Browsing by Author "Pillay, K"

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    Ageing of chromium(III)-bearing slag and its relation to the atmospheric oxidation of solid chromium(III)-oxide in the presence of calcium oxide
    (Elsevier, 2003) Pillay, K; von Blottnitz, H B; Petersen, J
    Slag arising in ferrochromium and stainless steel production is known to contain residual levels of trivalent chromium. As the chromium is normally bound in the slag matrix in various silicate or spinel phases, and hence not easily mobilised, utilisation or controlled disposal of such slag is generally considered unproblematic. Experimental test work with a number of slag materials indicates, however, that very gradual oxidation of trivalent to hexavalent chromium does occur when the slag is exposed to atmospheric oxygen, rendering a quantifiable but small portion of chromium in this much more mobile and toxic form. Mechanisms and rates of the oxidation reaction were investigated in a number of long-term studies using both original slag materials and artificial mixes of chromium and calcium oxides. Powders of these materials, some of them rolled into balls, were left to age under different conditions for periods of up to 12 months. In the slag samples, which contained between 1 and 3 wt.% chromium, 1000–10 000 μg Cr(VI) were found per gram of chromium within 6–9 months of exposure to an ambient atmosphere. The rate of the oxidation reaction decreased exponentially, and the reaction could generally be said to have ceased within 12 months. In mixtures of calcium and chromium oxides the oxidation reaction is presumed to occur at the boundaries between chromium oxide and calcium oxide phases through diffusion of oxygen along the grain boundaries and of Cr3+ across the boundaries, resulting in the formation of calcium chromate. In the slags, where calcium and chromium oxide can form a solid solution, the oxidation is likely to occur at the exposed surface of grains containing this solution.
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    Atypical teratoid/rhabdoid tumour in a supratentorial location: a report of two cases
    (Health and Medical Publishing Group, 2014) Mahomed, N; Naidoo, J; Dlangamandla, S; Andronikou, S; Pather, S; Pillay, K
    Atypical teratoid/rhabdoid tumour of the central nervous system is a rare, highly aggressive childhood malignancy. The age of presentation is usually <2 years, but this tumour may occur in other age groups. The typical location is the posterior fossa, with supratentorial origin less common. We present two cases of atypical teratoid/rhabdoid tumours, with the suprasellar location of one case proving to be a diagnostic radiological challenge.
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    Clinical-pathological characterisation of children with B-cell non-Hodgkin lymphoma over a ten year period at a tertiary centre in Cape Town
    (2020) Kriel, Magdalena; Phillips, Lee-Ann; Davidson, Alan; Pillay, K; Hendricks, M
    Background: We characterized B-cell non-Hodgkin lymphoma (NHL) cases over ten years at a tertiary children's hospital to contribute to the body of knowledge on pediatric lymphoma in developing countries with a high human immunodeficiency virus (HIV) burden. Methods: A retrospective cohort study using clinical and laboratory records of children newly diagnosed with B-cell NHL from January 2005 to December 2014. Results: Seventy-five children ≤ 15 years were included. The majority had Burkitt lymphoma (n = 61). Twenty-five percent (n = 19) were HIV positive and 16% (n = 12) had concurrent active tuberculosis. Bulky disease was present in 65.7% (n = 46) and 30.1% (n = 22) were classified as Lymphomes Malins B (LMB) risk group C. The five year survival estimates for HIV-negative and HIV-positive children were similar in our cohort: 81% vs. 79% for eventfree survival and 85% vs. 83.9% for overall survival. Of three children with Burkitt lymphoma, HIV and LMB group C, two died within one year. Conclusions: Irrespective of HIV status, the survival of children in our B-cell NHL cohort compares favorably with cure rates in developed nations, although advanced disease remains associated with a poor prognosis. Characterization of childhood NHL cases contributes to accurate risk stratification and tailored treatment.
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    Large cell lymphoma : correlation of HIV status and prognosis with differentiation profiles assessed by immunophenotyping
    (2011) Pather, Sugeshnee; Pillay, K
    The study aimed to contribute a South African perspective by correlating the HIV status and prognosis of DLBCL and PBL with differentiation profiles assessed by immunophenotyping.