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Biomedical subjects

P Tothill

Publications and source records attributed to P Tothill.

At least 91 records · Page 5Linked to original sources
PubMed1978

Bone blood flow and age in the rat.

1. The proportion of the cardiac output delivered to the skeleton and individual bones has been determined in rats of differing ages and weights with radioactive microspheres. 2. There was a decrease in the blood flow to the tibia--fibula, jaw, femur, pelvis, humerus, radius and ulna, and scapula with increase in age and weight of rats, but no change was seen in blood flow to the ribs, spine, skull or whole skeleton. 3. The proportion of the cardiac output delivered to the whole skeleton was approximately 3%. 4. The derived values for skeletal blood flow agree well with estimates by other authors using the technique of bone uptake and blood clearance of 45Ca.

Aging↗
PubMed1978

Post-mortem migration of bone-seeking radionuclides in the rat and rabbit and its effect on estimates of bone uptake.

1. The continued uptake of 18F, 85Sr and 47Ca by bone after death has been studied in rats and rabbits after aortic injection followed by quick killing, a period of recirculation of tracer before death, and perfusion of the carcase. In each case an approximately linear increase of bone radioactivity was observed during a period of 1 h at about the same rate. The proportionate increase depended on the initial concentration of bone-seeking nuclide, ranging from a factor of 1.5 to 4.5. Boiling the carcase did not increase the migration rate. 2. Delay between death and dissection may therefore lead to spuriously high bone concentrations of these radionuclides, leading to over-estimates of bone uptake, extraction ratio or bone blood flow.

Animals↗
PubMed1978

Techniques and errors in scintigraphic measurements of gastric emptying.

For the monitoring of gastric emptying, a gamma camera or scanner operating from one side of the patient is subject to variations of counting efficiency due to the changing depth of radioactivity. A double-headed scanner was used to investigate the effects of such changes. Tc-99m and In-113m were used as labels for the solid and liquid components of a meal. It was found that the depth of Tc-99m within the stomach decreased by a mean of 13 mm during the first half hour of emptying. Anterior detection alone underestimated emptying rates by an average of 26%. Death changes also introduced errors into "early emptying" measurements made unilaterally. Such artifacts of measurement may compromise mathematical analyses of emptying patterns.

Gastric Emptying↗
PubMed1977

The effect of dialysate calcium concentration on 1alpha-hydroxyvitamin D3 on skeletal calcium loss and hyperparathyroidism in haemodialysis patients.

The response of hyperparathyroidism and skeletal calcium loss in haemodialysis patients to treatment with 1alpha-hydroxyvitamin D3 and a dialysate calcium concentration of 1.375 mmol/l was compared with the response to treatment with a dialysate calcium concentration of 1.375 or 1.75 mmol/l alone over a 6 month period. In patients treated with 1alpha-hydroxyvitamin D3 there was a significant rise in plasma calcium associated with a significant fall in plasma alkaline phosphatase and plasma parathyroid hormone as well as resolution of sub-periosteal erosions. In these patients there was a significant rise in the calcium content of the forearm assessed by neutron activation analysis in comparison to patients treated with a dialysate calcium concentration of 1.75 or 1.375 mmol/l alone. In patients treated with a dialysate calcium concentration of 1.375 or 1.75 mmol/l alone there was no significant change in the plasma calcium, alkaline phosphatase or parathyroid hormone after 6 months and in these patients subperiosteal erosions either did not change or became worse. No significant difference in the response in these two groups was observed. This study indicates that treatment of haemodialysis patients with 1alpha-hydroxyvitamin D3 is significantly more effective than treatment with a dialysate calcium concentration of 1.375 or 1.75 mmol/l alone in preventing progression of hyperparathyroidism and skeletal calcium loss.

Adult↗
PubMed1977

Gastric emptying in diabetic autonomic neuropathy.

Gastric emptying was studied in 12 diabetic patients, six with and six without objective evidence of autonomic neuropathy and in 20 non-diabetic controls, using a double isotope scinti-scanning technique which differentiated between solid and liquid emptying. Three patients with autonomic neuropathy exhibited gastric stasis, although this was detected by conventional radiology in only one. Neither the patients with stasis nor those without exhibited abnormally rapid early gastric emptying. In patients without stasis, the normal differentiation between solid and liquid emptying was impaired, suggesting an abnormality of antral peristalsis not attributable to vagal denervation. Both intravenous and oral metoclopramide produced symptomatic improvement in two patients with gastric stasis and restored their gastric emptying to normal.

Adult↗
PubMed1976

Bone blood flow in the rat determined by the uptake of radioactive particles.

1. Two different suspensions of radioactive particles, 99Tcm-labelled microspheres and 59Fe-labelled resin particles, were injected into the rat central circulation in order to study the distribution of blood flow to the skeleton. 2. Measurements of particle uptake showed that the mean proportion of cardiac output flowing to the skeleton was 3-1%, a figure much lower than the valve of 27% found by Brookes (1970) in a similar experiment. 3. The blood flow per unit mass to individual bones covered a wide range.

Animals↗
PubMed1976

Gastric emptying rate measurement in man. A double isotope scanning technique for simultaneous study of liquid and solid components of a meal.

A sequential scintiscanning method was used to study gastric emptying in a total of 46 patients given a meal of cornflakes, sugar and milk containing radioactive markers of the solid and liquid components. In control and duodenal ulcer patients, liquid emptying was faster than solid emptying and could be represented as a monoexponential process, but solid emptying followed a different pattern, better represented as linear emptying with time. However, in patients who had undergone Billroth II gastrectomy there was no evidence of differential emptying of the two markers. In addition, rapid emptying of both markers occurred in the gastrectomy patients during the first 10 min after meal ingestion but did not occur in control or duodenal ulcer patients. The observations illustrate the limitations of using liquid meals to identify the effects of gastric surgery on emptying. Measurements of early emptying and of solid-liquid differentiation are necessary for full definition of gastric emptying after ingestion of a mixed solid and liquid meal.

Animals↗
PubMed1975

Inhibition of gastric emptying and drug absorption by narcotic analgesics.

The effect of intramuscular pethidine or diamorphine on gastric emptying and the absorption of orally administered paracetamol was assessed in eight normal subjects. 2 Both drugs produced a significant and striking delay in gastric emptying and absorption of paracetamol. 3 It seems inevitable that pethidine and diamorphine will retard the absorption of other orally administered drugs.

Acetaminophen↗
PubMed1975

Kidney depth measurements using a double isotope technique.

Differences in kidney depth, particularly between the two kidneys of an individual patient, may lead to distortions of the renogram owing to attenuation and geometrical factors. A method of assessing the magnitude of these variations was developed. A double isotope technique was used, employing 125-I and 131-I Hippuran, the kidney depth being a function of the ratio of the count-rates from the two isotopes. It was necessary to apply a correction for extrarenal activity, based on a third detector and doubly labelled human serum albumin. The average kidney depth observed was 7.3 cm; in only two cases out of 13 did the difference in depth of the two kidneys exceed 1 cm. It is concluded that when 131-I Hippuran is used the consequent distortion of the renogram is acceptable. With 125-I the distortion may be excessive, even though the contribution of extrarenal activity is then reduced. There was frequently an apparent increase in the depth of activity during the renogram attributable to intrarenal translocation of the tracer.

Anthropometry↗
PubMed1975

The fate of four 75Se-labeled amino acids: studies of some unsuccessful pancreas-scanning agents.

The Radiochemical Centre developed a number of alpha-amino acids labeled with 75Se in the hope of finding a pancreas-scanning agent superior to L-selenomethionine. Six were submitted for clinical trial and we tested four of these: D-selenomethionine and three derivatives of selenocysteine. Dynamic scintillation camera studies showed that liver uptake was substantial in all cases but that the time course of accumulation and removal differed between agents. Plasma radioactivity curves demonstrated differences in initial removal rates. Two of the agents showed evidence of incorporation of activity into protein and release into the circulation just as with L-selenomethionine. Whole-body counter measurements showed that the retention of activity from the agents exhibiting early plasma protein incorporation was similar to that of L-selenomethionine. Much of the activity from the other two agents was excreted faster but small proportion was retained for a long time. Although the cummulated activity and absorbed dose were substantially less for at least two of the agents than for 75Se-L-selenomethionine, the lack of sufficient pancreatic concentration renders them inferior as scanning agents.

Amino Acids↗