A.J. van Rensburg

Evaluation of samarium-153 and holmium-166-EDTMP in the normal baboon model

Bone-seeking radiopharmaceuticals such as ethylenediaminetetramethylene phosphonate (EDTMP) complexes of samarium-153 and holmium-166 are receiving considerable attention for therapeutic treatment of bone metastases. In this study, using the baboon experimental model, multicompartmental analysis revealed that with regard to pharmacokinetics, biodistribution, and skeletal localisation, 166Ho-EDTMP was significantly inferior to 153Sm-EDTMP and 99mTc-MDP. A more suitable 166Ho-bone-seeking agent should thus be sought for closer similarity to 153Sm-EDTMP to exploit fully the therapeutic potential of its shorter half-life and more energetic beta radiation.

Three component flow injection analysis with on-line dialysis. Simultaneous determination of free calcium, total calcium and total chloride in milk by flow injection analysis and on-line dialysis

SummaryA fast and reliable fully automated three-component flow injection procedure for the simultaneous determination of free calcium, total calcium and total chloride in milk is described where the three components from a single sample injection (30 μl milk samples) are determined at a sampling rate of 60 samples per hour. The samples are directed to three different channels by using two dialysers in series. Interferences in the determination of free calcium are eliminated by using a dialyser (first in the series) which also separates the total and free calcium. Free calcium is determined by UV/VIS spectrophotometry at 580 nm and total calcium by atomic absorption spectrometry (AAS) at 422.7 nm. Interferences from phosphates in milk in the determination of total calcium by AAS are overcome by using a nitrous oxide-acetylene flame with the necessary suppression with potassium ions. A second dialyser in series is used to eliminate interferences, especially the interference of casein, before the dialysed chloride is measured with a coated tubular chloride-selective electrode. The results obtained for the free calcium, total calcium and total chloride in milk at a sampling rate of 60 samples per hour compared well with data obtained by standard methods. With 30 μl samples the relative standard deviation for milk samples having different concentrations of free calcium (110–170 mg/l free calcium), total calcium (1000–1500 mg/l total calcium) and total chloride (1000–1800 mg/l total chloride) were better than 0.37, 1.01 and 0.25, respectively.

Properties of Proteus mirabilis and Providence Spheroplasts

SUMMARY: Proteus mirabilis strain 13 and Providence strain nctc9211 were converted to osmotically sensitive spheroplasts by growth in the presence of penicillin or glycine in sucrose-supplemented or unsupplemented medium. Lysozyme in the presence of tris and ethylenediaminetetra-acetic acid (EDTA) converted both these strains to spheroplasts. Penicillin spheroplasts could be stabilized with sucrose, streptomycin, spermine or di-valent cations. Electron micrographs of these spheroplasts demonstrated that the outer layer of the bacterial cell wall was retained. Penicillin-induced spheroplasts possessed receptor sites for bacteriophages.

Genetic Transformation in Proteus mirabilis

SUMMARY: A method is described for the isolation of biologically active DNA from Proteus mirabilis strain 13 which could transform auxotrophic mutants of P. mirabilis to prototrophy. This DNA preparation did not transform similar mutants of P. vulgaris. Optimal conditions for transformation were pH 8·5 to 9·5 for the lysate during DNA extraction, DNA concentration of 16 μg./ml. and growth of recipient cells for 5 h. before exposure to DNA.

Erroneous decay corrections in radiotherapy: a Year 2000 safety problem

To determine the potential impact of this problem on the radiotherapy department at Pretoria Academic Hospital, we investigated the computers and computer programs used for the purpose of radioactive decay corrections. The results are disconcerting. A list of all the computers and programs used to calculate any form of decay correction was drawn up. The ability of the operating systems and hrrdware to handle times beyond 2000 were subsequently assessed. On the systems which could fundamentally handle the new century the date was changed manually to 2000 and later. The programs were then executed and the answers vetted manually. Where problems were identified a strategy was drawn up to overcome the problem.