A mannitol-salt medium supplemented with 0.002% tellurite (MSOT) supported the growth of 104 of 109 strains of methicillin-resistant Staphylococcus aureus (MRSA) while suppressing 74 of 102 strains of mannitol-positive, methicillin-resistant coagulase-negative staphylococci. MSOT was equally or more sensitive and more differential than a similar formulation without tellurite for the isolation of MRSA from the skin and nares of hospitalized patients. Only S. haemolyticus produced dark gray-to-black colonies on MSOT similar to those of MRSA. MSOT is a useful adjunct to other nonselective culture formulations for the isolation of MRSA from contaminated sources.

Axilla↗

PubMedDate not supplied

Establishing equivalence for activity standards of short-lived radionuclides using the NPL secondary standard radionuclide calibrator.

Conventional comparison techniques used between National Metrology Institutes are not practicable for short-lived radionuclides because of geographical separations and transport difficulties. The NPL Secondary Standard Radionuclide Calibrator provides an alternative approach and a comparison was conducted with 18F to investigate its feasibility. The exercise was successful and the paper details the protocol used, the quality assurance mechanisms introduced to underpin the comparison and an analysis of the results. It was also demonstrated that this approach could be linked to the BIPM SIR system. Recommendations are presented for the extension of this work to other suitable, short-lived radionuclides.

Calibration↗

PubMedDate not supplied

Secondary standardisation of 95mTc.

The radionuclide 95mTc, which has a half-life of 61(2)days and emits a number of gamma-rays, may be used in radiochemical analysis as a yield tracer for the long-lived fission product 99Tc. In this work, we present (i) the production of 95mTc via an (alpha, 2n) reaction with stable 93Nb (a method which does not result in the production of any 97mTc, 98Tc or 99Tc), (ii) the chemical separation of 95mTc from niobium via coprecipitation, liquid-liquid extraction and liquid chromatography, and (iii) the secondary standardisation of 95mTc with high-resolution gamma-ray spectrometry and an ionisation chamber system.

Isotope Labeling↗

PubMedDate not supplied

Calibration of the NPL secondary standard radionuclide calibrator for 125I seeds used for prostate brachytherapy. National Physical Laboratory.

In the therapeutic use of radionuclides, by far the most rapid growth in recent years is that of 125I seeds used for the treatment of prostate cancer. Large numbers of these seeds are used in each treatment and there is a need for a simple but accurate means of confirming their dose rates. This mechanism requires a transfer device for which the calibration factors are traceable to national standards. The NPL secondary standard radionuclide calibrator, because of its guaranteed reproducibility and traceable calibration procedure, is ideally suited for this purpose. A series of characterisation measurements have been performed on the NPL radionuclide calibrator in order to estimate the uncertainty levels that can be achieved and these are presented together with the relevant calibration factors for some typical seeds.

Brachytherapy↗

PubMedDate not supplied

NPL secondary standard radionuclide calibrator. Syringe calibration factors for radionuclides used in nuclear medicine. National Physical Laboratory.

The measurement of the activity of a radiopharmaceutical administration to a patient is normally achieved via the use of a radionuclide calibrator. Although these radionuclides are normally measured initially in a standard glass vial, an aliquot of the solution is then usually withdrawn into a syringe prior to the administration. Both for general quality assurance good practice and for additional guarantees for patient safety, a confirmatory measurement of the syringe is almost obligatory Because of the different geometries and elemental compositions between plastic syringes and glass vials, the calibration factors for syringes may well be significantly different from those for the glass containers. The magnitude of these differences depends on the energies of the emitted photons. A variety of syringes typically used in hospital administrations, and covering a range of volumes and manufacturers, were obtained. The results obtained were compared to those for glass vials and show the large errors that can be produced by ignoring these differences in container format.

Glass↗

PubMedDate not supplied

The Women's Health Trial as an investment.

The Women's Health Trial (WHT), a large, multi-unit randomized controlled trial, would have cost a total of $130 million to test the hypothesis that a 50% reduction in the percentage of calories from dietary fat would yield a detectable reduction in breast cancer incidence. However, the WHT was discontinued because evidence to support the hypothesized relationship between dietary fat and breast cancer was judged insufficient to justify the trial. The analysis presented here was undertaken in order to contribute an economic perspective on this issue. Principles of decision analysis and cost-effectiveness analysis are employed to obtain a preliminary estimate of the expected cost per year of life saved of the WHT, as a function of the prior probability that the hypothesis is true (PRIOR). Under specified basecase assumptions, the estimated expected costs per year of life saved range from $11,900 when PRIOR is assumed to be 0.9 to $25,615 when PRIOR is assumed to be 0.1. Sensitivity analyses suggest that the results are most sensitive to assumptions about the strength of the relationship between dietary fat and breast cancer risk, and that improved when it is assumed that dietary change can be achieved by an inexpensive intervention. The expected cost-effectiveness of the WHT is well within the range of estimates of cost-effectiveness of other disease prevention interventions.

Breast Neoplasms↗

PubMedDate not supplied