinflammatory process, microglial cells release proinflammatory mediators such as cytokines, matrix metalloproteinases (MMP), Reactive oxygen species (ROS) and nitric oxide (NO). In the present study, extracts from 66 different desert plants were tested for their effect on lipopolysaccharide (LPS) - induced production of NO by primary microglial cells. The extract of <it>Achillea fragrantissima </it>(<it>Af</it>)<it/>, which is a desert plant that has been used for many years in traditional medicine for the treatment of various diseases, was the most efficient extract, and was further studied for additional anti-neuroinflammatory effects in these cells.</p> <p>Methods</p> <p>In the present study, the ethanolic extract prepared from <it>Af </it>was tested for its anti-inflammatory effects on lipopolysaccharide (LPS)-activated primary cultures of brain microglial cells. The levels of the proinflammatory cytokines interleukin1β (IL-1β) and tumor necrosis factor-α (TNFα) secreted by the cells were determined by reverse transcriptase-PCR and Enzyme-linked immunosorbent assay (ELISA), respectively. NO levels secreted by the activate cells were measured using Griess reagent, ROS levels were measured by 2'7'-dichlorofluorescein diacetate (DCF-DA), MMP-9 activity was measured using gel zymography, and the protein levels of the proinflammatory enzymes cyclooxygenase-2 (COX-2) and induced nitric oxide synthase (iNOS) were measured by Western blot analysis. Cell viability was assessed using Lactate dehydrogenase (LDH) activity in the media conditioned by the cells or by the crystal violet cell staining.</p> <p>Results</p> <p>We have found that out of the 66 desert plants tested, the extract of <it>Af </it>was the most efficient extract and inhibited ~70% of the NO produced by the LPS-activated microglial cells, without affecting cell viability. In addition, this extract inhibited the LPS - elicited expression of the proinflammatory mediators IL-1β, TNFα, MMP-9, COX-2 and iNOS in these cells.</p> <p>Conclusions</p> <p>Thus, phytochemicals present in the <it>Af </it>extract could be beneficial in preventing/treating neurodegenerative diseases in which neuroinflammation is part of the pathophysiology.</p

Is there a role for 99mTc-HMPAO leucocyte scintigraphy in infective endocarditis?

Infective endocarditis is an important disease in developing countries. A combination of clinical findings, typical organisms cultured from blood, and specific echocardiographic features are used to establish the diagnosis. The diagnosis is often difficult because cultures are not always positive and transthoracic echocardiography lacks sensitivity and specificity, leading to delayed treatment or inappropriate therapy. As 99mTc-HMPAO-labelled leucocyte scintigraphy is used routinely to evaluate patients with suspected infectious processes, it was postulated that this technique might also aid in the diagnosis of infective endocarditis in patients with underlying chronic rheumatic heart disease or other valvular disease. Six patients were referred for 99mTc-HMPAO-labelled leucocyte scintigraphy. The white blood cells were labelled according to standard procedures. Whole-body planar imaging and single photon emission tomography of the chest area, with imaging at 30 minutes, 3 hours and 24 hours after the administration of the labelled leucocytes, were performed on all patients. All the scintigrams were negative. The reasons for the negative findings are not entirely clear, but probably reflect the pathological nature of vegetations, which consist mainly of masses of fibrin, clotted platelets and blood cell debris, containing the causative organisms. Leucocytes do not play a major role in the pathological process. Although only six patients were studied, it appears that 99mTc-HMPAO leucocyte scintigraphy is of little value in the evaluation of patients with infective endocarditis. A study after the administration of radiolabelled antibiotics may be of greater value and should be considered in these patients.Articl

Infective endocarditis: negative 99mTc-HMPAO leucocyte scintigraphy.

GesondheidswetenskappeInterne GeneeskundePlease help us populate SUNScholar with the post print version of this article. It can be e-mailed to: [email protected]

Major and trace elements and Nd and Sr isotope geochemistry of basalts at DSDP Leg 74 Holes

Basement intersected in Holes 525A, 528, and 527 on the Walvis Ridge consists of submarine basalt flows and pillows with minor intercalated sediments. These holes are situated on the crest and mid- and lower NW flank of a NNW-SSE-trending ridge block which would have closely paralleled the paleo mid-ocean ridge. The basalts were erupted approximately 70 Ma, a date consistent with formation at the paleo mid-ocean ridge. The basalt types vary from aphyric quartz tholeiites on the Ridge crest to highly Plagioclase phyric olivine tholeiites on the flank. These show systematic differences in incompatible trace element and isotopic composition, and many element and isotope ratio pairs form systematic trends with the Ridge crest basalts at one end and the highly phyric Ridge flank basalts at the other. The low 143Nd/144Nd (0.51238) and high 87Sr/86Sr (0.70512) ratios of the Ridge crest basalts suggest derivation from an old Nd/Sm and Rb/Sr enriched mantle source. This isotopic signature is similar to that of alkaline basalts on Tristan da Cunha but offset by somewhat lower 143Nd/144Nd values. The isotopic ratio trends may be extrapolated beyond the Ridge flank basalts (which have 143Nd/144Nd of 0.51270 and 87Sr/86Sr of 0.70417) in the direction of typical MORB compositions. These isotopic correlations are equally consistent with mixing of depleted and enriched end-member melts or partial melting of an inhomogeneous, variably enriched mantle source. However, observed Zr-Ba-Nb-Y interelement relationships are inconsistent with any simple two-component model of magma mixing or partial melting. They also preclude extensive involvement of depleted (N-type) MORB material or its mantle sources in the petrogenesis of Walvis Ridge basalts