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B Oldroyd

Publications and source records attributed to B Oldroyd.

48 records · Page 3Linked to original sources
PubMed1983

Multi-element analysis of the human body using neutron activation.

The calibration described is of the Leeds in vivo neutron activation facility for the simultaneous measurement of total body Na, Cl, P, Ca, N and K. The effects of body size and shape have been incorporated into the calibration using a variable anthropomorphic phantom. The main interfering reactions are considered, and the method by which the results are corrected for these interferences described. The accuracy and precision of the technique have been determined. The procedure is suitable for measuring the critically ill since both irradiation and counting are performed with the patient lying supine. For a whole body dose equivalent of 0.5 mSv nitrogen was measured with a coefficient of variation (CV) of 2.2%; potassium was measured in the same counting period with a CV of 1.6%. Using a dose equivalent of 5 mSv sodium (2.2%), chlorine (1.6%) and phosphorus (2.9%) were also determined; for a 10 mSv dose equivalent calcium was measured with a CV of 3%.

Body Composition↗
PubMed1982

The feasibility of measuring total body carbon by counting neutron inelastic scatter gamma rays.

A technique is examined for measuring the mass of carbon of both ambulatory and non-ambulatory subjects. The method is based upon the detection of the 4.43 MeV gamma rays emitted from carbon nuclei when the body is irradiated with fast neutrons. The supine subject is irradiated laterally by a horizontal collimated beam of 14 MeV neutrons and the emitted gamma rays are counted by a shielded NaI(Tl) detector placed underneath the subject. The method has been calibrated for all sizes of subjects from 30 to 90 kg and there appears to be no significant interference from the other bulk elements of the body. Body carbon has been measured in six normal volunteers; body nitrogen was also determined by measuring the 13N induced in each subject in a second irradiation. Body fat was estimated from the measured carbon and nitrogen, and the values compared with those derived from skinfold thicknesses. The technique is proposed as a method of estimating long-term energy expenditure.

Ambulatory Care↗
PubMed1976

Counting losses in multidetector radiation counters.

We examined the reasons for the reduction in response of a multidetector radiation counting system when operated at high count-rates and established a convenient method of correction which is accurate to within +/- 1% up to 0-6 X 10(5) counts per second. In its application the method uses the observed count-rates from each detector at the time of measurement and previously determined values of critical time intervals of the electronic system. The detected signals establish these intervals in which further signals occurring within them are lost from the response. These further signals can also cause the loss of the signals establishing the intervals. The correction is of particular value when high-sensitivity whole-body counters are used to measure the activity of administered isotopes in metabolic studies.

Radiometry↗
PubMedDate not supplied

Risk factors for loss of lean body mass after liver transplantation.

BACKGROUND: After liver transplantation there is a fall in lean body mass. AIMS: To determine the risk factors for this fall in lean body mass using univariate and subgroup analyses. PATIENTS AND METHODS: Dual energy X-ray absorptiometry was performed in 36 patients (12 with Child-Pugh Class A, 20 with Class B and 4 with Class C disease) before and up to 24 months after liver transplantation. Univariate and sub-group comparative analyses were performed to assess possible risk factors for the fall in lean body mass post-transplantation. RESULTS: The pre-transplantation serum albumin inversely correlated with the fall lean body mass at 1 month (r = 0.55; p < 0.009) and at 6-9 months (r = 0.51; p < 0.05) post-transplantation. A positive correlation between the fall in lean body mass and: (i) cumulative dose of steroids administered at 2-5 months (r = 0.57; p < 0.05) and (ii) length of hospital stay after transplantation (r = 0.52; p < 0.05) were also observed. Neither the severity or presence of cholestatic liver disease pre-transplant, nor acute cellular rejection post-transplant were risk factors for a fall in lean mass. DISCUSSION: A hypercatabolic state post-transplant (represented by low albumin pre-transplantation), immobility, lack of exercise and steroid induced catabolism of muscle may cause the observed fall in lean mass after liver transplantation. Earlier transplantation of patients with better nutritional status and the use of low dose steroid immunosuppressive regimens may prevent the observed fall in lean body mass after transplantation.

Adult↗